Every once in a while my rear lights will stay on with the car turned off and the light switch in the off position.

When this happens the fan motor will not work.

I then disconnect the battery, hook things up, and everything returns to normal and the fan now works.

Does anyone have a clue on this one?

 

Assumption1:
You expect the fan to run with the key off. You are probably referring to an aftermarket radiator fan.

Solution based on assumption1:
Wire the fan off the alternator (horn relay buss) not the battery. The fan connection may be tied to the stoplamps??

The stoplamp switch is always 12volts. If it sticks or is improperly adjusted, the lamps remain on.

Assumption2:
You have a coupe with a fan in the back.

Solution2:
the fan is shorted to the stop or tail lamps in the rear compartment harness.

 

Which lights are you talking about. Stop lights, tail lights or interior?

 

tail lights

 

Which fan motor stays on - radiator fan, heater fan, coupe rear vent fan....?

 

fan for front dash vent

 

Hey this is just off the cuff... Horn relay.... I think mine is going bad. I need to replace it but it has caused all kinds of wierd problems. I can have no power and press the horn and bingo.. Horn works then I can crank the car... It's only happened a few times all in my garage after I've working on the car.. Just food for thought... Dave...

 

Tail lamps out and heater blower motor runs with the car off? Serious problem. Unless the car has added electronics, my WAG is: main dash harness.

Tail lamps are fed off the light switch and don't use the bulkhead connector. Heater blower uses the bulkhead connector unless A-C is installed - even then it has a separate harness through the grommet behind the wiper motor.

 

Another funny thing since the interior is my last project to tackle...Interior lights and tail lights are run off the same circuit... Okay well every now and then my interior lights and tail lights don't want to work. I finally found that my drivers side door pin switch is in need of replacement. If I press it and release a couple of times the lights work.. Now this is just another little problem that I've seen.. It and the the horn relay are on my list of replacement items this winter... Don't know if this helps but the electronic problems in a midyear can drive you batty until you know how the circuits work and where to look... Dave..

 

Interior lights and tail lights do not share the same circuit(s) the door switches are simply grounding points, with the door closed the ground is held open, when you open the door the switch makes contact with ground and the light circuit is complete, thus light. It also connects to the head light switch and when you rotate the **** to the "click" part, it too grounds the white and the interior lamps come on.

Power for the interior comes from the orange wire (white are grounds) this orange is also power for the stop light switch, clock, dome lamp (coupe), rear compartment light, and front compartment interior lights.
all these items can work with car OFF and KEY out of the ignition.

Power for the fan is also an orange, but it connects from the heater switch there is a 14 brown that brings power to the heater switch from the ignition switch. your key has to be in acc or run for heater to work.

I believe there are 2 seperate problems here as I do not see a common thread for power to the two circuits unless something is really miss wired (which I am doubting), power from the fan is different than power for the tail lights.

The ONLY thing the horn relay is doing is providing a voltage point for the ammeter and suppling power to the horns when you ground the horn button (this closes the relay and allows power to go to horn). Nothing to do with lights.

Brake the problem into 2 parts, you can remove the power lead to the fan motor easy enough. see what happends with the rear lights, I suspect nothing will happen different.


The door interior light switch is easy enough to remove and clean, this should clear up the intermintent interior lamp issue.

As for rear lights, I think you have to look to the head light switch as this guy takes care of rear lamps (and interior if you rotate ****).

Hope I have helped here, maybe list anything else that does not work to help figure where things are going wrong.

Let us know,
Chuck

 

Chuck go pull your brake light fuse and then let us know if the courtsey lights come on... Just posting food for thought..... Dave..