Glow plug circuit intermittent

[Sher]

Hello

I had my check engine light come on and i got it scanned ( thanks Louis) the code was
Glow plug circuit intermittent the car ran fine about a week later the same code came up

any ideas what this could be? is it a bad glow plug?

Thanks

 

[valois]

Sher, you can check the resistance of each plug to determine what state they are in, 1.2 ohms is what you should see, but this sounds like a wire opening when it does not repeat immediately. CHeck the Glow plug relay and especially the terminals it plugs into to make sure one is not making intermittant contact.

 

[riddei]

I hope you don't have to go down the same road that I did.

My intermitent glow plug problems

Good luck

 

[Vin]

Same problem here.
Scanned by VAG-COM:
******ERROR MSG BEGIN*******

1 DTC's Found:
16764 - Glow Plug/Heater Circuit (Q6): Malfunction
35-10 --- Intermittent

****END ERROR MSG********

Riddei: Your link has one too many "http://"

Spec: 2001:Jetta:30k miles(yea i know)
I am going to try Valois suggestions and few other. Hopefully find a solution and post it.

 

[Army_Tanker]

I have a similar problem. Sometimes the glow plug light just doesn't come on and the car won't start. But it seems to only happen when it is raining/moist outside. I have to flip the ignition on and off untill the glow plug light comes on and then it is fine. Any Ideas??? I was thinking some wiring or a relay.

 

[Jimmy]

Very possibly the GP Relay - look for relay "180" if it is an A4 series. Its under the dash. Also check tightness of the terminal you find under there (Do not short them out to the chassis!), and the terminals on the top of the battery (two 50A fuses protect the normal GP circuit and the coolant GP's).

 

[MOGolf]

And you might want to check to see if you have the old relay 109. It supplies power to the glow plug relay, and could be getting flaky. Replace it if you've got the old one.

For further info see: http://forums.tdiclub.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=17&t=002518

 

[Douglas]

I was just getting on to post the following message when I found this thread. Here's my situation.

---

I have a 99 Jetta IV TDI with 70,000 miles and the check engine light has come on.

If I restart the car while the engine is still warm from driving (anywhere from 0-45 minutes after shutting the engine off) it takes 1-2 seconds of cranking for the car to start. Also, when this happens, if the sound system source is set to the CD player it resets to FM radio during starting.

When the engine is cold (even in below 40 degree weather) it starts without a problem and the sound system stays on the CD source.

Once the engine is running in either case, is runs fine.

I have VAG-COM hardware and software and the Bentley Manual. My car reports an intermittent error code of 16764, "Glow Plug / Heater Circuit Malfunction." The Bentley Manual say this could be cause by a bad glow plug relay or bad glow plugs.

I've replaced the glow plug relay (relay 180), which I've had to replace once before at 50,000 miles. I've also checked the interior fuse panel, battery fuse panel, glow plug harness and individual glow plugs according to the Bentley manual and everything checks out okay. I've also replaced relay 109 with the updated version around 40,000.

I figure it's an electrical problem and not a glow plug problem since it starts fine cold and because of the radio behavior, but I don't know what else to check and where to start looking. Does anyone have any suggestions? Your input would be appreciated.

Thanks,
Doug

 

[MOGolf]

Refer to the Bentley manual to find and check the ground connections. There are a couple in the instrument panel and near the steering column that appear to be involved.

I think there's been at least one reported case where the dealer replaced the glow plug wiring harness to resolve the problem.

 

[SoTxBill]

first off have the battery load tested,, then check for bad connection on both ends of the battery cable, then relay 109,, then grounds elsewhere..

while cranking the voltage is dropping soo low that its resetting the fm radio, and triping glow plug codes both while cranking..

you could have a bad cell in the battery but still can produce current.. so a load test will show this up.. make sure the voltage under load stays above 10.5 on the battery..

 

[Douglas]

Thanks TexasBill -- you hit it right on the head. Turns out the fluid level in my battery was extremely low and it couldn't keep up the current under load. I poured in some distilled water and everything is back to normal.