HELP! Diesel Vanagon won't start... Glow plugs won't turn on

[MarkWard]

Sorry I was asking about the main fuse box. I'll assume its the later fusebox with the H type fuses. To properly troubleshoot it, you'd need a wiring diagram for an 87 diesel Doka. Might be time to start scowering the internet.

Another option would be to add a glow plug light. The glowplug relay should control the time the light is on. I think I posted above how to pin point the glowplug wire at the relay on the early diesels. VW often uses the same wire codes and it may have continued on. Sorry I can't be of more help.
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[vandoka]

Mark,

So when you stated earlier in the thread to ground pin 87 from the glow plug relay, what does that look like?

I removed the relay and plugged in a wire to the #87 spot, grounded it to the chassis and turned on the key. No glow plug light.

Do I need to insert a grounded wire into the #87 spot with the relay in place?

I appreciate your help...and like i said it is more annoying than anything else that the light does not work...
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1987 2wd Westy "Vanny" 2.5 RMW Subaru
1987 Syncro Doka 1.6 TD swapped to AAZ

[MarkWard]

I'll look at my wiring diagrams this am and see if I can make a suggestion where to test. Voltmeters are handy, but I fix more electrical problems with a simple cheap 12 volt testlight. It looks like and icepick with a wire and an alligator clip.

First step will be to verify the glow plug relay is working the glow plug light circuit properly. A test light can verify this.
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[crazyvwvanman]

Pin 87 of the relay is not the pin for this test.
The glow plug relay uses a socket with a lot more pin locations than most relays need and has wires to 7 pins of the socket.
The glow plug light connects to pin "L" of the relay.

Mark

[Gnarlodious]

Do you have a voltmeter? Can you measure the voltage between the chassis and engine while the glow plugs are supposed to be on? Also the voltage between the chassis and battery ground terminal.
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Vanagon ’83 diesel AAZ w/Giles injection, 5spd 4.57R&P+TBD and a '78 diesel Rabbit

[MarkWard]

So, I'm looking at the Bentley for the 82/83 diesel wiring. When the glow plug relay energizes, it appears to supply a ground to terminal "L". So 2 tests come to mind. With the relay plugged in, with a 12 volt test light connected to power and the test light probe touching the "L" terminal. The test light should light and then go out after the specified period. This test should confirm the relay is not the culprit.

Second test would be with the relay unplugged and the key on, grounding the terminal "L" in the relay socket, should light the glow plug warning light in the cluster. The cluster is supplying power to all the lights. Grounds activate them.

The manual is a little vague between 82 and 83 for the wire color for the glow plug relay light. 82 shows the wire to be red with a white tracer from the relay to the cluster. The 83 diagram shows red with white tracer at the relay, but blue with green tracer at the cluster. It does not show a connector where the wire changes color though. Report what you find.

The auxiliary heater diagrams for 82 and 83 don't show a connection to the cluster. Again, you may need a later diagram and should have one on hand anyhow. Its really the only efficient way to troubleshoot electrical problems.
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[vandoka]

Thanks for the troubleshooting tips guys! I do have a voltmeter and checked the chassis to engine and chassis to ground when the key was turned for the glow plugs as Gnarlodious suggested. This did not produce any voltage.

I don't have a test light right now but will get one. Instead I tried test #2 "Second test would be with the relay unplugged and the key on, grounding the terminal "L" in the relay socket, should light the glow plug warning light in the cluster. The cluster is supplying power to all the lights. Grounds activate them."

This did not cause the glow plug light to light up.

The only other thing I changed during the swap was to install an EGT gauge. I may look to see if I may have created a loose connection on the instrument cluster.
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1987 2wd Westy "Vanny" 2.5 RMW Subaru
1987 Syncro Doka 1.6 TD swapped to AAZ

[MarkWard]

It’s easy to fold one of the copper current tracks when pushing the cluster connector back on.
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[vandoka]

Well after getting my test light and trying test #1 and test #2 neither test would result in lighting of the glow plug light. But the glow plug bus was still getting power and doing it's thing....So I investigated the instrument cluster.

Something up there was a bit loose because with the cluster removed from the dash and still hooked into the wiring the glow plug light would be on and off intermittently as I moved things around.

Eventually I got the light to stay on and put it all back together.

So thanks for the tips. Now I have a test light and bit more info. on how to pursue electrical issues.
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1987 2wd Westy "Vanny" 2.5 RMW Subaru
1987 Syncro Doka 1.6 TD swapped to AAZ

[11BC2]

Current flows through the ignition switch to the dash light and to terminal “L” on the relay, which provides the ground for the dash light.
The glow plug circuit on my 1990 European spec Doka works other than the dash light is inoperable.
Using a DMM, I inspected the “L” circuit for continuity; no short to ground and 1ohm from relay base to dash LED.
I searched for and found this thread, and someone else above mentioned that it was a defective ignition switch.
I’ll test that tomorrow.