Electrical Issues

[Dominic]

Hi all, I'm having some electrical issues on a 68 RR. Currently, the things not working are:

• Turn signals don't work (but flashers/headlights/brake lights all work fine)
• Gas gauge
• Blower motor
• Wipers

We just took out the dash gauge cluster to try and clean some electrical points, but are there other things to check while cluster is out? I'm sure there could possibly be bad ground(s) somewhere. Where are the locations of these grounds that could be causing these problems?

Any tips before we try and plug the gauges back in would be greatly appreciated! Thanks.

 

[69L48Z27]

If you have the cluster out, check everything. Grounds are part of the assembly. There are very few actual grounds that are loop terminals with screw holding them to the body.

- I don't follow your turn signal problem. Flashers you mean 4 ways? Sounds like I would be looking at the switch.
- Gas gauge. Lots of threads here describing process to troubleshoot. Make sure the sending unit is getting ground. Short out sending unit wire to see if guage reacts. Go from there.
- Blower motor. Single wire down on your heater box. Start checking input voltage from fan switch at that location. Work towards motor or switch from there. Use a multi-meter.
- Wipers. Not real good with these but check wire diagram and check voltages/grounds.

 

[Frank Mopar]

Get a Power Probe. Best tool you can have to trace these issues down.

 

[Coronutcase]

I had all these same issues when I bought my 67.

On your turn signals if your 4 way emergency flashers work, try swapping the flashers under the dash (if you haven't already). If so then someting's most likely wrong in your steering column, maybe the actual switch that your lever connects to.

Gas gauge can be a nightmare! Could be the gauge, could be the instument cluster circuit board, could be the sending unit or a ground. Try what 69L48z27 said by pulling the wire off your sending unit, stick a wire inside the plug and touch the other end to a good ground. Have someone else watch the gauge, it should go all the way past full and then back below empty when you remove the ground wire. This will let you know if your gauge is working. You can pull the sending unit out of the tank and bench test it with an ohm-meter.

The blower motor on mine turned out to be the switch itself, may not be the case with yours.

The wipers did not work at all on mine. Turned out that the motor was just locked up from rust on the shaft. I took my motor apart, cleaned all the rust, greased it good and put it back together. They work fine now. Did some sandblasting and painting while I had it apart too:

Good Luck!

 

[PurpleBeeper]

Good advice above & I'm repeating some of that here.
1. Turn signals - there are TWO flashers, one for turn signals & one for "4-way emergency flashers". If the emergency flashers work, then you've determined the bulbs are all good already. If the dash turn signal lights come on, then it's most likely the flasher itself (swap with good emergency flasher to test) or the turn signal switch in the column (check with electric meter vs. the wiring diagram at one of the two plugs at the bottom of the steering column...the smaller one I think).
2. Gas gauge - could be sender inside gas tank, gauge itself, the dash cluster circuit board or the wiring going between the sender & the dash cluster. Usually, the first step (with dash installed) is to ground the wire at the sender with the key on & the gauge should go all the way full...but you have the dash out already. You could check continuity from the sender to the wire at the dash (green?). REMEMBER the dash only takes 5 volts (voltage limiter in dash), so don't use a 12 volt source. I'm not sure how to check the gauge with the dash out? If it's bad, the dash would have to come out a 2nd time. ANYONE KNOW HOW?
3. Blower Motor - just run 12 volts + ground to it & see if it turns on. If yes, then it's the switch or possibly wiring that's the problem. Blower motors commonly burn out.
4. Wipers - have their own wiring harness (top plug on bulkhead disconnect) with 4 wires (at least on 3spd wipers). Check vs. wiring diagram & run 12 volts to appropriate wire(s) from under the hood to see if it moves. Also check the ground which should be a little metal strap on one of the wiper motor bolts which grounds to the body. If that all checks out, then it's most likely the wiper switch OR a connection at the bulkhead disconnect.
Everyone, please feel free to jump in & correct me or add more info.
Hope This Helps

One more thing, it's not all that common of a problem, but you could check the 8-prong(?) plug behind the driver's kick panel which has wires for the back half of the car (turn signals, emergency flashers, gas gauge, etc.) which you could check for corrosion or bad connections.

 

[Dominic]

Thanks for the suggestions everyone! Really appreciate it.

After some work today, we cleaned the gauge cluster/contact points on back, but still have a few issues.

• We tested the gas gauge, with 5v battery, and turns out it was not working. So luckily, we had a spare cluster that had a definite working gas gauge(also tested with 5v battery outside car) that we then plugged into the dash. BUT, still not reading anything in key-on position & after we grounded the sending wire!! Not sure where issue is. Possibly wire going from sender to cluster?
• Turn signals are acting funny. When using 4 way emergency flashers, everything works fine. All 4 lights come on and flash with no problems. But with turn signal(even with new flasher unit), still not working as it should be.--- In bottom/left turn position, only front left indicator light brightens, but NO pulse! Nothing else happens on any other positions... Could this be faulty turn signal switch? Bad ground?

Thanks for the tips !!
We have yet to check wipers and blower motor ...

 

[69L48Z27]

For you gas guage, find the wire up in the kick panel and ground it there and/or check continuity to the rear. That will rule out the rear part of the harness.

No advice for you with turn signals. Almost sounds like a bulb is missing in the circuit. But I'm sure you already covered all that.

 

[Dominic]

Good news! After a lot of monkeying around with the electrical issues, we finally found the big problem.
It turns out there was an empty spade terminal on the back of the fuse box... We found a loose power wire w/ connector hanging, and we didn't know what it was for until we found the empty terminal. Connected them together and boom! All works now. I guess after sitting for 20 years it apparently came out ?? Oh well.

But anyways, that fixed all the listed symptoms. Blower motor, gas gauge, turn signals, reverse lights, wipers, all working great!
Thanks everyone for the great helpful tips, we really appreciate the advice!