A short while ago I posted that I thought there was a possibility of an electrical problem with the Passat (1999 TDi Sport). Now I know for sure that something's wrong, but can only think of two possible causes.
What's happened is that many of the lights are out, front and rear - mostly on the nearside. If I switch on sidelights only, I get nothing at the front and one light at the rear on the driver's side. Dipped headlight works on the driver's side only, not the nearside. The car isn't fitted with front foglights, but only the driver's side rear foglight works. Full beam works ok on both sides, as do the brake lights and reversing lights.
Recently I replaced the rear lightbulb (the one that should come on and stay on as soon as you switch on sidelights) and it did work for a short while, maybe three or four weeks. The same bulb was replaced last year as well.
So - I think it's either a wiring problem or a fuse problem. I reached the limits of my electrical know-how when I replaced the rear lightbulb, so any suggestions or solutions will have to be very step-by-step! Thanks in advance.
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andymc
Vroom, vroom - mmm, doughnuts ...
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Are you saying that the bulbs are blown? or are OK but not lit?
You say you replaced one and it worked for a while, was the old one blown, or was it a concidenze, such as disturbing the bulb holder?
If the bulbs are blowing frequently, it will be either an alternator overvolting, or vibration in the light holders. (Is it a diesel?)
If the bulbs are found not to be blown, then it will be much harder to trace, could be anything between the fuses, switches, to lamps.
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Not much help but Passats (and all German sourced cars) only have the rear foglight on the driver's side enabled even though there is a rear foglight lens on the nearside. So that's one less problem for you!
With respect to the sidelights, place the indicator lever in the left turn position with the ignition off - the nearside front and rear sidelights should come on. Do the same for the right turn position and the offside front and rear sidelights should come on. If you get the same failures as in your posting then you know the bulbs are faulty. I think that you've just got blown bulbs. Get an auto electrician to check the output from the alternator - it may be too high thus causing the bulb failures.
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Update:
Had the alternator checked, it was running constantly at 13.5 volts, which I am told is "average". The bulbs were burned out, but a fuse was also out. My mechanic replaced the 5 amp fuse with a 10 amp fuse, which I hope is wise.
It is a diesel, but it's fairly smooth running as I use biodiesel almost all the time so there's a bit less vibration than there would normally be. Is that really an issue with modern diesels?
I had forgotten about the foglight, so thanks for the reminder!
So far, so straightforward. Thank you both for the input.
And now for something completely different!
Today on my way to work, the coil symbol started to blink on and off constantly after I'd been driving for a little under 10 minutes. On a Passat, this is the engine management fault warning light. I pulled in & switched off, then switched on after a moment to see if it would recur - which it did, about two minutes down the road. When I slowed down going into the 30 zone, the blinking stopped. On my way home, the same thing happened less than ten minutes into my journey. Again, I found that if I braked, the blinking stopped.
With this being a diesel, the engine reaches operating temperature after about 7 or 8 minutes. This may or may not be relevant! I checked the manual, but all it says is that this indicates a fault with the engine management system and to contact my local dealer. With such limited information, I don't expect a diagnosis on here but would still welcome any suggestions as to possible cause. I'm going to start by trying my local Seat dealer (whom I trust not at least to rip me off) rather than my local VW dealer (whom I don't) to see if their VAG-COM will be able to read the code. I'll post any feedback here, if only to add to the Backroom's ever-growing pool of information about Passat faults.
Wish I'd held out for a Rover 75 ....
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andymc
Vroom, vroom - mmm, doughnuts ...
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1) The fact that it's a diesel should have no bearing on the problem. I've had Passat diesels since 1996 and I've never replaced a bulb!
2) Check your brake lights - the glow plug warning light (coil symbol) comes on when either the brake light switch or stop light bulbs have failed. It's to do with the engine management system that that requires a signal from the brakes to prevent acceleration at the same time. Brake light switch failure is quite common on all VW's
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2) Check your brake lights - the glow plug warning light (coil symbol) comes on when either the brake light switch or stop light bulbs have failed. It's to do with the engine management system that that requires a signal from the brakes to prevent acceleration at the same time.
Is that why left foot braking or heel&toe always causes the engine to die when I try it on my Octavia ? I applied light brake pressure while accelerating to dry the brakes after passing through a flood last week, and irrespective of how much pressure on the hot pedal, the revs just fall away, and that's always happened when i've tried it in the past
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Sept 2004 - 'Britain on the Move'
curious ? see www.mikes-walks.co.uk
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You can't accelerate and brake at the same time on VAG diesels. It's apparently a safety device. To check your car:-
Start the engine, leave the gearbox in neutral hold the brake pedal down with your left foot and press the accelerator pedal to the floor with your right foot. The revs may rise slightly and then they will fall back even with your foot flat on the floor.
If the brake light switch fails a 'braking' signal doesn't get to the ECU hence the engine management light (doubling as the glow plug warning light) comes on. You could then, presumably, brake and accelerate at the same time - hence the warning.
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Where did you get the bulb from?
I recently changed a bulb, and the Halfords booklet told me to use bulb 382 from their selection. However, it turns out this is wrong bulb - you need a double-filament bulb rather than a single-filament (it's a combo stop & tail light).
Putting the wrong bulb in caused all sorts of strange things to happen, including lights not working when I knew the bulbs were fine and the sidelights coming on when the brake pedal was depressed.
The garage which did my MOT recently also believe that the wrong bulb may have caused an electrical fault which fried my battery - £130 for a new one!
Anyone else have any other thoughts?
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Forgot to say - the dual filament bulbs (there are 4 on each side!) in my 2001 Passat rear lights are very special and have differently offset pins. They are 21/4 watts and are not the same as standard 21/6 watt stop/tail bulbs. I think that they can only be got from a VW dealer. I'm not sure whether older Passats have these bulbs.
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Wow - I can only say hats off and well done to all those who replied - you have managed to cover everything my Seat dealer was able to tell me, as well almost telepathically identify the root cause of the problem!
This morning, I took the Passat to my Seat dealer, where they hooked the car up to the VAG-COM (with just 15 minutes notice from me that I wanted this done). The software identified what I think was called "irregular braking function" (sorry I can't remember exactly what it said). They also pointed out what I hadn't noticed, nor thought to check - that the front left sidelight was lighting up when the brake pedal was depressed. It turned out that when I went to - guess who - yep, Halfords! and asked for brakelight bulbs for a 1999 Passat, I was given a pack with a single contact at the base of the bulb instead of a dual contact. Having read the above about batteries, I guess I'm lucky that a blown fuse and some bulbs was the limit of my troubles.
The Seat service manager also pointed out about how using the brake will intervene to prevent the accelerator working and kill revs - just as described above. He even asked if I'd ever had any difficulty with heel and toe braking! Anyway, the wrong type of bulb seems to have been the cause of the earlier problems with the blown fuse and the second failure of a brakelight on the same side, as well as the blown sidelight at the front. When I had taken the car to my local mechanic to check for any electrical faults, he quite naturally replaced the blown rear bulb with the same type he had taken out - a single contact bulb. I guess the only thing to wonder about is why the engine management light didn't blink the first time a wrong bulb was put in.
So - congratulations to all respondents on making the right diagnosis based on scant information. As a thank you, virtual yards of ale accompanied by the short of your choice all round.
Also, kudos to my Seat dealer, who didn't charge me a penny for his time and has done well for me in the past, even though I bought my car from Holland. He will continue to get my repeat business for servicing, rather than me going elsewhere to save a few quid. IMHO this is an example of providing good customer service and maintaining customer loyalty.
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andymc
Vroom, vroom - mmm, doughnuts ...
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Thanks for the electronic pint! Glad it's sorted.
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