Rear Defroster Inquiry

[bento]

i just got done reading the thread where you guys did the collective sluething on jack olsen's car and i have an inquiry .

i have an 88 carrera and the rear defroster doesn't seem to be working. originally, the light on the center console went out, so i replaced the fuse. the button returned to being illuminated (brighter when "in use") but the rear defroster still appears to not be working.

any thoughts electrical gurus?
relay? bad connector?

thanks

db

[james85uk]

This happened to me and when I looked under the rear glass rubber, the 'printed' wire on the glass near the connector had a break in it. My cure, so far sucessful was to slip a tin-snip of a beer can under the rubber over the break!

[Early_S_Man]

bento,

There are two areas to investigate ... back in the engine compartment on the fuse/relay/ignition coil 'console' or panel on the left fender inner panel.

1. The #3 fuse, which is rated at 25 Amps.

2. The large, rectangular two-stage relay, p.n. 911.615.115.00! The contact numbering is:

86a 31 86
87a 87 30

With ignition on, you should have +12 Volts at pin 30 of the relay, and with the defog switch operated all the way out, +12 Volts should also be present at contacts/terminals 87 and 87a, as well as the two positive leads of the window wiring ... both of which are Red/Black wires.

As always ... all of the brown ground strap wiring should be checked for loose or corroded connections!

Broken traces of the heating grid can be repaired with conductive silver paint, which is available at most electronic supply stores.

Good luck!

[rstoll]

340 'Cuda? Is this a new addition to the family?

[cary]

Warren, can I test the window grid for continuity ? If so, can I do it right on the window surface ? Don't really want to peel the rubber back to get into the end of he grid.
Would like to make sure it works before I pull the rear glass.
The PO didn't put the harness back in when he painted and changed the rubber. I have the harness. And the signals are correct coming out of the relay, at both stages.

TIA

MOPAR.......... The only muscle car I would like to have........70 AAR Cuda, 340 Six Pack .......4spd. In the only GOOD color. WHITE. LOL. Some day.

[Early_S_Man]

Robert,

Not exactly ... when the holidays roll araound this year, it will have been in 'the family' 32 years!

It got hardened valve seats in '87, along with headers and a 3" 'H' pipe fabricated by myself. Dual stainless 'turbo' mufflers quiet it down to a reasonable level, but it sets off car alarms up to 1/4 mile away at mall parking lots when started up!!! Completely stock, it still carries a Carter AVS 4-bbl, 10.5:1 compression, and runs well on 92-octane summer-mix Shell gas, not as well on the winter-mix crap!

Koni's all the way around, and 15 x 7 wheels under the stock fenders ... 215/65VR-15s in front, 245/60VR-15s in back!

Cary, yes, you can test the traces with blunt or rounded test probes ... just be sure they aren't sharp enough to pierce or scratch the traces! Usually, though, you can see the broken traces from inside the car if the low sun is visible out the back window, because when they crack, you will be able to see a visible gap when backlit!