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Old 07-28-2016, 04:53 PM   #1
Geoffyhil
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Default Warning lights all coming on together

Hello All,
I'm hoping that someone out there can suggest a possible reason for all the warning lights on our EOS to come on from time to time, stay on for a few minutes, then (except for the power steering light) go off again. The power steering light stays on for a further short period, then it also goes off.
Three VW dealers have examined the car, and cannot find any fault.
Sometimes this situation occurs on a short journey, sometimes on a long journey. There doesn't seem to be any correlation with weather conditions (I did wonder if water might be affecting the circuit).
Any suggestions will be gratefully received!
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Old 07-29-2016, 12:27 AM   #2
EosSydney
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Three dealers unable to find a fault says it's a very unusual fault or alternatively says something about the dealers!
If the warning lights come on, one would expect one or more error codes to be logged. I would assume that the VW dealers have scanned the ECU for fault codes, did they give any indication as to what, if any, error codes were found?

Cheers

George
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Old 07-29-2016, 09:06 AM   #3
voxmagna
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Quote:
Originally Posted by EosSydney View Post
Three dealers unable to find a fault says it's a very unusual fault or alternatively says something about the dealers!
If the warning lights come on, one would expect one or more error codes to be logged. I would assume that the VW dealers have scanned the ECU for fault codes, did they give any indication as to what, if any, error codes were found?

Cheers

George
Spot on!

Unfortunately there are many old school mechanics who want to be convinced a part is faulty - it is smoking, on fire or the car is stopped and they have to fix it to get it out of their workshop! Modern cars are complex computerised systems and intermittent faults can only be traced using diagnostics and a stored record of the fault. Even with that it can still be tricky, but at least it is somewhere to start.

There are exceptions to the fault diagnosis protocol - if the 'fault' is something that is considered normal operation. For example, let's say your ignition key or the switch kept turning off and on whilst driving. The car treats that as normal. I'm not saying that is your problem, but if there are no stored fault codes it could be something to look at. Normally you would expect the engine to cut out, but the control signal sent to initialize the instrument panel control module may be different from that which the ECU gets to run the car.
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Old 08-05-2016, 08:35 PM   #4
Geoffyhil
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Quote:
Originally Posted by EosSydney View Post
Three dealers unable to find a fault says it's a very unusual fault or alternatively says something about the dealers!
If the warning lights come on, one would expect one or more error codes to be logged. I would assume that the VW dealers have scanned the ECU for fault codes, did they give any indication as to what, if any, error codes were found?

Cheers

George
George
Thanks for your input - on all three occasions, the technicians reported that there were no error codes were found on the ECU.
Geoff
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Old 08-05-2016, 08:41 PM   #5
Geoffyhil
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Originally Posted by voxmagna View Post
Spot on!

Unfortunately there are many old school mechanics who want to be convinced a part is faulty - it is smoking, on fire or the car is stopped and they have to fix it to get it out of their workshop! Modern cars are complex computerised systems and intermittent faults can only be traced using diagnostics and a stored record of the fault. Even with that it can still be tricky, but at least it is somewhere to start.

There are exceptions to the fault diagnosis protocol - if the 'fault' is something that is considered normal operation. For example, let's say your ignition key or the switch kept turning off and on whilst driving. The car treats that as normal. I'm not saying that is your problem, but if there are no stored fault codes it could be something to look at. Normally you would expect the engine to cut out, but the control signal sent to initialize the instrument panel control module may be different from that which the ECU gets to run the car.
Thanks for your input. The three diagnostic checks have failed to detect any stored fault codes. I think that your suggestion that whatever is happening is being treated as normal is one to follow up. The light display coming on and then going off certainly doesn't seem to reflect any physical change in the car. I'm not particularly observant, but even I would have spotted the roof folding when the light came on!
Geoff
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Old 08-05-2016, 09:33 PM   #6
voxmagna
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When you first turn the key, all cars light the dash lamps for a couple of seconds first to allow you to check for failed bulbs, then they go out leaving only those on that should be on like alternator/battery until the car starts.

I don't want to get confused and assume what you said about the roof folding was in jest because I assumed you were talking about ALL the warning lamps. As I said they all come on for 2 seconds at key on for lamp testing and catching out those that remove their airbag or steering lamps thinking they can get around mot testers when those are faulty.

If your warning lamps are showing this same behaviour intermittently whilst driving, then I think your problem is in the key switch and related control modules. If there was an intermittent ignition switch or wiring connection that made the disconnect for just a few milliseconds, the instrument panel initialization sequence would be triggered but you wouldn't notice the engine falter. The same problem might occur if there was a bad ground wire connection and the ignition switch wiring was picking up interference.

Another possibility is your battery or dirty terminals. Old batteries can go intermittent, particularly after engine start and the engine compartment has heated up. You might think if that happened you would be losing the radio code, but the alternator will keep things alive. However the alternator output is very spikey and that interference could play havoc with electronics for those few milliseconds. Short duration intermittent battery faults may not trigger fault codes.
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Old 08-13-2016, 08:59 AM   #7
Geoffyhil
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Default Further thanks!

Thanks very much for your additional thoughts. I was joking about noticing the roof opening - when the fault occurs the roof operating warning light comes on with the others, but of course the roof doesn't open or close!
Anyway, I'll go armed with your suggestions when I next take the EOS to the dealership for investigation.
The last manifestation of the problem was a few days ago. We had covered about 50 miles when the sequence started, and the full set of lights stayed on for several minutes. As by coincidence we were approaching the VW dealership that seemed to investigate most thoroughly, I pulled on to their forecourt - and as I did so, all lights went out. And they could find no evidence of a fault code!
We're getting quite blase about the symptoms now, so much so that I'm concerned that there will be a real fault reported and we'll ignore it!
Thanks again - I'll let you know if the dealership eventually comes up with a solution.
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Old 08-13-2016, 11:25 AM   #8
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Intermittent faults are the worst kind and costly in time to fault find with no absolute guarantee. Sometimes, the intermittent fault can go permanent and that is the best chance to nail it. I assume when all the lights come on that the engine is still running ok?

All you can do at the moment is get somebody to explore my ideas but dealers replacing parts and modules without any guarantee of success can be expensive if parts are hard to get to. Start with the battery and ignition switch + wiring. Turn on the ignition, wait for the lamps to go out then somebody has to poke around the wiring and connections in those areas I suggested. Being able to bring on the fault is as good as having it there permanently and will make it easier to find. The other fault finders tool is the hair drier. Warming up and cooling control modules associated with the ignition and instrument display might find something.

Diagnostics won't find or report on every fault. This could be the case with the instrument control module which is giving out information rather than being actively involved in running the car. It's like the bulb failure monitoring. It reports obvious lamps like headlight, sides and flasher bulb failure but I doubt it reports any lamps used in the cockpit display which are probably leds and guided light pipes anyway.
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Old 09-04-2016, 11:03 AM   #9
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Sorry for the delay in replying, but we've been away on holiday and the EOS was securely garaged! I've had the battery tested by a local (non VW) dealer whom I trust, and he found it to be slightly down on voltage. So we've had it replaced, and (touch wood) no recurrence so far!
However, whilst we were on holiday in Spain, I discussed the issue with a Danish neighbour. He promptly 'phoned a friend, a VW employee in Denmark, who said there is a known problem with VAG models, with the alternator regulator failing to smooth the output, causing spikes and multiple problems. I asked the local dealer to check the alternator, and he could find no issue with output, even over an extended test, so let's hope the battery was the source of the problem.
P.S. My Danish neighbour suggested that I copy his approach to his MB - he has installed a diagnostic computer in the dash. But then he's an engineer who enjoys a challenge!
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Old 09-04-2016, 11:39 AM   #10
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The battery condition is everything on modern cars full of computers. When a battery ages its ability to crank weakens and its terminal voltage drops. At this point you might notice cranking is more sluggish than normal. You can test the battery with a voltmeter whilst cranking over the engine. If the battery voltage drops more than 3 volts it is no good. When you buy a new battery always look at the CCA rating (cold cranking current) and amp hour ratings. Always get the highest number you can fit in the battery box. I always choose the bigger battery with less warranty over the smaller battery with longer warranty.

All alternators put out interference pulses and so does the starter during cranking, that's why you need the battery. It is the battery and good terminal connections that smooth out the interference. I think it unlikely your alternator was causing the problem. Batteries are probably the most neglected items on cars these days. 3-4 years old and they should be replaced. Do the battery terminal voltage drop test on a new battery then repeat at the service intervals or let a trusted local tire and battery shop do it. Although QF will probably tell you you need a new battery!!
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Old 10-26-2016, 02:45 PM   #11
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Just to update you - we're now well over two months with the new battery, and NO recurrence of the problem!
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