Cold weather&glow plugs only light for 1 second!!

H E L P!!!!!!!
The tdi wouldn't start the other day as the glow plugs only lit for about a second and went out.
Finally after turning the key rapidly on and off about twenty times it lit up and proceeded to pop and cough heavily for about 30 seconds!!

Anyone have any suggestions as to what I should fix or take a look at?????????

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Gas burners are for wimps!!!!!
Protect our constitution from liberal lawmakers!!!

What was the temperature outside, and how long had the car been sitting? In other words, how long SHOULD the glow plugs have come on?

If they should have come on for several seconds, but didn't, the prime suspect is the coolant temp sensor. It's possible (in fact, likely) that there are two coolant temp sensors - one for the gauge on the instrument panel, and another for the ECU.

This is NOT a relay problem. The glow plug light is straight off the ECU. If the glow plug light doesn't come on, the ECU isn't even TRYING to use the glow plugs.

Brian P.
'96 Passat TDI

[ July 05, 2001: Message edited by: mbciii ]

Thanks for the replies! It was a first start on a 18F morning. It glowed like 8-10 seconds when new under the same cold starts..
Do you know a simple way to check the sensor(I have a V.O.M.) like an ohm spec or something.
I was wondering if maybe some bad glow plugs may be at fault also????
Thanks for the help

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Gas burners are for wimps!!!!!
Protect our constitution from liberal lawmakers!!!

FL60cummins, I have no info on coolant temp. sensor specs., but I am pretty sure that your glow plugs are likely to be OK. When the glow plugs in my 1982 diesel Rabbit died, the glow plug light would still light for its normal interval, but then the Rabbit would still be very difficult to start. In general, Rabbit glow plugs lasted me about 4 years, regardless of mileage. I expect that the new, improved TDI glow plugs would last longer than that.
[edit:] Oh yeah, I forgot: if you have your VOM handy, you will find that the glow plugs appear to be d@mn near shorted to ground. This is normal. Don't forget that they do draw lots of current for the few seconds that they are on. A bad glow plug will appear to be "open" or have higher resistance than normal. Usually, if you find one or more bad glow plugs, you may as well replace them all since they have a finite lifespan.
You are correct to recognise that if your TDI does not fire up at the first try, you need to find out what is wrong.


[This message has been edited by cars wanted (edited December 08, 2000).]

Prog,

Next time the car does that, see if it will crank. Your ignition switch might be heading south, the contacts seem to get doubtful after a while.

I fixed mine by spraying WD40 into the keyhole until it wouldn't take any more. That was a year ago, and it's been fine since.

Brian P.
'96 Passat TDI mit UPsolute

GoFaster:

The car cranks fine, just behaves as if the glow plugs aren't warming up. Since the light doesn't come on at all that's what I would assume is happening.

The first time it did this it was around 32 degrees and I had to crank it (in 20 sec max bursts) about 4-5 minutes before it started. Then it ran like a champ. But, I had not completely removed the key from the ignition either, just rotated it. Subsequent scanning of this forum for the last 2-3 weeks led me to believe that I might have to "fool" the car into thinking that I had just gotten in before it decided to use the glow plugs.

I am unsure about the level of "smarts" in this car, being a programmer by profession it would seem to be too much trouble to accomodate all the sensor input information that some of the members around here believe is involved in getting the glow plugs to come on. My natural incredulity stops just after sensing whether the key has just been inserted. Weight on the seats, door being open then shut, etc... are too many things to go wrong. People would be upset if the glow plugs would not come on just because the under-seat weight sensor failed or had a broken wire.

Thanks for the idea though, if it gets worse as the temperature decreases it will be another thing to try.

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'96 Passat TDI
1 GHz Athlon Thunderbird

My 96 Passat does something similar. I just bought it used about 3 weeks ago.

In mine the glow plug light does not come on at all (3 times, all early on coolish mornings) but when I completely remove the ignition key and wait about 10 seconds and try again a few times, the glow plugs will fire up and the car will start as if normal.

This is annoying, but I love the car. According to the previous posts, I guess I will have to look at the ECR or coolant temp sensor. My CD of the Bentley's manual is supposedly "in the mail..." so I will just have to wait.

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'96 Passat TDI
1 GHz Athlon

Happened again!

Had to remove the key and re-insert about 20-25 times this morning. Of course it was 17 degrees (F) too. And it did start, just not as fast as I would have liked.

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'96 Passat TDI
1 GHz Athlon Thunderbird

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by ProgMuscle:
Happened again!

Had to remove the key and re-insert about 20-25 times this morning. Of course it was 17 degrees (F) too. And it did start, just not as fast as I would have liked.

<HR></BLOCKQUOTE>

You need a new ignition switch. You can do a forum search and see where others have mentioned the Passat ignitions being faulty. Try what GoFaster suggested, spray WD40 into the ignition lock cylinder.

If the glow plug light is not coming on AT ALL, then the problem is in the wiring of the system. Since you can get it to work by fiddling with the ignition switch, I am led to believe that the ignition switch is the problem.

Good Luck!

P.S. I wonder why the Rabbit glow plugs only lasted 4 years. The plugs in my Mercedes were 10 years old w/ 90,000 miles before they started heading south.



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2000 Yellow New Beetle 1.9 TDI 5-speed
1987 Diamond Blue Mercedes-Benz 190D 2.5 Turbo (sold, but considering re-purchase)

The A-3 TDI's should have a fuse for the Glow Plugs, just like the A-4's have in several places. Have you checked them?

VeeDubTDI, the earliest Rabbits had "slow glow" plugs that ran about 30 seconds. Later Rabbits (such as mine) had "fast glow" glow plugs which worked for only 5 to 10 seconds at a time. It is possible that "fast glow" plugs could fail more quickly since they operate more intensely, albeit for a shorter time. What type glow plugs did Mercedes use? Put another way, how long did the Mercedes have to glow before easily starting?
FL60cummins, you will have to resolve this very soon. By January, it will be too cold for your TDI to start without the help of glow plugs.


[This message has been edited by cars wanted (edited December 11, 2000).]

Well, I tried the WD-40, sprayed a bunch in and kept working the key around, just came out with a lot of graphite, yuuuchhh! The glow plug light would not come on at all this time. Of course I only tried about 50-75 times, it's too cold. I guess I will have to worry about it starting in the morning, praying must have a lot to do with it as well.

Sounds like I will need a new ignition switch.

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'96 Passat TDI
1 GHz Athlon Thunderbird

cars wanted, on the coldest of days, the car would preglow for about 5 - 10 seconds... fast glow.

Curiously enough, it wouldn't do a double-glow. If I turned the key off and then back on, the light would come on and immediately go back off (maybe .5 seconds).

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2000 Yellow New Beetle 1.9 TDI 5-speed
1987 Diamond Blue Mercedes-Benz 190D 2.5 Turbo (sold, but considering re-purchase)

Hummm, the graphite may have worn out the contacts in the switch over time. It was worth a try. Do you have a block heater or a heated garage for your car?

If you absolutely need to, you can hot-wire the glow plugs directly to the battery. I would only recommend this in an extreme emergency. It will work though, if you need it to.

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2000 Yellow New Beetle 1.9 TDI 5-speed
1987 Diamond Blue Mercedes-Benz 190D 2.5 Turbo (sold, but considering re-purchase)

Another idea, although not so swell... you could always leave the car running overnight. You'll only burn a few gallons of diesel.

I wouldn't recommend this one.

Thanks big time for the posts, i went outside and started unpluging sensors until I got the one that made the plugs run. It is on the top coolant hose that goes to the radiator. The sensor is the one that is closest to the head....strangely, it also makes the coolant temp gauge not work also. I thought they were seperate?? Not sure what the other sensor does.....?
However I still must need to replace a glow plug or two as the car still stumbles at first after a normal glow sequence
But at least I know it will start!!

Thanks again !!

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Gas burners are for wimps!!!!!
Protect our constitution from liberal lawmakers!!!

You may not need any glow plugs. You disconnected the dual sensor for coolant temp. for the ecm and for the gauge. It assumes a certain valu. That's probably why it stumbles. Replace that $25 coolant sensor.

(Weird though, how the thing can fail like that without any light. Maybe the contacts are just corroded and it'd work if they were brightened up some.)

Well, the dealership is now telling me that it was the ECM and that it is covered under an 8 year - 80,000 mile warranty. They are supposed to get the replacement in tomorrow.

Does this sound reasonable to anyone?

I like the warranty idea, I just was not aware of any such coverage, but I won't argue.

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'96 Passat TDI
1 GHz Athlon Thunderbird