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1978 Silver Anniversary, can't figure out where the rear defrost relay and the drivers side courtesy light mount. Would appreciate any help.
Rear Defogger relay is probably behind the drivers dash above the headlight switch area. You'll need to remove the left dash vent duct for the A/C to see up there. Do the courtesy light while that A/C duct is off.
I say "probably" because it depends on if your 1978 is early or late production. But there isn't a breakdown of this by serial number. Basically the 1978 model year had many changes during the model year. The main harness behind the dash change during the model year which mean things like the defogger got moved to the rear of the console like 1979's have. One thing you can check to be certain of the relay location is pull the door sill trim plate, pull up the edge of the carpet, and if there is a thick purple wire in there that's coming from the defogger relay mounted where I described it and going to the rear window grid. When the relay was relocated to the rear of the console the purple went across the bulkhead behind the driver's seat.
It is my understanding that the defogger relay was either behind the glove box (Late 1978) or above the steering column (Early 1978)
That photo above is of a 1979 part number 527361, it also had the bracket for mounting.
The 1978 part number 527362 had no bracket.
Location for the early 1978:
I thought you got the upgrade kit for this working???
That would have required locating the relay...
I did get it working, but the relay was hanging there. I wasn't the one who had removed it from. It's correct position. I am just trying to put it all back like it's supposed to be. It is an early 78', the relay is hanging down underneath the steering column.
I did get it working, but the relay was hanging there. I wasn't the one who had removed it from. It's correct position. I am just trying to put it all back like it's supposed to be. It is an early 78', the relay is hanging down underneath the steering column.
I sometimes come off a little harsh, I don't mean to...
So what did you do to resolve the up-grade kit issue? you never responded back...
It may help others in case there was a step or something you missed from the instructions you received with the kit.
All I did was follow your advice. I followed the upgrade instructions and still didn’t have any power going to the relay or switch. There was a couple of orange wires coming off the relay plug. I ran a wire from the 30amp breaker to one of the orange wires and it powered up the relay and switch. I really appreciate the diagrams and help. I had been fighting with that issue for months, wouldn't have gotten it to work without your help. Thanks again.
All I did was follow your advice. I followed the upgrade instructions and still didn’t have any power going to the relay or switch. There was a couple of orange wires coming off the relay plug. I ran a wire from the 30amp breaker to one of the orange wires and it powered up the relay and switch. I really appreciate the diagrams and help. I had been fighting with that issue for months, wouldn't have gotten it to work without your help. Thanks again.
If you haven't buttoned it all up yet, could you take a couple photos so I can see what changes you made to get it to work?
My concern is if you used the unconnected Orange Wire from the 30 AMP breaker to the switch side wiring of the circuit those wire sizes are undersized.
The switched side wire sizes are protected or should be by that 10 AMP Gauges Fuse...
All of those are either #16 or #18 gauge wires, notice the 30 AMP circuit breaker Orange wire is a #10 gauge...
The diagram I posted on #8 is the factory 1978 Defogger circuit.
The Upgrade kit included a new Timer Relay & Jumper harness.
So your 78 Defogger circuit is now more like the 1980
Here is your updated 1978 circuit.
Notice, S39 (S=SPLICE) are connectors A & B on the instruction sheet.
I also included X & Z to there respected places.
Save this diagram...
Here is how i got the rear defroster ti work. The updated kit came with a relay timer and a pink wire. The pink wire goes inti the blank space in the plug. The old relay did not use this space. The orange wire with the red plug will go to the fuse panel. Then you take out the pink/black wire on the defroster switch and install the pink wire in its place. Plug the orange wire in the 30amp fuse tab. This gives power to the relay timer. Instructions for updated kit
You got it, that's correct!
Ah, but the new relay requires 2 power sources where the old relay only required the orange. The new relay requires the additional switched source (Pink Wire)
IF, that pink wire was removed from the new relay connector that new relay would NOT work....
So the problem was the orange wire was not plugged into the fuse panel.
If that orange wire was unplugged from the beginning it is likely you now have a good spare switch and relay,
I have been testing several relays, one from a 79 and one a vendor sells as the upgrade relay and one from a Jeep Cherokee...
