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Good evening. I have a 1978 Ranger Lariat. Recently, the headlights started flickering, and the gauge lights went out, and the radio doesnt dim as it should when the light are on. I had the battery checked and it was fine. I thought the positive battery cable was a bit frayed, so I replaced it. I was wondering if replacing the negative one as well would help. Another problem that happened is that the truck would not start. I would turn the key, then nothing - no lights or anything. If I took the positive post off the battery and put it back on, the lights would come back on, then it wouldn't start. When I replaced the positive cable, it starts fine now, but I still have the flickering in the headlights,, gauge lights, and the radio doesn't dim? Any ideas? I'm hoping its an easy fix - it seems like something is loose somewhere but I don't know where to start. Any help would be appreciated. Thanks!
When you replace the positive cable did you clean the other wires connected to starter solenoid? Did you use a backup wrench tightening them up? Is the radio a stock Ford radio? It does sound like you have a grounding issue. Ground to engine block, engine block to body, cab strap to frame rear lamps to frame. Gauges and lamps grounded behind instrument cluster on column dash support. Dimmer switch can cause lamps to flicker but would have no effect on dash illumination. Grounds seem to be the bane of older vehicles, whatever is using the power needs a return path to the battery. Grounds are just as important as the power feed. Use an ohm meter to check all of your grounds to battery, get an extension lead and take it right off the ground battery post to your headlamp ground or whatever is giving problems.
X2 on replace the headlight switch if random instrument lights are dimming on there own. Then you might check each instrument cluster bulb for a good connection. I am pretty sure the radio face/dial itself does NOT dim. Check the main elec connector where the instrument cluster elec connection connects to the back side of the instrument cluster. X110 on clean all grounds and add one.
X2 on replace the headlight switch if random instrument lights are dimming on there own. Then you might check each instrument cluster bulb for a good connection. I am pretty sure the radio face/dial itself does NOT dim. Check the main elec connector where the instrument cluster elec connection connects to the back side of the instrument cluster. X110 on clean all grounds and add one.
I agree with all of this. I had the same issue and replace the dimmer switch, cleaned grounds and also the floor switch. All were cheap to replace and told my self the might as well. The only lights I currently don't have is are back ups. Its not the neutral safety switch but I really don't care about it at the moment.
The headlight switch has a built in circuit breaker. When it over loads it makes the headlights flicker. A positive wire that is grounded anywhere in the circuit will cause an over load and the headlights will flicker.
For example, if a parking light hot wire was grounding in the socket.
Look for hot wire touching body or frame or pinched. This can drain the battery too.
X2 on the floor dimmer switch can cause problems when they go bad.
All the headlight power goes through the floor dimmer as well as the light switch.
Keep looking and you'll find it.
Good luck
The only lights I currently don't have is are back ups.
The backup lights were the last thing I thought would work when I bought my truck, well one of them did work.
I put new tail light assemblies in because the original ones were cracked and faded and I did replace one backup light bulb socket
so now both backup lights work.
The rheostat in the headlight switch was junk so I replaced that switch too.
Now the dash lights work but all it has is the gas gauge and temp gauge
and they are dim and the plastic lens is scratched so
basically the instrument cluster sucks.
Door jam light switches took some work to get working too.
I still need to replace the turn signal switch because they don't cancel.
I will replace the wiper motor switch when I change it over to intermittent wipers.
The ignition switch is good.
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