Ashton89iroc

hey guys, I've searched around on all the defrost threads here. problem is, i don't know a thing about how the defrost works...so i wouldn't even know where to start.

all i know, is that when i hit the switch, the light doesn't come on....ive read something about a relay? no clue what that is, or where its even at.

Maverick H1L

iTrader: (8)

The timer module is under the passenger's side of the dash... Remove the lower panel (not the one by the feet) and it's right behind there. It's got the big plug (if there is one with a smaller plug under there, it's the cruise module).

Ashton89iroc

would the timer module be the only thing causing it? if it is, what do i do once i get to the timer module? if not, what else should i do?

if the light isn't even coming on, on the switch...would that be a bad switch?

sorry if I'm coming off as an idiot, usually i can figure this stuff out on my own but wiring just stumps me.

John in RI

iTrader: (167)

Here's a diagram of the Defroster system in an 85. Your's will be similar,...... The "timer" is built into the switch itself.





In the early years the power source is tapped into the back of the fusebox IIRC. The later years I'm, not sure where the PINK / ORANGE tap into.

Probe the power wires for 12 volts when the key is turned and be sure ALL the grounds are intact and the hatchback wires still good. If your getting power and the grounds are OK than my first guess would be a dead switch.

Ashton89iroc

im not the best with wiring diagrams, but ill give it a shot this weekend...that way i have plenty of time to swear and complain!

I'm pretty sure i have a test light laying around somewhere. if the light on the switch won't turn on...doesnt that automatically mean its a bad switch? ....just a thought.

thanks!

Maverick H1L

iTrader: (8)

John's statement is incorrect... 87-92 used a separate timer relay box after the switch, and the system reverted to the single timer switch box in 93.

Once you find the module under the passenger's side of the dash, you need to turn the key to RUN and probe the orange and pink wires at the timer relay for 12V.

If both have 12V, push and hold the defog switch down as you probe the blue and purple wires for 12V. No power on the purple wire means the relay is bad. No power on the blue wire indicates either a bad blue wire between the switch and the relay or a bad switch. Also check that there is no resistance between the black/white wire and ground.

It's also possible that the lamp in the switch has died. To test, check for power at the purple wire on the body end of the driver's side hatch strut. Only after the tests above have been run.

Also check the resistance between the hatch end of the passenger's side strut and ground. It's possible the ground wire is damaged.

Ashton89iroc

excellent! that is exactly the answer i was looking for. thanks so much!

I just started to actually use my account on here in the past 4 days, and i have learned so freakin' much already.