Electrical problem, burnt wire found!!

[Rpmayne 0]

After roughtly 6months of very unhappy Corrado ownership, the local garage is going to tow the heap back to mine after having no luck finding why it won't start (turns over, no spark) then starts and intermittently cuts out.

 

A while ago the alternator energise wire shorted to earth. That was repaired but before I found that there was some smoke from the dash one morning.. That I found last night as the neutral wire running from the fuse box to the head light switch. According to the electrical diagrams all it does is earth the lamp within the switch. It earths nothing else, and even if something had shorted the feed side of the lamp, the lamp itself should limit the current.

 

This wire (after abit of research) being 0.5 must have taken over 20A for it to burn and brake as it has!! :shock:

 

I reconnected it and the light in the headlight switch turned on, tried starting the car and the running problems remained. The wire didn't get hot either so the cause has dissapeared.

 

I know this could be anything but anyone got any ideas? My next task is probably to check the fuse board as this took the current aswell, just don't remember the mk2 Golfs looking like such a birds nest.. Is this a sign of a quality hand built car. Move it slightly and half the connectors fall out for you. :? Saves time but putting them back will be a laugh. :(

[aposegil 0]

not to say u havent check this already but vr's have a immobiliser which sometime fails is u use a copied key or a new key from VW that hasnt been programed in

 

Also a guy at work that has a golf highline had the model/wire go which he had to have replaced from VW

 

just a few tips

[Rpmayne 0]

Cheers for the tips, mines got an aftermarket Laserline alarm/immobiliser which could be causing problems. That was one of the garages ideas to link it out and see whether that cures the problems until he saw the back of the fuse board. Apparently the alarm fitters have cut lumps of the cabling out so you can't just see for instance, red wire, black wire, red wire. Ahh, reconnect red wires and thats bypassed. Good so its not nicked just using scotch clips, wish someone had though! :lol:

[aposegil 0]

yeah but the VW ones are built into the ECU system from what im told and cant be cut out as i know four people with this system in their cars and they all have CAT 1 alarms and if they use a normal cut key the car will not run

 

just my 2p's worth

[Rpmayne 0]

Ahh, I didn't realise the ECU had an immobiliser. So has the door key got a chip in it? I recently bought a new ECU for the car, is it possible that this won't match up with orignal keys then?

[dr_mat 0]

Yep, quite possible!

The ECU is wired to a sensor in the steering column. If the sensor is still there, and you wired the ECU to it, it'll be expecting the keys to match, and it won't start otherwise. You'll need to get the keys done to the serial number of the ECU.

[aposegil 0]

yeah im not big vr expert :( but ive heard this prolem can cause none starts and kowing the guy here at work had it aswell it wouldnt suprise me

[Rpmayne 0]

Following what you've said I phoned up ATP electronics (ECU specialists where I bought the new one) and they said my particular ECU off a '93 VR6 doesn't have an immobiliser in it. The later ones do though as you say, and they do need coding as per the returned unit.

 

As all the sparks are dissapearing, they say its unlikely a coil pack or ECU fault, more a loss of supply to either. One to check is the ECU control relay. Maybe the short has buggered the fuse board and subsequently lots of other things. Spoiler doesn't work automatically since this either, not sure that relay is in the fuse board though?

[aposegil 0]

sorry mate but its not that ive got no idea :(

 

it might be the fuse box or relays but ull have t check all that

 

Also have you ask VW customer service if your ECU def doesnt have a immobiliser??

[Rpmayne 0]

Don't be sorry mate, well grateful for the help..

 

All fuses are ok, will check all the relays tomorrow then disconnect everything to have a look at the fuse box. Not looking forward to that. Honestly mines a complete mess. Loads of extras fuses have been fitted for something aswell, alarm maybe. Just hanging there on crimps, didn't move it much and one connector fell off. Unfortunately that wasn't the problem.

[Kevin Bacon 5]

Where are you based RPMayne? Sounds like your C is need of some Haywire or Stealth attention :lol:

[Mike Edwards 0]

Wow - someone else who has had the same proiblem as me!

 

The little wire in question melted the insulation off all the others in the lead to the light switch in my case though.

 

The resulting short to earth meant that when you turned the car over (cuts power to the lighting circuit) it would fire then immediatley cut out as power was respored to the lighting circuit which was shorted to earth by the melted wires.

 

Replace the lead (£75 3 years ago - might be cheaper now) and the fuel and relief relays (they will have got a bit warm) and the problem should be sorted.

[Rpmayne 0]

Cheers Mike, will try that. Any idea how yours was caused? Will go and check through all the relays now, and replace that bit of wiring. If not I might take you up on that offer Kevhaywire, I'm near Brighton on the coast.

[Kevin Bacon 5]

Ah, Brighton is about 3 hours from me! Thought you might be a bit more local....

[Rpmayne 0]

I've just checked all the relays and no problems, assuming the flasher relays need a load to operate as they didn't switch by just applying volts across the energise terminals, but not related to the car running anyway.

 

So all the relays and fuses are ok, split the fuse box in the car for a quick look and can't see any signs of overheating or damage. Quite substantial tracks, would take alot to damage them i think.

 

I tried disconnecting the damaged part of loom and starting to eminate any shorts there might be and it still won't fire. :roll:

[Henny 0]

this really does sound like an immobiliser fault to me.... :? At this stage, having checked all of the fuses and box as you have, I'd be extremely tempted to get the alarm/imobiliser removed by an auto electrician to be mega sure that it's not that which is causing you hassles...

[Rpmayne 0]

Yer, think I might get the alarm linked out as you say. Just took a spark plug out, earthed it on the -ve battery terminal and turned the engine over. Definitely no spark. Got a scope on the connector to the coil pack, supply is there when the ignition is on. No signals from the ECU though to fire..

[Rpmayne 0]

Just checked the connections to the ECU and all the earths and supplies are present when the ignition is on. What I don't understand now is.. its definitely pumping fuel, so the ECU must be getting all the running information to control that. So why is it controlling some things and not others? Maybe an ECU fault, going to send the ECU back for checking then if that checks out ok get the alarm looked at.

[Rpmayne 0]

Got the ECU back from the supplier, they found a fault 'track breaking down' which they repaired. Thought this was the source of the ignition problem so fitted it along with a new piece of wiring loom to replace the burnt cable to the light switch. Engine started, tapped abit, but settled down and felt really good. :) Fitted the stereo back in, drove to get some car tax then took it for a run.

 

Had been driving for about an hour in total with no problems... then the engine cut out, turned over but would not fire as before and have just got back from being towed home. :( This car has been sent by the devil to generally piss me off! :evil:

 

Just to top it off, tried starting it once we pushed it onto the drive and it started as if nothing had happened! :mad: