While driving my mk2 VR6 converted Golf the engine went dead and refused to start again. The fuel pump doesn't prime. I have tested the most likely things in this order 1. fuel pump and fuel pump wiring harness, by jumping the relay. Pump ran fine. 2. Replaced fuel pump relay with a known good one from funkbaron's car, still nothing. 3. Tested ECU perm live, spot on. 4. Checked ECU relay function, again, fine. 5. Checked ECU earths, all fine again. 6. Swapped ECU for working one from funkbaron's car, still nothing.... Does anybody have any more suggestions, as I think me and baz have exhausted all the options. The car had a fault code read for a faulty maf sensor. I borrowed the one from baz's car and it ran fine, but cut out 10mins later, i'm not sure if the two could be related. Also, i'm unable to read fault codes from the ecu now, which leads me to think wiring to the ecu is faulty, but we have done all the tests. HELP![:^(]
Should add, we also swapped the fusebox over, and checked continuity of all the fuel pump and ecu power supply wires, from the fusebox back....stumped
Working fine as the ecu relay clicks when the ignition is turned, i jumped the relevant pins on the ecu plug and tested for 12v from the relay, tested OK. I'm definitly erring towards an ecu wiring issue, as it won't give out a diagnostic code, we just get the "error" message, as if it has no power. Yet, we've tested the perm live and the relay live to it, both check out fine...
does the vr have an isv, and if so does it buzz? (not suggesting its the problem, but if it does buzz then it suggests the ecu is 'alive') Any alarms installed in the car?
check pin 2 of the fuel pump relay socket (or whatever corresponds to pin 86 of the relay) does it go live with the ignition? Also check pin 3/leg 85 of the fuel relay socket, this is the feed from the ECU (comes from pin 9 of the ecu, runs to G1/3 at the back of the fusebox, yel/blu wire I think, I'm looking at US wring diagrams here)
VR6's have an ISV, but it isn't like the mk2 8v job, it only runs when the engine is idling. The yel/blu wire I've tested for continuity to the relay pin, which tested fine. I've ran a test to the fuel pump relay to see if it gets it's ground signal from the ecu for the fuel pump priming, which it didn't, so the problem is still tracing back to an ecu issue. Thanks for the suggestions.
looks like a dead ecu as you say then, could it be the age old 'poor gearbox earth -> dead ECU' problem?
The only issue with that is that we have tried Baz's ECU and still no joy. We have also checked all of the live's and grounds on the ecu wiring pins and they seem fine. Going to have to untape it all this weekend and hopefully find something! cheers for all the suggestions though guys, keep em comming
The diagnostic wiring is fine, I ran continuity checks on it when we first wired the car, it's only the two wires to the ecu for the white plug and the +/- to the black one, and we've since used it to read fault codes. Car has ran fine for the last two months, and only died 10mins after fitting my MAF to it. To reiterate, the ECU earths are all fine, the ECU power supply relay and wiring is fine, we've tried swapping all relevant relays and fuses, even swapped the fusebox....there's not much else to do now but unwrap all the wiring and start again
Yes, but its NOT fine now is it If the car has an immobilisor the diagnostic wires are tied into that, which is why I suggested you check it agian
Does not work like that mate. Immobiliser circuit and K lines are two serparate enities. If the immobilier is active and you by attempt to start the car without transponder the car will start and cut out in 5secs. This is something else no doubt as they are not getting and data off the DLC K line. Furthermore older cars did not come with an immobiliser circuit.
If you arent able to connect to the ECU via the diagnostics, then the ECU is not being powered up at this point. You mention that it is getting switched live with the ignition switch, have you tested the perm live?
Really I had the impression the immobilisor wire ran from the ECU to the transponder unit, then from there to the diagnostic plug, I'll have another look at J_S's motor on Saturday.
Most definitely not - the diagnostic wires dont have to be wired in for the car to start and run when the ecu has a factory immobilisor In a MK3, the diagnostic wiring is part of the dash loom
Ok cool, I really need a UK ABF wiring diagram with transponder, all the ones I have are US and dont explain how the transponder is wired in, or are pre-96.
I should clarify, this is an OBD1 engine, sorry for any confusion, there is no immobilisor/transponder. Yep, pin 54 perm live reads 12v. We know it's deffo ECU power related, but all the earths and lives to the ECU check out perfectly, this is why we've hit a brick wall. I'm popping over to look at the car again tomorrow, so will take a fresh look at it, thanks for the suggestions.
