Electrical issues?

[crc_73]

Having some electrical issues on a 2002 Mk1 Leon, hardly surprising for a 21 year old I suppose, but seeing if I can make things a bit more reliable.,..

I've had some flickering lights in the cluster, mainly the handbrake, but yesterday the TCS light was coming on, but I don't think it was on as in an error, as it was dimmer than the others, like tthe one that comes on when the headlights are on, and it gradually went off over a 3 hour drive. It would fade, come back a bit, and eventually looked like it was off.

I sometimes have the issue where after turning off the ignition and taking out the key, the tach and speedo will light up.

This morning it got a bit worse. 15 minute drive to work, and the airbag light came on, but I think it's showing as a proper issue, as it comes on with the ignition switched, goes out, then comes back on again and stays on, and it's bright like the others, not flickering. Anyway, I got to work, parked up, and got the PC with vag-com to do a scan, but laptop dies on me, low battery. But when I switched on the ignition, none of the warning/indicator lights in the cluster would come on. If I tried to start the car, it would run for a couple of seconds and shut off.

I left it for about an hour, came back, and the lights now come on in the cluster with the iginition, and the car started and seemed to be running ok now, and seems to be running normally. However, the lights in the cluster are coming on, but the light behind the time, tacho and speedo are flickery. Sometimes some of the segments on the time and miles indicator look a bit faded.

So it seems to be an electrical fault, something to do with connections? Having read a few threads of similar issues, I should probably take the cluster out and have a look at the connections on that. But I also see mention of earth straps, where are they? I think there are a couple of them under the battery tray, but are there others that would need attention?

Any other insight on what to do or check would be appreciated. Thanks.

 

[MoToJoJo]

It's a common fault of water ingress affecting the electrics. Best case scenario is the water is getting into places, worst case, you ECU is about to go bye bye.

I think there's a fair few guides on what to check but afaik, check the ECU area and also lift carpets to see how wet the sound deadening foam is.

 

[Alexis27]

Also check the relays under the steering wheel. Pull them out and check the pins aren't rusty

 

[crc_73]

It's a common fault of water ingress affecting the electrics. Best case scenario is the water is getting into places, worst case, you ECU is about to go bye bye.

I think there's a fair few guides on what to check but afaik, check the ECU area and also lift carpets to see how wet the sound deadening foam is.

Thanks for the replies, just seeing them now.

The car was parked up for about 3 weeks prior to the start of my story above, and it was a wet 3 weeks. I did have a bit of water in the passenger footwell, under the scuttle plate was clogged with muck, so I cleaned that out.

Since last week, the car has been parked up at work. I was able to start it a few times, and even drove it around the grounds at work, and it drove ok. The lights in the dash cluster were still acting a bit funny. I did a scan with VAG-COM, and got a few errors.

18058 - Powertrain Data Bus: Missing Message from Instrument Cluster
P1650 - 35-10 - - - Intermittent
17978 - Engine Start Blocked by Immobilizer
P1570 - 35-10 - - - Intermittent

01176 - Key
07-10 - Signal to Low - Intermittent

00928 - Locking Module for Central Locking: Front Driver Side (F220)
27-10 - Implausible Signal - Intermittent
00929 - Locking Module for Central Locking: Front Passenger Side (F221)
27-10 - Implausible Signal - Intermittent

The car was starting before the scan above, but it won't won't start now. The battery is fully charged. When I put the key in the ignition and turn to the first stop, the dash lights come on ok, but when I turn the key further to start the engine, the engine doesn't start, won't even turn over. Is that the immobiliser kicking in?

It's a bit late to do a scan tonight, but I'll do one tomorrow, and see if I get anything different to the last scan.

I'll check the relays to see if they look clean, and the fuses.

I'll also check the ECU connections, I see posts here and elsewhere with similar symptoms saying to check this.

A quick question about the ECU, if it has gone bye-bye, is it plug and play, or does it need programming, do I need an ECU specific for this car, that is, same engine size, or any other criteria that have to be the same?

 

[Nam-uk]

There’s a good chance the seal under the pollen filter box has crumbled it’s the same seal used on the inner door panels as that causes leaks, easy job todo once cowl panel is off as it’s only fixed with two nuts, clean and reseal with butyl tape..
Definitely worth checking that as it’s a common problem, also under the battery tray there’s a few earth points also worth removing and cleaning up, some can be good or not it’s a lottery, once fit back put some grease on the points.

 

[MoToJoJo]

Yes, I think it's your immobiliser kicking in.

If I was a betting person I'd be looking at sealing the scuttle panel leak points as water is the problem.

ECUs are set to see certain parameters so it's better to replace like with like. ECUs are matched to the instrument cluster and immobiliser transponder in the key, so unless you have it de-immobilised you need those to be up and running

 

[crc_73]

There’s a good chance the seal under the pollen filter box has crumbled it’s the same seal used on the inner door panels as that causes leaks, easy job todo once cowl panel is off as it’s only fixed with two nuts, clean and reseal with butyl tape..
Definitely worth checking that as it’s a common problem, also under the battery tray there’s a few earth points also worth removing and cleaning up, some can be good or not it’s a lottery, once fit back put some grease on the points.

I did have that out some years ago, but cannot for the life of me remember if I used butyl tape, or silicone. There is a wire in that channel that has a grommet that I lathered in white silicone, so I might have done the same with the seal under the pollen box, as they were likely done at the same time. Strange that I would have used silicone, because I was probably doing the door seals around the same time with butyl tape.

If I do manage to get the car going again, I will go in there again and see what I did before, and fix if necessary.

 

[Nam-uk]

I did have that out some years ago, but cannot for the life of me remember if I used butyl tape, or silicone. There is a wire in that channel that has a grommet that I lathered in white silicone, so I might have done the same with the seal under the pollen box, as they were likely done at the same time. Strange that I would have used silicone, because I was probably doing the door seals around the same time with butyl tape.

If I do manage to get the car going again, I will go in there again and see what I did before, and fix if necessary.

silicone wont last if you did from day one you put it on, butyl will though

 

[crc_73]

Will do with butyl tape if I get it running again, still parked up, but I haven't had time to look at it since.

Quick question, when the key is used to switch off the car, and then removed from the ignition, do the two displays under the tachometer and speedometer also switch off, as in the time and outside temperature disappear on the left one, and the miles/trip on the right one? Is this correct behaviour?

 

[crc_73]

Just revisiting this, as I don't think the car is back to normal yet. I had an issue with the braided wire on the starter motor that went up in smoke, but I got a replacement from a breakers. and the car is starting and running now.

But when I was putting things back together yesterday (the starter motor, wiring, clamps, battery, etc.), when I first tried to start the car, I wasn't getting any of the normal startup lights in the cluster to light up when the ignition was turned to the first stop, just the clock and mileage indicators. If I then tried to start the car, it would turn over, run for a second or two, and die. I think that this is something to do with the immobiliser not communicating with the ECU, hence the no lights in the dash cluster. Would that be right?

However, I left the car for maybe an hour, came back out to it, put the key in the ignition, and the lights are now coming on at the first ignition stop, and going out if applicable, and turning to the next stop, the car starts and runs normally. I drove the car around locally for about 30 minutes this morning, and all seemed ok.

I didn't do anything to any connectors or anything else, other than let the car sit for maybe an hour connected to the battery, between it being a basketcase, and seemingly running ok.

Now, it's great that the car is running now, but the thing I'm concerned about is that the car had to be left for a while before it eventually (miraculously) began to run after the battery had been connected up. I've had batteries off before on this car, but before the start of this thread, I never had to wait for the electronics to "warm up", if this is indeed what is happening. The car would always run immediately after connecting the battery.

Does anyone know what might be going on?

I bought a second-hand ECU from eBay a few weeks ago, same part number as mine, just in case i needed it, but I had a look inside to see if there was any water ingress; it's dry inside, but I noticed a couple of capacitors on the circuit board, and wondering if these capacitors, or any other components on the board are going a bit faulty after all these years, and need a bit more time powered up to begin to start to work. I am familiar with capacitors in other electronic devices like power supplies for TVs and computers, and how they can cause issues when they go out of spec.

With this in mind, anyone familiar with what the ECU and dash/cluster specialists do to revive these parts? If I was sure that my issues lie with the ECU and/or dash/cluster, I would bring them somewhere to get them properly tested, and parts replaced if possible.