VR not starting! - Crank sensor not getting power!

[Niges16V 0]

I'm in need of help again! Had the VR towed home by the AA after it refused to start on Friday.

 

The AA reported that there is no spark or fuel and suspected the alarm as it was triggered prior to the non-start by the window being open. He wanted to check the crank sensor but run out of time.

 

I doubted the alarm theory as it is a 18month old Autowatch 160RLi which is known to be reliable, but when I couldn't connect VAG-COM due to "Excessive comms errors" I thought maybe the alarm was cutting power to the ECU. I called the installers today and they couldn't see the link as they cut into the fuel and starter motor (the starter motor kicks in as normal). They said they could bypass it to rule it out but at a fee of £50.

 

The other 'usual suspects' I believe are the 109 relay and ignition switch, but both were replaced last year. I hope to get a scope to check the crank sensor tomorrow.

 

Does anyone know what to do with the scope to check the crank sensor? Any other suggestions greatly appreciated!

[Critical_Mass 10]

Hello mate,

 

Before you try anything else change the ignition switch. Mine refused to start, although it was turning over but not attempting to fire up. Had RAC round, they said Crank position sensor- changed, no joy. Had them round again, they said it was the immobiliser- though i didnt check this as it was easier to try other things first. Ive learnt not to necessarily take what the recovery bloke says as being the case- i even said to the bloke after asking on the forum, if it could be the ignition switch and he said "no definately not" (BULLSH!T). I changed the ignition switch and viola fired up first time.

 

viewtopic.php?f=1&t=56335&hilit=ignition+switch

 

Failing the ign switch, which i doubt, ive got a crankshaft position sensor you can try- the old one, which does work.

[Niges16V 0]

I did actually change the ignition switch last year along with the 109 relay when I had the same problem but intermittant. It was from GSF so it could be possible that it has failed again. I will try to test it tonight by removing the wire connector block and shorting out the pins to create some nice sparks which should start the engine - according to what I see on the telly :D

 

Thanks for the offer of the sensor, I may well take you up on that after i've checked it out with a scope.

 

I'm going to cancel the alarm bypass as it is £50 and doesn't sound as though it is the problem. If I can't figure it out in the next couple of days I think I had better tow it to a garage.

[mattkh 0]

Hi

Ya rule out the ignition switch first

[Critical_Mass 10]

Yeah, mine is one from GSF too, they are prone to failure. Best get a VAG one ideally. I just wanted to get it fixed quick without having to order the part.

 

Let us know about sensor mate.

 

Gaz

[Yandards 0]

Humn, I would also check out the ignition switch, GSF ones are really bad.

 

Do you have any extras aside from the car key and a fob on the keyring? If you do then this tends to put excessive load onto the ignition switch hence the failures.

[Niges16V 0]

Nope, no extras, just a key & fob as the jingle jangles wind me up. I've even stuck fluffy stuff on the steering cowl to stop the fob clonking it while driving along :D

 

Anyone know how to test the switch, or should I just try to 'hot wire' the car with the switch removed??

[Niges16V 0]

Booo. Checked the ignition switch & crank sensor last night and they seem fine. Gave in and called a mobile mechanic out this morning who basically double checked what |had and came to the conclusion that it was the alarm.

Called out the alarm chaps who promptly bypassed the system and still no joy.

So I'm £85 down and got nowhere!

 

Any suggestions? or should | hire a trailer and tow it to a Rado specialist as I have no confidence in Joe Bloggs mechanics.

[Niges16V 0]

I had previously tested the resistance across pins 1&2 at 565 ohms so assumed the crank sensor to be OK, but to be sure I borrowed a scope and got these results:

 

Pin 1 Red - 3.58V @ 10Hz ac wave!

Pin 2 Green - nowt, just a bit of noise

Pin 3 Black - as above

 

So I guess the problem lies deeper within as there is no 12Vdc getting to the sensor. Can anyone shed some light on this or at least provide a wiring diagram??

Getting a bit tired of this now :(

[dr_mat 0]

Can you swap the ECU? Can you still not talk to it with VAGCOM? What about jumping the relay 109 socket with a bit of wire, make sure there's 12V at the ecu and then see if you can talk to it?

The ECU is responsible for providing power to the sensors, so it makes sense to start looking there.

[Niges16V 0]

No, don't have a spare ECU

VAG-COM just comes up with "too many comms errors", it did find the ABS details at one point but then just reported "too many errors" again. The mobile chappy didn't have any luck with his "£8000" diagnostic kit either.

If I take the cover off the 109 relay and close the contact manually, will this work? I could then try VAG-COM again. But too be honest, I'm going beyond my limited knowledge at this point and therefore wouldn't know what is good or bad. I've booked a car trailer for the morning and will take it to JMR in Littlehampton.

 

If it is the ECU, is it a case of simply getting another from a breakers and bolting it on?? I doubt it!

 

Oh, forgot to say that I have found the wiring diagram on the Russian site and concluded that the crank sensor is OK (maybe).

[Kevin Bacon 5]

If you do replace the ECU, yours will be the CP variety being a 95 car, and they're pretty hard to get hold of now.

 

Has VAG-COM ever been able to connect?

 

The ECU relay just provides power, it won't affect the K line comms behaviour.

 

Not seen "too many errors" before, but it could be laptop related, or the little thin grey wire coming out of the brown termination block behind the centre console is somehow damaged. That's your comms line to the engine and ABS ECUs. I would guess it's the laptop being as both are uncontactable. Are you using an old laptop with comm port or a USB cable? If comm port, try reducing the FIFO buffers to the slowest setting (Device manager, comm ports, Advanced settings).

 

Or, the worst case scenario, the ECU has internal problems.

 

I guess the simplest solution would be too find someone with a 95 VR and swap bits over until the cause is found.

 

Replacing the ECU is 5 minute job. Lift the generously sized scuttle cover, LOL, and observe the Master of engine control that lives within. You'll see the ECU plug has a slider on it. Pull it toward you and that will unlatch the plug, pull it free and put to one side. Get a 10mm spanner, undo the single bracket retainer nut, then from the leaf guard side of the guard, pull the ECU toward you to unhook it from the car and out to freedom.

 

Whilst the ECU plug is off, make sure it has a nice orange water seal inside it and that none of the pins are corroded.

 

Do the same on the twist lock connector behind the aux water pump. The crank and TPS pins are gold plated, the rest are plain, so don't confuse the gold with burnt discolouration ;-)

 

Good luck. I'm sure Mr Mitchell can sort it.

[Niges16V 0]

Thanks for the detailed responce Kev, most helpful as always!

 

Yes I have been able to use VAG-COM in the past with my ebay opto cable with USB converter, and it also works on the wifes Golf III. The error I got was : Address 03

Controller:

Note: Excessive Comm Errors

 

So you could be right about the comms wire, but just a bit coincidental that it breaks and I have this breakdown. I've spent a week trying to figure it out and it's just getting more complicated. The only thing I could try now is a ECU swap as you explained, but as I do not have access to another and the weather is not ideal for outdoor mechanics I am going to have to rely on Mr Mitchels expertise.

[dr_mat 0]

There's a few Golf VR6 ECUs on ebay, http://search.ebay.co.uk/vr6-ecu ..

 

Not sure if they'd work with the Corrado VR6 wiring loom though. At least you have a late VR, so it's got all the right sensors and a coil pack.

[Niges16V 0]

I think that most the Golf's are OBD2. Didn't our old friend Trig have probs with his ECU (same year as mine I think) and ended up converting to OBD2 at great expense?

Just starting to worry that it may be an expensive fix which will open the debate as to whether it is worth it! I'm on 155k with no evidence that the chains have been done, add these 2 factors together and it's probably mega bucks! Maybe a 24V conversion??? or am I jumping ahead of myself a bit??? :lol:

[Kevin Bacon 5]

I know all about the car being off the road with complicated problems :lol:

 

As it happened all of a sudden and VAG-COM worked previously aswell, it's certainly pointing to the ECU, assuming everything else is OK....fuel pump / pump relay, for example.

 

I can't remember if it's only crank activity triggers the pump or not, but when you flick the ignition on, do you get pump activity for 5 seconds? That would outrule the pump and it's relay.

 

Oh well, good luck!

 

An R32 with a DTA would be a nice conversion 8) At least if standalone ECUs break, you can send them away for repair, usually costing £50, rather than scouring the country for an ancient VW box!

[dr_mat 0]

I thought the full OBD2 conversion only cost a few hundred quid, and gained you driveability, and around 3 miles per gallon? It'll pay for itself in a year or two!

If you're looking at an ECU repair it may well be cheaper to go OBD2 in the medium term.

[Kevin Bacon 5]

OBD2 is £150 - £250 in parts (depending where you source it), yes, but labour to fit it all runs close to £400, and £650 is DTA S60 money..... which you can splice into the stock loom and setup yourself if you're handy with crimps / soldering iron.

 

And in doing so you can lose the annoying MAF sensor and do yourself a nice 3D map using a MAP sensor instead. NA isn't difficult to map and with the DTA's self tuning feature, you'll be blasting up the road sooner than you think.

[Niges16V 0]

The DTA might be a plan (if I knew what is was!), don't mind spending a bit more to upgrade!

 

The fuel pump isn't kicking in at all. We got it running by shorting the relay but it still didn't fire. Besides, if it was the fuel relay then the others would still be kicking in wouldn't they?

[dr_mat 0]

Does your spoiler work? I heard that the fuel pump shares a fuse with the spoiler motor .. !

(Not that that would prevent 12v making it to the sensors from the ECU.)

 

What stuff needs replacing for OBD2 then? I was under the impression it was relatively simple, but obviously not if it's a good day's labour...

[Niges16V 0]

All fixed now :D

John @ JMR traced it to poor connections & wiring in a number of places which was effectivly starving the ECU of power. Not that serious after all, but obviously tricky to diagnose & fix for a novice like me.

 

Thanks for all your advice guys, so much more effective than a Haynes manual!!

[Critical_Mass 10]

Good news, nice one.

[bigpants baby 0]

All fixed now :D

John @ JMR traced it to poor connections & wiring in a number of places which was effectivly starving the ECU of power. Not that serious after all, but obviously tricky to diagnose & fix for a novice like me.

 

Thanks for all your advice guys, so much more effective than a Haynes manual!!

Im have exactly the same problems,could you give any more details as this prob is driving me kin nuts :nuts:

 

All sorted now,there is 3 white multi plugs in the back of the fusebox(for the engine harness) it turned out to be the middle plug,gave it a wiggle & "o happy day" :sunny: :sunny: :thumbleft: :thumbleft: :notworthy:

It was looked in place with that fusebox locking bar aswel?

So by the looks if your vr conks out check ign switch,fuses,relays 109,167 & this connector on back of fusebox

[VR6 0]

Hello mate,

 

Before you try anything else change the ignition switch. Mine refused to start, although it was turning over but not attempting to fire up.

 

Mine's currently having this problem.

 

Probably a stupid question, but if the car is turning over, how can the ignition switch be at fault for it not firing?

 

My igniton switch does need changing because you sometimes have to apply a little upwards pressure to get it to start. However, now it doesn't seem to fire at all.

[dr_mat 0]

Probably a stupid question, but if the car is turning over, how can the ignition switch be at fault for it not firing?

 

The ignition switch has more than a single switch. It has to separately turn on the ECU live circuit, and THEN turn on the big fat relay for the starter motor. One can work when the other doesn't, that's not hard. If your igntn switch is known to be faulty, start there before you look at anything else ..