Honda CX500 & GL500 Forum

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02-25-2010, 8:12 AM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off Reading your past posting I think I found a problem. You state you have 12 volts at the red/white wire at the tip over switch? The correct reading on R/W should 0 to 1 volt. It is the ground path for the main relay coil, all voltage should have dropped at the coil relay. Key on Tip switch wires: BL/G 12v R/W 0 v or close to 0 G 0 V or close to 0 Grounding the R/W should close the main relay contacts CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

02-25-2010, 9:51 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Thanks for that ... ok I just went and checked again... I wrote incorrectly... At the Tip Switch wires I do have 12 V on the BLACK wire and just about 1V on the RED/WHITE wire. ON the MAIN RELAY  Key OFF I have 12V between the RED and the( BLACK, BLACK RED ) Key ON   zero voltage here....relay is working.   Key off ZERO VOLTAGE between RED w/WHITE STRIPE and BLACK w/WHITE STRIPE..... Key ON 12 Volts between RED W WHITE STRIPE AND BLACK W WHITE STRIPE. So that all seems appropriate ....... I see that the circuit is completed to the  AIR VALVE via the BROWN WIRE leading from the FUEL PUMP RELAY.... I can trace the power to the air valve  but I cannot seem to get any power coming out of it on its way to ground.... Do you think I could be on to something there?? As always .... thanks for your interest in trying to help me out... I know I am close to getting this machine running properly...    Report

02-25-2010, 10:19 AM wildmanwill Joined on 05-25-2008 Chester County, Pennsylvania Posts 4,034 Re: cx 500t engine runs 3 seconds then shuts off For some reason I thought you had sold your turbo.  Guess you still have it.  This is the bike that sat for 18 years, right? 1983 CX650 Turbo 1982 CX500 Custom Donating Member    Report

02-25-2010, 10:21 AM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off ? Volt meter neg lead connected to ground(ground wire to chassis/battery ground) KEY on everything connected: Main relay W/R wire voltage measured to ground? Fuel relay BL/BR wire voltage measure to ground? Brown wire at air valve measure volts to ground? Brown wire at fuel pump measure to ground? Black or green wire at fuel pump measure voltage to ground? CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

02-25-2010, 10:56 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Nope ...still have it ... trying to chase down an electrical gremlin.... D    Report

02-25-2010, 11:11 AM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off What are the voltage readings asked for in the above post? KEY on everything connected: Main relay W/R wire voltage measured to ground? Fuel relay BL/BR wire voltage measure to ground? Brown wire at air valve measure volts to ground? Brown wire at fuel pump measure to ground? Black or green wire at fuel pump measure voltage to ground? CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

02-25-2010, 12:25 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Main Relay I get 12 volts constant Fuel Relay I get 12 volts for 3 seconds Brown wire at Air Valve 12 volts 3 seconds Brown wire at fuel pump 12volts 3 seconds Green wire at fuel pump 12 volts 3 seconds    Report

02-25-2010, 1:26 PM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off OK If you have a constant 12 volts at the W/R, the tip over switch is not grounding the relay and if you have 12 volts constant at the Black wire on the tip over switch then: I would try to ground the W/R wire at the tip over switch. That should close the main relay and supply a constant 12 volts to the brown wire at the fuel pump and air valve. Then the tip switch or wiring to the tip switch is faulty. CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

02-25-2010, 1:37 PM CXTURBOBOOST Joined on 05-02-2007 Lincoln, NE Posts 440 Re: cx 500t engine runs 3 seconds then shuts off Okay... Looking at the schematic... All of what Showkey said is true...  Dan told me he checked the tip over switch, but the wiring from the tip over could be the problem...  Recheck and check the wiring to make sure good continuity with low resistance so that we know that all is well. Is the red wire on the main relay a constant 12V? If not we have a problem...Is the clock working?  I just want to know if the other side of the relay is working... PK    Report

02-25-2010, 3:32 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hey Pete... Tip over red wire w white stripe has 1volt..... 12 volts on black... Red wire on Main relay is always constant 12 volts... The clock is working perfectly... Other side of the relay seems to work fine... Dan    Report

02-25-2010, 6:13 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off What happens if you jumper the switched side of the main relay? CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

02-25-2010, 6:55 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello All..... just because i checked the Tip Over Switch.(Automatic Fuel Shut Off)   .. and I was able to obtain the readings in the service manual R/W to G  less than one Volt.... BL to G was 10volts.  All with ignition switch on.....I suppose doesn't make it good.   I didn't do the Off Frame test....has anyone ever had a Tip Over Sensor go bad that you guys know of? Dan    Report

02-25-2010, 7:01 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off I am thinking the AIR VALVE may have something to do with my problems... Does anybody know how to check it?  I don't see where the service manual gets into the Air Valve but it looks like that grounds the brown wire coming off the fuel pump relay?  Any ideas?    Report

02-25-2010, 7:12 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off Air valve is just wired in parallel with the fuel pump. Should not have anything to do with the fuel pump. Look at page 23-10. Notice the switched side of the main relay. If you jumper that out and the bike stays running odds are pretty good you'll have it narrowed down to the tip over switch. Failure isn't common but I have read about it happening. I think someone opened one a few years back to see what makes it work. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

02-25-2010, 7:28 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello Showkey..... ok here is what I did and it seemed to have no affect... I took your advise and grounded the R/W wire at the TIP OVER SWITCH and still problem persists.  Main Relay is working but Fuel Pump relay gets a three second shot of power then it goes dead until I turn the key off and back on again.  I can also do the same thing with the kill switch to get the Fuel Pump powered for 3 seconds before it cuts off... hummmmm I can jury rig the Fuel Pump relay and send constant power to the Fuel Pump with a paper clip between the black brown and brown wires and make the pump run constantly but that fries the relay for some reason and besides that it is not solving my problem... But then the engine does run.   Is this making any sense??    Report

02-25-2010, 7:46 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off If you went between black/brown and brown, you powered the full current load of the fuel pump and air valve through the ECU. Hopefully you didn't kill it. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

02-25-2010, 8:29 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off No ... it didn't hurt a thing and I sent the ECU off to Pete to test it and it ran just as it should... But I don't want to experiment any more with the fuel relay... thats for sure.. I just want to get it working... I am surprised no one has seen this one before.  D    Report

02-25-2010, 8:47 PM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off You should have jumped between the red and brown wires the I hope the bike would run? This would by-pass the pump relay. Jumping between BL/BR and brown does not make sense and would not suspect the bike would run?????But it did Unplug the fuel pump relay and measure the voltage available to ground on each wire. Red would be 12 v? Black would be 12 v? Brown would be 0 v Black/brown 0v ? Answer the above question before doing the next step! Maybe you've done this already? With every thing connected: What happens if you ground the bl/br wire at the fuel pump relay? I would suspect the main relay closes and the bike runs? If it does run then the ECU is not closing the fuel pump relay and since you have tried KNOWN GOOD ECU then we are slowing getting back to the ECU inputs are not satisfied???? CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

02-25-2010, 8:51 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello Don... I will give the sensors a look tomorrow and see what I turn up... That is a fascinating bit of troubleshooting... I get no fault codes or illuminated LEDS ....    Report

02-26-2010, 9:29 AM Abes_CW Joined on 04-17-2007 saskatoon Posts 3,036 Re: cx 500t engine runs 3 seconds then shuts off fascinating thread. 1983 GL650i Had 4 CX/GL's at one point this year, down to one, next spring is another adventure! age 38 (29 plus tax)    Report

02-26-2010, 12:27 PM CXTURBOBOOST Joined on 05-02-2007 Lincoln, NE Posts 440 Re: cx 500t engine runs 3 seconds then shuts off The only sensing on the bike would be from the kill switch, and the tip-over switch... PK    Report

02-26-2010, 1:36 PM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off Do we know exacting when (parameters) the ECU grounds the BL/BR wire closing the fuel pump relay? The ECU is grounded by the green wire has that connection been checked theory being if the ECU is not grounded the BL/BR will never be grounded???? Don mentioned prior the bike came (purchased) with this problem so after all this.....are we looking for a misplaced wire in a connector by the prior owner????? If that's the case known good bike park next the the "broken" bike a do connector by connector comparison. By misplaced I would include a wire placed in the wrong connector cavity, loose pin fit, corrosion etc. CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

02-26-2010, 2:33 PM CXTURBOBOOST Joined on 05-02-2007 Lincoln, NE Posts 440 Re: cx 500t engine runs 3 seconds then shuts off Assume nothing, check everything... As always...(Unless you bought it new) PK    Report

02-27-2010, 1:40 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off ECU ground wire has been checked... if i disconnect the ground nothing works... as it is everything works on the electrical system except the fuel pump cycling off when it should be running... I loose power at the fuel relay after a short 3 seconds.     Report

02-27-2010, 1:48 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Here are a few more readings.... at the connectors coming from the ECU   with ignition switch ON POSITION Green connector rw wire 5v light blue 5v green 0 v Blue connector rw 5v wh 5v gr 0v Red connector pink 0v bl 0v green 0v Clear plastic connector red 5v orange 1v green 0v   plus i hear a small click noise then i perform the check Yellow connector red 5v orange 5v green 0v Black 4p connector rb  12v y 0v rw 0v bw 0v Red 2p connector r 12v b 0v    Report

02-28-2010, 6:04 AM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off You should have jumped between the red and brown wires the I hope the bike would run? This would by-pass the pump relay...... Does the bike run? What happens if you ground the bl/br wire at the fuel pump relay? CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

02-28-2010, 7:37 AM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off  showkey wrote: You should have jumped between the red and brown wires the I hope the bike would run? This would by-pass the pump relay. Jumping between BL/BR and brown does not make sense and would not suspect the bike would run?????But it did Unplug the fuel pump relay and measure the voltage available to ground on each wire. Red would be 12 v? Black would be 12 v? Brown would be 0 v Black/brown 0v ? Answer the above question before doing the next step! Maybe you've done this already? With every thing connected: What happens if you ground the bl/br wire at the fuel pump relay? I would suspect the main relay closes and the bike runs? If it does run then the ECU is not closing the fuel pump relay and since you have tried KNOWN GOOD ECU then we are slowing getting back to the ECU inputs are not satisfied???? Ok, I'm looking at the schematic here and this is my theory so please correct me if I'm wrong. The black wire from the ECU supplies 12 volts to the fuel pump coil for 3 seconds at ignition on. That same black wire also feeds 12 volts to the SWITCHED side of the main relay which branches off and feeds each injector.  Now the other side of main relay switch is a constant 12 volts from red.  If that SWITCHED side of the main relay is OPEN you get your 3 second 12 volt feed from the ECU to the fuel pump and injectors and that's it?  Correct?  Now once the main relay switch closes, your 12 volts from the red wire feeds back to the black wire which of course feeds 12 volts to the fuel pump relay,  injectors and ECU.  The ECU may or may not even care if it sees 12 volts on that black wire from another source besides itself.  In other words the ECU isn't responsible for supplying 12 volts to the fuel pump relay AFTER the bike is started? The black/brown from the ECU is ground. Now, if the SWITCHED side of the MAIN RELAY isn't closing the fuel pump will not run?  If the switched side of the main relay is jumped out (red and black) and the bike does run, that would go back to the tip over circuit keeping the main relay open? CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

02-28-2010, 7:49 AM CXTURBOBOOST Joined on 05-02-2007 Lincoln, NE Posts 440 Re: cx 500t engine runs 3 seconds then shuts off But is it just the tip over switch, or is it also controlled by the shut off switch? I've thought it was the tip over switch from the start. I offered to send him one of mine...It could also be that the wire going to or from are bad... I suggested making sure good continuity existed. I've done all I can do from over a phone... PK    Report

02-28-2010, 8:12 AM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off If the kill switch failed he shouldn't get the 3 second fuel pump feed.  Although if it has more than one set of contacts that could be a possibility, and we know how flaky those switches are on the 500T. Definitely could be the wiring too but I would hope the first thing he did was a simple continuity check on each wire. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

02-28-2010, 9:33 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off THANK YOU Showkey and George...... ok I am getting a little bewildered but just stay with me and I should have the bike running in no time... Showkey wrote to jump between the red and brown wires at the fuel pump relay and that is what I did previously (but misspoke on the color wires sorry)  and the bike runs.... (no three second stopping) and so does the fuelpump wheather the ignition switch is on or not.  Has the same effect as plugging a 12v power supply directly to the fuel pump. If I unplug the fuel pump relay with the ignition switch ON and measure the red to ground I get  12 volts.. if I measure the black to ground 12 volts.  So far so good  By grounding the bl /br wire.. it is as you said...... the fuel pump runs!  I think you  are on to something.   So then the ECU is not closing the fuel pump relay.  That leaves us to "slowing getting baack to the ECU imputs not getting  satisfied"  So maybe the tip over switch is checking good but not good.... Anyone want to sell me a known good tip over switch?  See if that does the trick?  Dan    Report

02-28-2010, 9:41 AM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off I think we are on the same page? Since the bike does run with the pump "hot wired". I don't see answer to your question, What happens with the main relay jumped (RED to BLACK)? Same with my question what happens with the fuel relay wires jumped RED to BROWN? My thinking is the BL/BR wire is the ground to close the fuel relay relay and the power to the fuel relay coil is the black wire from the main relay. I was thinking the BL/BR is ground for 3 seconds on start and the black and BL/R wire has 12 volts any time the main relay is closed. The ECU can turn the pump off when it see's a fault example of this open or short in an injector the fail safe is the pump is turned off. So I was thinking the ECU controls ground for the pump relay on the Black/brown wire??? Appears we were typing at the same time QUESTIONS NOW ANSWERED:) The tip switch appears to OK if the bike runs with the Black/brown grounded CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

02-28-2010, 9:45 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello Pete....as always thank you for your help...  about that tip over switch you mentioned.... let me know what you need to get for it and see if that is what fixes this thing....I hope you have been right all along... that would not surprise me.. Dan    Report

02-28-2010, 9:51 AM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off Does the bike run good and no codes with the BLACK/BROWN wire grounded? I asked because for some codes to set the engine has to be engine running, if either injector is open or shorted the pump would stop. CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

02-28-2010, 10:06 AM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off Ok after looking at the schematic again my last theory can't be right. I was assuming the black wire off the ECU also supplied 12 volts but that can't be since that black wire also runs up to the fan and thermo switch and running that off anything but a relay would make no sense. Instead the main relay should close and and send 12 volts to the fuel pump relay, fan, injectors and the ECU. If r/w was cut from the tip over sensor, would the main relay energize at all? Could it be the ECU needs to see the 12 volts on that black wire from the closed main relay and that wire is open? The 3 second start cycle could just be a different part of the program when it sees power cycled at Y? CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-01-2010, 1:35 AM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off Glider, There have been known cases of tip-over switch failure. I have seen and ridden one CX500Turbo here in Oz that has had the airvalve system completely removed, and the connector just taped-up (plus plugging the relevant hoses). It starts easily - in the 10C to 40C range of temperatures - so just disconnecting that plug should verify whether that unit is affecting your bike - I doubt it. Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

03-01-2010, 1:40 AM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off I hope you have all noticed a fundamental mistake in the circuit diagram - there is one wire junction shown as a joint - it should be a "fly-over" i.e. NO joint. Right near the relays. Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

03-01-2010, 1:43 AM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off The tip-over switch is a form of latching relay - if it ever operates, it remains operated until you turn the ignition switch OFF, then on again with the switch in the normal "bike-upright" position. Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

03-01-2010, 5:05 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hey Don et al..... Pete is going to graciously send me a tip over sensor and give that a try and in the meantime I am going to go back through the troubled machine from the beginning to see what it is that I may have overlooked... I think I mentioned that jumping the fuel relay with a paper clip makes the fuel pump and engine run but it also frys the relay after a while.  Honda engineers didn't send along paperclips with the bike either!  I am enjoying this troubleshooting journey but I would rather it be with the wind in my face rather than on a shop stool with a multimeter in my lap. Most importantly I want to thank EVERYONE on this forum for chipping in and wanting to help me... Dan aka Gliderbuff    Report

03-01-2010, 6:06 AM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off Don, Where is this error? I've never had any problems in that area so I've not compared the original wiring to the schematic. I had my doubts about something so I checked the 650T schematic which is identical too. That could be a source of confusion here. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-01-2010, 7:47 AM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off Gliderbuff/George There is a difference in the circuit I am using - it's 0030Z-MC7-6000, whilst you report 0030Z-MC7-6700. George, number ONE error on our circuit is that - just above the fuel pump relay, on the left hand side of that symbol - there is a DOT on the crossing where the BLACK wire crosses the RED wire. This should NOT be a connection - it should be a jump-over. There are actually TWO faults in our circuit. The second is that there is a wire shown from the left hand Bl/R pin of the right-hand Injector symbol, going upwards and across to join with the Bl wire coming up from the main relay symbol. This is, of course WRONG, and the connection does NOT exist at all. So, are we being led astray by some other wiring diagram fault? From the sequence number of the drawings, it just might be that the 6000 drawing was the first ever drawing to be published, and the 6700 drawing was a SUBSEQUENT issue, with corrections made. If we had access to a list of corrections to the manuals, these two errors might show as entries on that list, if your drawigns have neither faults Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

03-01-2010, 8:03 AM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off Gliderbuff, I have documented the sensor readings of 6 CX500Turbos that have needed fault finding, and there is one GLARING error between your measurements, and what I have measured on ALL of these six bikes. Your measurements tabulation in your posting of "Yesterday 4.48AM" on this thread shows ALL of the three wires to the RED sensor (the P ign sensor) as being zero, with the Ignition switch in the ON position (and I assume it is with a battery connected to teh bike). This is WRONG. One of the leads to the RED connector is the all-time supply to that sensor (whilst the ignition switch is ON), and it should show a slightly lesser voltage than the full battery supply volts - about 0.6 to 0.8 volts less. If your tabulation is correct, then you have a broken wire between the P ign sensor and the nominal 12 volt supply to that sensor. It's nearly 3am local time here, and I will stick at identifying which wire carries that voltage and current to the P ign sensor until I find which one. Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

03-01-2010, 8:29 AM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off From the P ign sensor, the G/W wire is one information voltage fed to the Boost meter and the ignition module, and, together with the voltage on the Pink wire, is the analogue output from the P ign sensor that is interpreted as the amount of boost pressure that is being fed to the injectors and the inlet tract to the cylinder input ducts. It is the voltage difference between these two wires that is sensed, and this produces the "advance back-off" in the ignition timing which is needed to stop the motor from pre-combusting when on boost. It should be the Bl/W wire from the P ign sensor that has the "slightly less than battery 12 volts" on it - this wire is traceable back to the Bl/W feed - to or from - the MAIN power relay and goes also to the ignition module, the power to the ignition coils, and what is called the "Starter, Engine Stop, Lighting Switch" on our model of the Turbo - this where your wiring diagram WILL BE different from mine - as you don't have the lighting switch function. BUT, the main thing is that you obviously have the 12 volt supply to your ignition module (spark unit) and your ignition coils - to enable your motor to run at all. Therefore the fault must be in the small portion of the loom that takes this 12 volts to the P ign sensor, or it may be a faulty termination of the wire INSIDE the connector (sealed with clear epoxy in our connectors), or an actual fault inside the P ign sensor - not the first time that a P ign sensor has been found faulty. BUT, I'm guessing that you haven't measured that voltage on the Bl/W wire by piercing the insulation of that wire right where the wire disappears into the P ign sensor body. So, the most likely fault is a broken wire in the loom, or a bad termination of the wire onto the plug/socket's pin right inside the RED loom's connector. Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

03-01-2010, 8:42 AM CXTURBOBOOST Joined on 05-02-2007 Lincoln, NE Posts 440 Re: cx 500t engine runs 3 seconds then shuts off Don, Then why does the bike run correctly when 12v is applied to the fuel pump with no errors given by the ECU? If the Fuel system light goes off and stays off with the bike running something seems odd? PK    Report

03-01-2010, 9:24 AM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off Pete, The P ign sensor and the boost meter are not needed to let the bike run at idle - they are only precationary measures for when on boost. The 12 volts is obviously there on the Bl wire for some of its recipients, but, according to the measurements table, it is NOT on the P ign sensor. I can only go by what the guy measures at the other end, and what logic dictates from the circuit. None of us has the design brief for the ECU - if we did have it, there would be much easier ways of diagnosing our bike's faults. I wouldn't say "the bike is running" properly - up to three seconds is hardly a correct test of the fault-reporting LED system. Do we know how quickly those LED faults are "reported" to them? Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

03-01-2010, 9:38 AM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off There will be a certain "time constant" built into the computer in the Spark Module when it senses the P ign voltage. This will be fairly short when the bike is running in boost, otherwise it would take too long to sense over-boost and the motor would destroy itself before the information was processed. HOWEVER, that time-constant network is starting from scratch when the motor is starting up, and it would be reasonable to assume that a 5 second or longer overall time constant would be applied to this analogue sensing input. So, the Spark Module could be saying to the fuel pump "there isn't a Pign sensor connected, so I'm not going to start you". The LEDs don't have a fault readout for "no Pign connected" nor any other P ign fault either, do they? That's all driven by the ECU's computer. Unfortunately for my theory, there appears to be no way that the Spark Unit "talks to" the ECU - except that there is the commonality of where they both sense boost pressure - but the above may help. You will notice - in Chapter 24 (page 17 in my manual) where the calibration of the P2 and P ign sensors is identical, so they tell identical "stories" to their respective computers. Let's find out what Gliderbuff says about those three "all zero" voltages at the RED connector. Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

03-01-2010, 10:18 AM CXTURBOBOOST Joined on 05-02-2007 Lincoln, NE Posts 440 Re: cx 500t engine runs 3 seconds then shuts off Don, I understand what you are saying.. That wasn't my question. My understanding is that he is able to ride the bike just fine with no error codes when the FP is given 12v... That's where I'm confused by your theory. PK    Report

03-01-2010, 1:03 PM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off I thought Glider already confirmed when the Black/brown is grounded at the fuel pump relay the bikes runs? So the ECU is not grounding the relay coil???? Now why is the next problem? PS. I was using 0030-MC7-6700 diagram CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

03-01-2010, 7:05 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello Don in Oz.... ok there are two red connectors right?  The one red one is a  round 3p connector (looks just like the blue, yellow, clear, green ones)  The readings are zero zero zero volts ... pink wire 0v, green/wh 0v, and bl/wh 0volts...... now the other red connector is rectangular in shape and it does have 12v running on the red wire and 0 volts on the black wire. So from what you say then this is the WRONG reading at the P ing sensor and possibly my problem??   Dan    Report

03-01-2010, 7:17 PM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off Gliderbuff, You are getting VERY close to the problem, for sure. The round red connector is the one that connects the P ign sensor to the "rest of the world" and it MUST get about 11 volts there on the Bl/W wire for the sensor to work. Use your voltmeter/multimeter with a dress-making pin (to pierce the insulation) attached to the positive probe, start at the red connector and work your way back down the loom until you find the volts - with your ignition switch ON. Good hunting, mate. Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

03-01-2010, 7:52 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off OOPS..... Oz.. I was taking my readings off the female end of the connector unlike the others the male end supplies the current at the red connector and now I DO get the power you talk about.  pink is appox 9V,  green/wh 12V and bl/wh is 12V.... thats to the P ing sensor.   I should have figured that one out... Dan    Report

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