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Rear defrost grid no-go, but fuses/switch fine-what's up?

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I guess I just want to be sure I am doing this right...

 

Rear window defrost grid ('87 GL Wagon) does not defrost. Hooked a multimeter at the right and left connectors after removing them from grid on window. There is no voltage across these two connectors.

 

However, the dual 15amp fuses are fine at the fuse box and the switch lights up, as does the glyph on the dashboard.

 

Is there any other fuse/? I ought to be looking at? This seems so simple: all electrics are "there" but no joy at the rear glass.

 

Many thanks!

John

Not sure where it's located, but there's a relay for the rear deffogger. Sounds like it could be your problem.

Do you hear any sound of a click, other than the switch when you push it? If not, I'd bet it's the relay.

  • Author

I knew there had to be something else - anyone have any idea where that relay might be located?

 

Or, if someone has an electrical diagram I can go at that...

 

John

use a test light clip to ground point to grid test each line until no light, that's where the break is, light should be dimmer as you go from side to side multimeter doesn't work

  • Author

Thanks Subiemech. It is not the grid per se, it is the current to either connector at either end of the grid itself. There is no juice at these connetors, but there is at the switch and at the fuses (that is, they are not blown...).

 

I have fixed my Targa rear grid using the paste you refer to. That does take a bit of skill!

 

Many thanks,

John

  • Author

Sort of a bump - there does not appear to be a relay associated with the rear defrost? I looked at my fusible links and they all seem just fine (there are three).

 

So last call - does anyone know if there is a relay I ought to be looking for? The '88 manual's electrical diagrams don't seem to show anything...

 

Many thanks,

Jw

Sir J, my diagram does show a relay.

It's power is fed by fuses 17 and 18 in parallel

The relay coil and the dash indicator are powered by fuse 12.

You do not say what fuel system your car has

Why would that matter??

A Carb car in 87 with 4wd has no ECU

Others fuel systems do

The relay mounting may be different as they are above the ECU on fuel injected cars.

The relays will be mounted in clusters somewhere up above the st. col.

The one you are looking for has these colored wires

 

blue/white

red/yellow

white/green

blue/red

 

Relays may be interchanged to prove one is toast

here is what you are looking for

relayEA82.JPG

Sure hope this helps, would not want you fogged in.

I can scan the diagram for you if need be, email me

  • Author

I have the carb'd model, so no ECU.

 

So I should look somewhere above the steering column? Are the relays easy to get to (you'd think so!).

 

I'll poke around this afternoon and see what comes up.

 

Many thanks!

John

  • Author

Just for future reference....

 

The relays on the carb'd model sit just above the driver's left knee, above the fuses, in a small rack that features half-round clips that hold the circular upper section of the relay.

 

You will need to remove the lower panel, below the steering wheel. Three screws sit vertically into the panel above it, and three plastic screw-type "flower" holders must be removed on the lower section of the panel. Unplug an electrical block connection to have the panel fully away from the area, and reach up and left to access the relays.

 

The color coding matched exactly what was referenced by Skip.

 

To test a relay, you can swap out a known good one. Otherwise, I do not know what the resistance, etc. needs to be as I combed my manuals and there is no testing procedure for the relay.

 

Many thanks for you help,

John

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