Glow plugs not working.

Well my GPs haven't been working for awhile but now that its cold the car won't start so I started diagnosing it. When I got to the harness I was going to check for 12v at the end of it where it plugs into the GP when I first turn the key over (when the glow plugs should be on). I didn't even turn the key on and I'm getting 12v. What do y'all think should do next?

At all four sockets?

Remove the relay and try again. Might be two relays?

yea, definately sounds like your glowplug relay is stuck on ....never seen that before.
That means your glow plugs were on all the time so they are sure to be burned out and will need replacing.

Okay, so I've pulled all my relays and it's still showing 12v??? I would have to have a short somewhere, right?

With the harness unplugged, 12V at the terminal may be normal. The glow plug relay is not a mechanical device, but solid state. It is quite likely that the switching transistors have a small amount of leakage that will show 12V if you use a high impedance meter to measure it with the plugs not connected.

Try measuring the off state voltage with a load connected. Any load will do, such as a test light. I suspect you will see the voltage disappear when there is any load.

Turn the key on and look at the brightness of the test light. It should be dimmer than when connected to the battery as the glow plugs are only rated for 7V. It may be hard to measure this voltage since it is pulses of 12V that average 7V. A lot of meters can't read a pulsed voltage accurately.

HTH

Oops. Forgot them new TDI's have SS "relays".

tyler1022 said:

Well my GPs haven't been working for a while but now that its cold the car won't start so I started diagnosing it. When I got to the harness I was going to check for 12v at the end of it where it plugs into the GP when I first turn the key over (when the glow plugs should be on). I didn't even turn the key on and I'm getting 12v. What do y'all think should do next?

Click to expand...

How do you know this?

tyler1022 said:

Well my GPs haven't been working for awhile but now that its cold the car won't start so I started diagnosing it. When I got to the harness I was going to check for 12v at the end of it where it plugs into the GP when I first turn the key over (when the glow plugs should be on). I didn't even turn the key on and I'm getting 12v. What do y'all think should do next?

Click to expand...

oilhammer said:

How do you know this?

Click to expand...

How do I know what?

tyler1022 said:

How do I know what?

Click to expand...

What I highlighted in bold. How do you know your glow plugs are not working?

oilhammer said:

What I highlighted in bold. How do you know your glow plugs are not working?

Click to expand...

Bc my MIL has been on with GP codes..

oilhammer said:

How do you know this?

Click to expand...

Beat me to it.

What is the code you are getting for the glow plugs?

If it is suggesting that the glow plugs are dead, then the first thing to do is to check resistance on the glow plugs.

If they are dead, then you need to install the correct glow plugs. I don't know if the ones that are in your car are the correct ones so if it came to me, I would order them BY VIN from the dealer since there were many changes on your glow plugs.

tyler1022 said:

Bc my MIL has been on with GP codes..

Click to expand...

OK, good, just trying to make sure you were not going after a hard cold start issue and blaming the glow system (lots of folks do that).

A simple Ohm check of each plug while in the engine is all that is needed. Most of the time, they are either good or bad, and unless you let ALL FOUR die, you'll see the difference in the bad one(s).

In the case of the BEW, you need to understand the whole fiasco regarding the plugs, and make sure you have the correct ones in your car AND if necessary the correct software. VIN will not help here, because they all have been changed since the car left the factory. The originals are NLA, and have not been for a decade now.

oilhammer said:

In the case of the BEW, you need to understand the whole fiasco regarding the plugs, and make sure you have the correct ones in your car AND if necessary the correct software. VIN will not help here, because they all have been changed since the car left the factory. The originals are NLA, and have not been for a decade now.

Click to expand...

But won't they be able to tell if the software has been updated? Or am I being naive thinking VW has their ducks in a row?

There is no way to look up a part for a car based on VIN and tell if that particular car has had any updates or recalls, if that is what you mean. The service department and the parts department are two different things.

And even if you DID have them run the VIN in the service department, that does not mean someone outside of the dealer network hasn't done something.

I have PD ECUs reflashed all the time outside the dealer, including my own PD.

I feel like the whole BEW/BHW/BKW glow plug fiasco gets played out and explained every year. Someone just needs to make a sticky so we can just point to that every time it gets asked.

MOGolf created a thread ages ago that details all the BEW GP recalls; software and corresponding part numbers are also included.