Glow plugs issue

Westwindmk3 · December 2nd, 2019, 14:56

Hello everybody,
My car is golf 3 1996 TDI.
The problem is that the glow plugs indicator isn't showing on the cluster, no voltage on the wires to the plugs either. I measured current between 87 and 30, it's ok 12.5v. I measured 86 power from ignition is also present, 85 is about 6volts coming from the ECU. Fuse is also OK.
I'm really confused at this point. Are there any other components that interfere in the preheating system apart from the coolant sensor? I haven't measured continuity of wires from the relay to the plugs. that's the last thing I could go further with my knowledge.
Any other suggestions will be really appreciated.
Thanks.

Mongler98 · December 2nd, 2019, 18:35

i just saw a thread recently where its just a matter of getting the multimeter on really fast, something about voltage dropping really quickly.

Vince Waldon · December 2nd, 2019, 18:41

Find the fantastic multi-page "Glow Plugs 101 V2" thread and read read read..... lots of great info, pictures, etc.

Westwindmk3 · December 5th, 2019, 00:30

I tested all again, this time everything works as it is supposed to apart from the indicator light in the cluster. I'm sure that there is no problem in the cluster or the glow plugs bulb. Is the waiting period plug light controlled by the ecu or the relay?

Mongler98 · December 5th, 2019, 20:04

Quote:

Originally Posted by Westwindmk3

I tested all again, this time everything works as it is supposed to apart from the indicator light in the cluster. I'm sure that there is no problem in the cluster or the glow plugs bulb. Is the waiting period plug light controlled by the ecu or the relay?

it is, via the MAP program in the ECU, it can be set with VCDS to longer or shorter. (i think) or it has to be done with a tune, If i remember correctly, its done with VCDS.
you sure the bulb is still good???? its nearly a 30 year old car!!!

garciapiano · December 8th, 2019, 00:29

if the glow plug lamp doesn't come on briefly in the dash upon first key-on, your bulb is out. If the bulb is out you will also get a code stored for glow plug indicator lamp open circuit.

One way to test if the glow plugs are actually cycling is to disconnect the coolant temp sensor harness plug from the sensor located on the outlet flange (NOT the A/C temp switch on the upper radiator hose). If the coolant sensor is not detected by the ECU it will cycle the glow plugs for the maximum duration, with the corresponding light on in the dash.