Does a 1988 Mustang GT Convertible have a Rear Window Defoger? - Ford Mustang Forum
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post #1 of 5 (permalink) Old 06-01-2011 Thread Starter
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Does a 1988 Mustang GT Convertible have a Rear Window Defoger?

Does a 1988 or a 1990 Mustang GT convertible have a rear window defogger? The reason I ask is I have found a black female-end connector on the dash harness while doing a dash swap and do not know what it attaches too? The dash swap I did was a 2005 Mustang dash into a 1990 Mustang GT. I also did an engine swap (4 cyl to V8) in which I used the engine harness which led me to use the dash harness from the 1988 Mustang GT donor. I'm in the process of trouble shooting my convertible top and found the connector without anything attached to it. From the 1988 wiring schematics it shows wiring for raising the top up and down going through a rear window defogger relay/circuit breaker. The colors of the wiring for the convertible top shows that it routes through the rear window defogger relay, but I don't have the donor vehicle to verify whether or not a convertible had a rear window defogger. I do have the HVAC controls and didn't see a selector on it for rear window defogging. I didn't think the convertible had a rear window defogger.

If a 1988 Mustang GT does have a rear window defogger, does anyone know the part number or have a pic of the relay? On the 1988 dash, where would the relay be located? I've tried going online to Napa and am having no luck in finding a replacement for the one that I have missing.

I'll be trouble shooting my convertible top wiring tomorrow and will take a picture of the connector.

Appreciate any assistance anyone has on this one.

Semper Fi,

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post #2 of 5 (permalink) Old 06-01-2011
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as long as the rear window is actual glass, then yes, it has a defogger.

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post #3 of 5 (permalink) Old 06-01-2011
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FWIW:..... In the 89 Mustang Shop Manual it show the rear window defroster or the convertible top switch being just below the hazard switch.

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post #4 of 5 (permalink) Old 06-01-2011
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Rear window defrost was not available on Fox convertibles.

The plug was still in the main harness and the switch was still in the dash, regardless.

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post #5 of 5 (permalink) Old 06-02-2011 Thread Starter
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pics and TM reference material

Thanks for all your responses. I am pretty sure now that I didn't have a rear window defogger control relay. If I did, it didn't do anything for me nor did it complete the circuit for the Convt Top Switch.

Regarding my Convt top switch; per the 1988 Mitchells TM Wiring Schematics the power for the switch comes directly from Fuse #5. I didn't get the chance to inspect and test voltage at Fuse #5, but will be doing that first thing tomorrow. If that's good I will be testing the conv top circuit breaker and lower/raise relays for continuity and voltage, followed by jumping wires to try and raise/lower the top.

I've attached some pics of the Tm of the Rear Window Defogger Control Relay and Switch for anyone that might want it for future use. Also attached, a pic of the Convt Top wiring schematic. The other two pics are the !@# connector that has been wasting my time and giving me grey hairs.

Semper Fi and thanks for yalls help.

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