70 Challenger Wiring Issues - Wiper Motor & Dome Light

[TOP1PERFORMER]

I did a quick restoration on a 1970 Challenger, base model hard top, standard dash, 2 speed wiper, that I recently purchased. Did the body, interior and some drive train. I'm getting close to finishing but didn't realize there were some electrical issues. I was able to find some wiring diagrams but can't trace the problem. I'm at my wits end. Thought someone could help.

With everything plugged in, the dome light works when I open the door. It does not work when I rotate the dimmer switch counterclockwise. With ignition on, the wiper motor does not function in either of the 2 positions. With the ignition on and the wiper switch on, the wiper motor works in low and high speed when I rotate the dimmer switch counterclockwise to the dome light position. Again, the dome light does not light up using the dimmer switch. It seems to be powering the wiper motor.

I could see the previous owner was under the dash with an aftermarket radio. Not sure what else he might have done. Maybe its nothing he did but I just can't find the problem.

Can anyone offer some suggestions?

Thanks,

Fred

[Cuda Cody]

Welcome to the forum @TOP1PERFORMER      Really cool car!

Sounds like a bad ground or short.  A couple questions?

Is the wiring factory?

Did it work before you replaced the interior?

What color are the wires to the dome light switch?

Have you tried unplugging one switch and seeing how the other one works?

[TOP1PERFORMER]

Thank Cody. Glad to be part of it again. Always been a Mopar guy. Mostly e-body.

Wiring is all factory original.
The car was in very rough shape so I never tested much of the electrical. Bulb was missing from the dome and never tried the wipers. It went under cover as soon as I got it.
Colors to the Dome switch - please see pics
The Dome light does not go on using the Dimmer Switch in any scenario. Only when I open the door. The wiper motor does not go on unless the dimmer switch is plugged in and rotated fully counterclockwise to the dome light on position.

[TOP1PERFORMER]

...The wiper motor does not go on unless the dimmer switch is plugged in and rotated fully counterclockwise to the dome light on position.
...with the ignition on.

[Slotts]

You will need to reverse two wires on the two connectors going to the wiper switch. It is currently wired for a variable speed setup. Make sure the battery is disconnected while doing this. Swap the brown w/ white stripe and the red wire. A slot jewelers screwdriver fitted into the front of each connector to press down on the barb that keeps the wire from coming out of the back (wire side) of the sockets. Once the two wires have been removed, use your screwdriver to lift the now pressed down barb so it will lock again. The brown w/ white strip is now into the two position socket and the red is now into the four position socket. Reconnect the battery, turn the ignition on and see what happens.

The dash dimmer switch is a two circuit device. One circuit if for reducing the voltage feeding the dash lights and the second circuit is to enable a ground closure to to turn the dome light on. 12 volts battery power is always present at the dome light. It is either when either of the door switch open or the dash dimmer switch is turned fully counter clockwise after the click.

Jim

[TOP1PERFORMER]

Jim,

Thanks. I'm going to head out and give it a try.

Fred

[TOP1PERFORMER]

NG. Reversing the Red and Brown w/White Strip just reversed the high and low speed position.
Nothing else changed.

What I didn't notice before and is happening regardless if the wires are reversed is that when the door switch is open with the dome light on, the wiper motor runs in both positions with the dimmer switch clicked all the way counterclockwise. When I close the door dome goes out and motor stops.
Is the dome circuit tied in with the wiper? Wires crossed somewhere else?

[Slotts]

Ok, when you said the high and low speeds changed, is the current wiring operating correctly? Park, Slow, Fast, where previously you had Park, Fast, Slow?

With other areas to possibly needing looked into, let's first make sure you have a good ground between the switch panel and the dash frame. If you are currently testing without the switch panel screwed down with all four mounting screws, the switch panel can be grounded by simply connecting an alligator clip type test wire. One clip on the metal switch frame and the other side to a clean bare metal area on the dash frame. A clean screw head, bolt, etc.

Let me know what is happening with the switch panel grounding and the current wiper speed movement. One at a time...

Jim

[TOP1PERFORMER]

 
Jim,

When you get tired you miss the simplest things. I feel like an idiot. It was the ground. The wiper motor speed control works at Park, Slow, Fast at the original plug wiring before we reversed them.
The Dome light works with the door open and with the Dimmer Switch at full clockwise position.

This all started when I had to remove the headlight switch. The contacts were not making good connection so I took the switch apart and cleaned them up. That was when I tested the wiper motor...with the panel removed from ground.

A big thank you for your help.

I do have 1 other question while I have you:

There is a spliced wire off the fused link from the started solenoid and connected to a black wire which apparently is running through a drilled hole in the main firewall harness connected with a wire nut under the dash to another harness...real craftsmanship. See PICs. I think the red wire may have broken off from the bottom center plug because I found a very small piece of a male connector inside the plug. Can only assume. The 2nd pic has 2 arrows. 1 arrow shows the black wire and the 2nd arrow is pointing to an open port on the lower plug where it may have gone. Don't have a clue then where the red wire under the dash would connect to. Any thoughts?

Fred

[Slotts]

Hey Fred,
I noticed that you are also on East Coast time from your avatar info. I started at 6:00 am and yes, there is an ability to have too much Mopar fun in one day. 

I would be glad to help you with a little bit easier way of troubleshooting these issues. If you could click on my website below, it will show my email address. Could you let me know when we could look into a time where you can be with the car, phone and meter for testing?

Will check this thread tomorrow morning and see how you made out so far. It's time for me to go choke down some food and catch some ZZZ's.

Jim

[TOP1PERFORMER]

...clarification: Under the hood, the blue wire with fusable link connected to the red wire and spliced to the black. That goes through the firewall and connected with the wire nut to the red wire under the dash.

[TOP1PERFORMER]

Jim,

I fully understand. My timetable is very similar to yours. Enjoy your night and catch up with you tomorrow.

Thanks again,

Fred

[Cuda Cody]

Fusible link to red wire...  To bulkhead fuse.  Looks like someone bypassed the bulkhead fuse.  Were they trying to fix the bad ground?

Click photos to enlarge

[anlauto]

I was driving in the States the other day and saw a road sign I thought was odd....It said "headlights must be on when using wipers" maybe in your case it means you need to have the dome light on when using wipers ? 




Just kidding....funny how a ground can really mess with things...

[Chryco Psycho]

it is very common to have the connection through the bulkhead corrode & get hot from resistance & melt the plug , typical problem so they bypassed the bulkhead & ran the wire inside to power the car
Welcome to the site from Panama Fred