Headlights flicker on my 1988 Ford F-150 Pickup Truck.?

Question

With the truck NOT running all light (Headlamps, dash lamps, etc) are steady lit and not flickering.
With the truck RUNNING all light (Headlamps, dash lamps, etc) are flickering.
I have replaced the Alternator twice, did not fix the problem.
I have replaced the Ground battery cable with a new one.
I have cleaned the battery post and cables.
I have replaced the battery cable ends with new ones.
What is causing this problem, help?

More detailes: ALL LIGHTS flicker when it is running.

Answer 1

Bad ground.Usually attached to the block.Replace cable or sand and clean it.

Answer 2

This is a problem with Fords from 1987 to 1992, and the most common reason for this is the electronic ignition. The best way to diagnose and fix the problem is to take the vehicle to an automotive electrical shop, where they will put the vehicle on the scope and track down the problem. Otherwise, as you found out, you are just chasing symptoms without finding the problem, and wasting a bunch of time and money.

Answer 3

the reason and fix depends on if you have a internal voltage regulator or an external voltage regulator to control alternator output. 1988 Ford trucks had either one depending on production date
try this, Does the Alternator have a connector at the back? if so it more then likely has an internal regulator.
Unplug this connector, start your truck up, turn on your headlights. Do they still flicker ? No
regulator is defective.
Still flickers. Check Grounds

Answer 4

Try to find which lamps are causing flickering.
Then, check the wiring, cause you have a short circuit in it.

Answer 5

sounds like a loose connection. try and follow the wires for the lights that are blinking and look for an splices or loose connections

Answer 6

ground wire coming from headlight assembly to the radiator support area bad, loose, or corroded connection