Odd Interior/Tail Light Issue

[jhdeval]

The other day I did the single to dual master cylinder upgrade. While I was disconnecting the brake pedal I saw a few sparks I assumed I had grounded the brake switch. I hit it one more time after that. Now I have no instrument lights or tail lights and oddly enough my interior lights glow when I turn the headlights on. They are not full bright but probably 70%. I pulled the taillight fuse an replaced it but that did nothing for the headlight/interior glow. Any idea what and where I need to look?

 

[jhdeval]

Last night I went through the wiring diagrams in the service manual and it does not show the brake light switch. Best I can come up with is maybe I blew the ignition switch? Possibly the headlight switch. Any suggestions at all?

 

[TrailBeast]

Partial random lamp brightness is almost ALWAYS a ground issue.
I'd also say there is a darn good chance it could be one of the plug in connectors lost it's connection.
Try turning on your headlights so the interior lights are glowing and wiggle test all those connectors to see if you find it.

 

[67Dart273]

Recheck for power at the tail light fuse, and after you get power there, check for power at the inst fuse WITH THE light switch turned to park or head. Check power at the tail fuse with the light switch in park, so that it puts a load on the circuit.

The inst. lamps are fed from the tail fuse, through the dash dimmer, through the inst. fuse, (tan) and to the dash lamps (orange.)

I think what you'll find is that you are not getting power through the tail light circuit to the headlight switch. The pink supplying the dome circuit comes off that terminal, so if it's getting "very low" power it may power the dome lights very dimly, as you probably have either a door open, or the dash dimmer twisted to "dome."

Realize that the headlights and only the headlights get power off the ammeter circuit

 

[norshorblufish]

I agree with 67Dart273.
Also do you have brake and signal lights. I believe the brake circuit also goes through the signal switch. Correct me if I'm wrong.

You learned an important lesson when working on anything electrical especially with constant power as the brake switch does disconnect the battery.
It's a bugger tracking down what shorted out.
Believe me it's easy enough to forget too.

 

[jhdeval]

I double checked the fuse and I swear when I looked last night it looked good but today it was definitely burnt. I replaced it and it fixed the taillights. This morning I turned the headlights on and I did not see the interior lights glow so hopefully replacing the fuse fixed it. I will know later.