71 Project, No Dash Lights

[Redliner]

I'm close to firing up a 71 project that's been two years in the making. I'm currently testing the electronics and I have about 50% that works. Here's where she stands:

1) No Dash Lights. I have continuity through the fuse. How is the printed circuit board grounded?

2) Nothing happens when the headlight switch is turned on. It could be the 52 year old original switch. I'm sure it's grounded.

3) Turn signals work fine except the indicator lights in the dash (see # 1 above)

4) And the brake lights, dome light, radio, blower,..all work fine.

Before I get my multi-meter out, remove the dash bezel and get to the gauge carrier and printed circuit (fun) any suggestions?

Thanks in advance,
Redliner

 

[grzewnicki]

1. Circuit board is grounded through black wire on the instrument panel connector, all the following items are grounded through this wire: inst panel lights, turn signal indicators, hi beam and fuel gauge. If none of those are working then possible that the ground circuit in the circuit board is bad. To verify pull dash connector and check the black wire has continuity to ground, it ties into ground circuit for cig lighter, headlight switch, wiper switch, radio and heater control panel light. I believe it is the black wire that it connected to sheet metal dash support (wire ending in a ring terminal) behind the dash and above the heater control panel, close to where the flasher unit sits in its little spring clip holder.

2. Gotta take this step by step, while you have dash connector apart check the grey wire for power, that comes from the inst lamp fuse, can also check it here easier: pull bulb out of heater control panel, using a test light check for power there. The grey wire from the inst panel fuse feeds: radio illumination, heater control panel light, inst lights, the headlight switch is its path to ground through a variable resistor (contact on the resistor can get corrosion on it and stop the lamps from working, it is easy to see the contact and resistor part when you have the headlight switch out).

 

[Redliner]

GRZ,..thanks for the input. Very useful. Today I took the dash bezel out and did some preliminary testing. The entire right side of my fuse box is dead. The left half is alive and well. What could be the commonality?

And tomorrow I'll get to work with my test light and run the traps as you're suggested.

By 'resistor' I assume you mean the the resister that's a part of the headlight switch.

Also, on my 71, where is the 'fuse-able link'? My research indicates that could be a source of my aggravation.

Thanks again GRZ,..
Wes

 

[Twisted_Metal]

There is more than one fusible link.

The first one is between the battery and junction block at the front of the car.

There's also one at the voltage regulator and another near the firewall connection.
Both of those are 20 Ga orange if they are factory.
(according to my Haynes manual)

 

[Redliner]

Thanks,..I'll run some continuity tests on the red wires in the engine bay,..make sure that the linked thinner orange wires are ok.

Thanks again!

 

[Redliner]

Hey GRZ (or anyone else). After numerous continuity tests today, the problem commonality is the 'instrument wiring harness'. (This is the wiring that goes through the connector block mounted to the firewall near the accelerator pedal). Nothing that's connected to this harness works,..headlights, wiper switch, lighter, cluster illumination, etc.

I detached the connector block halves and the female half is dead.

And again, the right half of my fuse box is dead.

Any ideas on the fix?

Thanks again!