Faulty Ground?

[Stormer]

Headlights dim with blinkers or brakes. Rear blinkers are fine with headlights off but the opposite side dims while the other one flashes with headlights on.

Where should I start?

 

[Big_John]

Bad ground for sure... I'd start with the headlight grounds.

 

[65sporty]

I agree with big john, start checking grounds you might as well ck all the grounds on all the lights

 

[thrashingcows]

And make sure you have good grounds from battery to body, and from motor to chassis and body. Can never have too many good grounds. Even grounding the taillight housing to the body is never a bad idea either.

Installing headlight relays will help with teh dim headlights. Taking the load off the OEM switch, and having the relays directing the power to the headlights is a great idea too.

I'll be doing this upgrade soon on my 84 Cummins W350 crewcab, and the wagon.

 

[67Monaco]

Anybody have a list of all the grounds? FSM lists them but locations aren't exactly clear.

In a related note, bypassing the ammeter helped me.

Then again I also just removed the factory fuse block and went with two aftermarket blocks. The reason is long and drawn out but let's say I didn't think it safe to reconnect the battery after finding the "fixes" done on the original wiring behind the fuse block. So now we have room for future expansion and modern ATC fuses.

 

[BJS racing]

I agree. I would also make sure that the alternator has a good ground on it as well as the regulator. That may be making the charging system weaker.

 

[thrashingcows]

I agree. I would also make sure that the alternator has a good ground on it as well as the regulator. That may be making the charging system weaker.

Very good advice...I had forget that one. ;)

 

[68Bigred]

Make sure the ground strap from the engine to the firewall is good. After I painted the engine bay I had similar issues but I found mine to be the drivers side ground in the headlight harness. Best to check them all really!