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When you start the car and tap on the brakes the rear wiper arm turns on. I have literally disassembled the interior trying to find a shorted wire, bad ground, dirty plug, etc. I have also pulled the rear bumper cover and pulled the tail lights apart to see if there was a short in them since some of the wires and grounds seem to run to both.
I have changed out to a new relay, swapped wiper motors, checked the brake light switch, changed the actual switch(which is new), completely pulled out and cleaned all the contacts and plugs on the CE panel. While i was in there I cleaned all the wires and ground spots behind it. I thought i had found the issue once or twice. First there was a little bit of corrosion the end of they relay. I cleaned that and the corresponding wires(also changed out that relay), but to no avail. I have traced every wire I could find that goes from the CE panel back to the license plate lights. All the wires are in great shape... they are all very pliable and almost like new... Yes even the ones running under the headliner that go to the back hatch and third brake light.
What am I missing or has anyone ever had this issue. I don't have the option to just unplug the rear wiper or get rid of it since my friend is trying to get this back to 100% working order.
Thanks for your time and any suggestions you may have.
what happens when you unplug the wiper switch?
NOTE remove the left console cover and trace the wires to the rear wiper switch connector disconnect the switch.
maybe you have the brake light connector plugged into the rear wiper switch
other thing to check is the back of the CE panel check for melted gray wires
NOTE wires that saw heat will have a satin finish to the insulation instead of a matte finish
Mrmerlin
That was one of the first things I did was unplug the switch. Sadly it does exactly the same thing, after holding the brake pedal down for a few seconds the rear wiper motor activates. When I pulled the CE panel out I didn't see any melted wires whatsoever. They all looked good and not burnt, but I will go back in there to see if any of them look discolored at all.
please post a picture of the brake lamp switch with the wires connected to it .
what happens when you press the rear wiper switch with the key in the run position
next thing is that the power wire for the wiper is tied into the brake light harness.
probably in the back of the car at one of the tail lamp harness connectors or in the spare tire well
Yes sir, all the lights work. When the key is on and you press the wiper switch it works as it should. It cycles 4 or 5 times and shuts off over in the correct "park" position.
The lamp control unit is between the brake switch and the lights. Try unplugging it and pressing the brake peddle, if the problem has gone away you know it's further down the line. Apply power to each of the brake light output pins and see if one side or the other triggers the wiper. This might help narrow down the issue.
Another question, does it only happen once after turning the key, when the control unit is doing a bulb check on the brake lights, or does it happen every time you press the pedal?
The lamp control unit is between the brake switch and the lights. Try unplugging it and pressing the brake peddle, if the problem has gone away you know it's further down the line. Apply power to each of the brake light output pins and see if one side or the other triggers the wiper. This might help narrow down the issue.
Another question, does it only happen once after turning the key, when the control unit is doing a bulb check on the brake lights, or does it happen every time you press the pedal?
Gazfish
With the lamp control unit disconnected it does not do it, I have also replaced the lamp control unit with the one out of my 86 and it does the exact same, obviously then the tail lights don't work either. With a power probe I have put power to the light bulb socket and it kicks the wiper motor on... I have not shot power down each of the input pins( I will do that shortly). As far as the brake pedal, it activates the wiper motor no matter how long the car has been running. Each time you depress the pedal the wiper starts up.
from this i would suspect the wiper power wire is tied into the brake light circuit,
now you have to find it,
i would start at the back and inspect the wire harness see what color the trigger wire is that goes to the wiper relay then trace it
02-05-2018, 12:27 PM
1986 928 rear wiper problem (updated)
