90 Jetta 1.6L NA Glow Plug Light

[coke]

My glow plug light is always on. Never goes out. I've drained the water seperator, the fuel filter, ensured the tank has good clean fuel with no water to no avail. The only solution I found was disconnecting the plastic 3prong connector from under the trunk mat. That stopped the glow plug light from coming on when the key is on the RUN position but as soon as the engine is started, the light comes back on. If I short the two pins in the middle and the blue wire (not the brown), the light goes out and stays out but never comes on. I have tried removing the horn relay as suggested previously by a member of the forum, and tried a different relay. I have also ensured that the relay is in fact coming on, and it is.

Now, if someone can enlighten me, I have 3 sensors of the same two-prong plug type. Two are black, one is white. The two that are black are in the coolant flange directly in front and in between the two injectors on the flywheel end of hte engine. The white one is on the oppisite side of the cylinder head. The wires to that aren't hooked up at all. The two on the front of the engine between the two injectors are hooked up. Which one is the glow plug sensor plug? I've tried swapping the connectors around to all the different sensors, still no go. Any help is appreciated.

[Kudagra]

now bear with me Im working off an 86 model and Bentley book. German wiring sucks.

!st thing Id check is are the Glow plugs glowing? If so then what is triggering the relay. Try swapping in a known good relay. If swapping the relay dosent work check the wires going into the relay. 1 should be Battery power (on with the Key off). Then you should have one wire you can trace back to the Glow Plugs. Probably physically across from the Battery wire. Next there should be a wire that only is powered when the key is on (but should then shut off when  a timer breaks the circuit) The one physically across from it should be a ground.

Looking at the manual it shows a Engine Oil Temp Sender connected to the Glow Plug Relay. My manual says its Blue/white tracer. Also looks like the Water Seperator Sender does too. Probably no help but hey...you can always jab out the light with a screwdriver.

[coke]

Interesting. Hooked a test light up tonight, even with all my sensors for coolant temperature disconnected, the glow plugs do not cycle off until the engine is started. In other words I could leave the key on for 10 minutes and they wouldn't go out till it was started. After the engine is started, the car runs as usual, and 3 to 5 seconds later the glow plugs kick off. I think I have a faulty sensor.

I removed both sensors from the front cooling flange and cleaned them up a little and reinstalled them, then added the coolant lost during the process. Now, the engine temperature gauge isn't coming up where it did before, which never has worked right since the day I bought it. I think I'm probably going to wire the plugs up manually with a switch so I can control them, and take the relay out. The light is out for now anywho. Its hard to say what the previous owners did, but I'll figure out something I suppose. I'd like to know why the temperature isn't coming up on the gauge like it should though, I didn't change anything with the sensor.

[Kudagra]

well find out what wire feeds the gauge signal and ground it. If the gauge is good it will peg. If not its the sender or the wiring.

VW electrical systems run on FM... F*cking Magic. I have no Idea how not having the wiring hooked up on the right front power window will make all the turn signals flash when you honk the horn. But its messed up like that.

Ive rewired a few old VW bugs just because the wiring is gayer then the BrokeBack mountian guys having an orgy with the Queer Eye guys.

[coke]

Well I've solved the problem, at least in theory. I located the wire that runs the glow plug light on the dash in the dash connector harness and cut it. Im going to wire the relay and all associated components up in the engine compartment. I actually drew a diagram with MS Paint that outlines where all the wires for each terminal are going to go.