Leon, Mk1, Electrical Issues

[tmcwboards]

Hi, have dropped by this site for a while now, after being sent here from searches with previous issues, but have come up against a problem which is pretty bad.

Car is a 1.4 petrol, and some weeks ago while driving to work, I think that's when the airbag light first came on. I parked the car up at work, and switched off the ignition, but when I turned the ignition on again, the lights in the cluster (airbag, ECU, handbrake, etc.) wouldn't come on. I left it for a while, maybe an hour or two, and the lights magically came back on. Car started ok, I drove around, but the airbag light still stayed on (on ignition to the first stop, the light come on, like the other lights, goes off, and then comes back on, and stays on).

Before I go further, when the cluster lights were not coming on, if I tried to start the car, it would start, but die after a second or so. Also, I could still open the car with the central locking.

I had an intervening problem with the starter motor between the above and now (braid wire on the motor burned up on me), but that is replaced since last week, and initially, after installing the motor, and reconnecting everything, including the battery, the car once again wouldn't light up the lights in the cluster, car would start and die, like before. I left it for an hour or so, and after switching the car on and off a few times to the first ignition stop, the lights suddenly came on, and I was able to start and drive the car. This was last Wednesday. On Thursday and Friday, I drove the car around close to work for about 20-30 minutes, and other than the airbag light, everything seemed ok. Just after I pulled up after the drive on Friday, after switching off the car, I tried to start it again, and it was back to no lights in the cluster at the first ignition stop, and start and die of the engine.

I left the car there for the weekend, I was able to access the car yesterday through the central locking, put the key in the ignition to the first stop, and no lights in the cluster (didn't try starting the car, as it will probably only start and die). So I turned the car on and off to the first ignition stop, 3 or 4 times, and on the last try, the lights come on in the cluster, and I am able to start the car! I didn't drive it yesterday, nor today, but it started fine for me today (airbag light still on). So from the above, it's hard for me to trust the car without checking some things further, or eventually bringing it somewhere that it can be checked more fully.

Now, I'm not sure there really is an airbag problem, from what I've read around, it is something that needs to be cleared with a diagnostic tool, I think the issue with the airbag light came because of some electrical issue, or communications between the ECU and the dash cluster? I don't know, but if anyone has any insight of what I should be looking out for or checking based on the above, I'd appreciate it.

Thanks.

EDIT: One other thing, which might be important, is that when the cluster lights are not coming on with the ignition to the first stop, when switching off the car and taking out the key, the LCD panels under the speedometer and tachometer also go completely off. When doing the same when the cluster lights are coming on and off normally, the clock panel stays on, as it should.

[Crasher]

I would suspect either a dead battery or faulty ignition switch.

[tmcwboards]

Thanks for the reply.

The battery is only 6-8 months, so unlikely that would be at fault, so I've ordered a replacement ignition switch and will try getting that in next week.

Just a quick question: would a bad ignition switch also cause some lights in the cluster to light up when the car is switched off and the key nowhere near the ignition? When I take the key out, the part that shows the clock stays lit, along with the handbrake light, albeit much dimmer and is flickery, than when the car is switched on. Or is that some other issue?

[Crasher]

I fitted a Bosch S5 to Mrs Crashers Polo last March (warranty replacement from Euro Car Parts for the Varta that failed) and this Monday fitted another under warranty as it was totally dead and would not hold charge. Modern batteries are *****!

[mickeybo]

Theres a control relay on this vehicle which has 7 or 8 terminals which the ign switch is wired through. i would start by checking earths and load testing wireing

[tmcwboards]

I'm back again....

Over the past few months, I didn't get much of a chance to look further into this, but have done so recently, but still having issues.

I got a new ignition switch and replaced the old one. I'm not sure if it made much of a difference.

I also looked at the instrument cluster, took it apart, and I did find some of the solder joints for the two 32-pin connectors were broken, maybe 5 or 6 broken on one, 7 or 8 broken on the other connector, but I reflowed all 32 pins on each connector. The ones that were broken tended to be towards the outer edge of the circuit board.

When I had the instrument cluster circuit board out, I noticed that some of the through-vias have little specks of rust-like material on them, seem to rub away mostly with my finger, and might have taken away some of the solder mask, but I think the traces underneath these areas are intact.

Anyway, after replacing the ignition switch, and reflowing the pins on the two connectors, I put everything back together electrically. The first thing I noticed was that the clock and milage/trip counters were not being displayed. I would have thought that with the battery connected, these should have been reactivated. It was only when I put the key in the ignition and turned to the first stop that they finally came on, along with all the other lights that normally come on. Turning the key further to start the engine, and the engine started ok, and would run.

I turned off the car, and left it for several hours, checking on it now and again, and the clock and mileage/trip counters stayed on. When it got dark, I began to notice that there is a bit of a flickery red glow around the clock display. Before, I was having issues where this was much worse, and some of the other lights, like the ABS light would also light (not fully), but that seems to be better now. But the car would still turn on/off the normal lights when started.

But occasionally, when turning off the car, either from the first stop, or from the engine on, the clock and mileage/trip displays will disappear, and when this happens, the airbag light will come on. When the key is turned after this happens, the lights usually come on, and the engine will start, but 1 time out of 10, the lights might not come on, and while the engine might start, it will cut out. When I scan the car, I will usually then have an "immobilizer message" error, and drive train error, and the airbag error, and I can clear them all, and if the clock and mileage/trip displays stay on, the fault codes will stay away.

So, I still wouldn't fully trust the car yet.

I'll have a look for that relay that Mickeybo mentioned. When I had the cluster opened, I noticed a few capacitors on there, could they be faulty? I know from working with TVs and some other electrical equipment, bad capacitors are often the issue. Even been shown to be an issue in instrument clusters?