i have a 78 f100 that i gave to my son. he just replaced the head light switch for flickering problem. the flickering is gone and now so is the instrument lighting.
when i turn on the dome light it starts to flicker and i can hear a clicking noise under the dash. anybody got any ideas as where to start or have good readable wiring diagram that might be willing to send me. thanks

 

I'd pull the instrament cluster out, make sure that the wires going into it arent cut, then I'd make sure that plastic thing on the back of the cluster with all the copper lines running through it isn't burnt out. I had to replace mine with a junk yard special. I used to have the flicker problem and replaced my headlight switch and everything worked after that. Maybe you got a faulty one.

 

Welcome to the FTE site

Sounds like you need clean up all the grounds in the lighting system.
Plus,where the voltage regulator mounts.

The "type" of headlight and cluster lighting flickering is can be caused by a couple of things.

The Voltage regulator and the condition of being mounted can be the cause of flickering like you describe.
Clean up the grounding area and coat with di-electric grease to prevent further corrsion and problems.
Check and clean, ....then secure all grounding spots.


There is a also another type of headlight flickering that is caused by the built-in Circuit breakers in the headlight switch.

This is Ford's bad design and a lot of people opt for the "Relay Type" system that can be done.
Doing this takes the load off the circuit breaker and instead routes the power direct from the Battery.
Result: No more flickering headlights

You can read about it here.
https://www.ford-trucks.com/article/...r_Brights.html


BTW, just because you buy a NEW part... doesn't mean it's going to be good.

You should also clean up around the floor dimmer switch.
They are known to cause problems as well from moisture & corrosion.


Belldog said: then I'd make sure that plastic thing on the back of the cluster with all the copper lines running through it isn't burnt out.

That part is called a "Printed Circuit"

 

Don't forget you could take your panel out and plug your lights in with out installing it so you can have access and see if your connections are good.

 

thanks guy for your help . found the problem my son had a bad ground on the radio he installed . and we found that the new headlight switch was bad from stock. reinstalled the original switch and found a solid ground for the radio and every thing works normal . thanks again

 

I have the same problem but on my case the tail light stop working and the side ligths too . the stop ligth still work but the rest doesn't wath can I do.