Electrical help

[edison1970]

I have a number of electrical issues I have been chipping away at but I'm stumped on a few.  Headlights didn't work which I traced to a bad headlight dimmer swtch. Now that I got the headlights working, the rear tailights stop working as soon as the headlights come on.

Next oil pressure and temp guage not working.

No tach.

No dash lights.

Only high speed on blower motor.

This electrical stuff is time consuming.

[Cuda Cody]

Is it a fresh paint job?  Start by checking if the ground are good.

[Ed]

What Cody said.   I had lots of issues after I did rotiseree repaint on a car.   It was all ground issues because everything had paint on it.

[JonH]

Edison....electrical issues? WTH

[1 Wild R/T]

Edison....electrical issues? WTH

[edison1970]

I ran a ground wire from the battery to the trunk and still nothing. Any ideas where to look next? Test the light switch maybe? I loose all power to the reverse lights and plate light when the headlights are on.

[Chryco Psycho]

Do you you have power from the headlight switch to the taillights at the headlight switch
the resister pack for the blower motor has probably failed , it is in the heater box
the 5 v power supply for the gauges has probably failed as well or is missing

[edison1970]

I'm going to tackle one issue ata time. I figured I would fix the tail light issue first. As I said before, tail lights work. As soon as I flip the switch to head lightsl the tail lights loose power. I ran a ground from the battery to the tail lights and still nothing. So then I checked the connection from the dash harness to the trunk harness. Cleaned the connections even though they looked good and coated with dielectric grease. Still the same. SoI think the next step is the switxh in the dash. This is where I need the help. I attached the diagram from the manual. I hooked one end of my test light to the center connector which is where 2 black wires come in, the other end tothe pink and it lights in the 1st click of the switch. That must be parking lights.Then when I move the switch to head lights, it turns off. Am I testing it wrong or is the switch just bad?

[Chryco Psycho]

light green should be the park lights so you can test that terminal on the switch & see if it switches power off when the headlights turn on , if it does the problem is inside the switch .

[edison1970]

Made some progress tonight. The headlight switch ended up being bad. I was lucky to have another to replace. Now to the dash lights. Correct me if I'm wrong, I should start at the dimmer switch. It should be powered from the headlight switch.

[Chryco Psycho]

true the power comes from the headlight switch through the dimmer switch [often bad] & into the orange circuit that feeds all the interior lights , dash , radio , shifter etc

[edison1970]

Kind of bummed. I fixed all of the lights. Bad dimmer was the dash light culprit. Replaced with a spare I had. My final hurdle inside is the temp, oil pressure and tach. Tested temp gauge with 3 AA batteries and it worked. Test the wire from the gauge to the sending unit and is good. Now I assume the sending unit is bad even though it is brand new. Should be an easy fix. Now the bad. Tested the oil pressure gauge and it's dead. Should I just buy a replacement from Classic Ind. or have the original repaired? They are $80 but don't know how good they are. Also how about the tachs they sell. Any good?

[dodj]

Don't know about the quality of Classic's repro tachs but you can rebuild your own with a kit from rte.