1979 F100. Headlights pulsate with the engine rpms. When idiling they are less bright than when I am crusing down the road. I replaced the headlight switch but it didn't help. The dash lights pulsate as well. And when the headlights are on, the oil pressure guage and the temp guage read much higher than with them off.

I am pretty sure it is a wiring issue, but I have no idea where to start looking.

 

Start with cleaning the wiring contacts & grounding surface/mounting area of the Voltage regulator.

If that doesn't sure the problem do a complete retro-fit of headlight relays which is covered in the tech articles called : Whiter whites & Brighter Brights

 

Yea, what Mil1ion said. In fact, I fixed this problem once just be changing out the regulator.

 

I just replaced mine, was doing almost the same thing, then the engine started to miss? once I changed it I have no problems since.

 

It the process of elimination when trying to find the "Headlights pulsate with the engine rpms" , I've encountered where it was the voltage regulator, and time where it was the alternator.

When the lights start flashing, put your hand on the the headlight switch and check if the switch is getting hot, this is a sign of a switch going bad.

 

If it's the origional voltage regulator or a older style points type then your headlights may pulsate, If you buy a new voltage regulator it should be the electronic type, they wont pulsate any more. They are about $13 at autozone.

 

Went and bought a voltage regulator. Got ready to put it on and noticed that the bolt that the ground is attached to was loose. Tightened it up and now the headlights are fine.

Still have problems with my guages reading off when I turn on the headlights though. i am going to try replacing the cluster tonight and see if it makes a difference.

Thanks alot guys.

 

Still have problems with my guages reading off

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Please explain specifically what you mean by this statement ?

My Guess,
You don't think the gauges are reading the proper value of what they should ?

There are ALL SORTS of reasons why this could be.

 

Friend of mine had a problem with his gauges being off when the headlights came on. Turned out to be a ground problem with the gauge lights.

 

Gauges don't have lights.

I think you meant the Cluster lighting ?

 

What are the little bulbs on the back of the cluster? Little plastic lamp holder, twist lock

 

Those are Cluster Illumination bulbs ?

http://www.clubfte.com/users/mil1ion...erBackView.JPG




Aftermarket style gauges have light in them to illuminate them

 

I had meant the cluster lighting. There is a braided flat cable for a ground on his insturment cluster, and when he clean up the ground and reattached it his gauges started reading on.

 

Let me clarify

Normal daytime driving, my temp guage reads between the "o" and the "r" on Normal.

Turn on the lights and the guage works its way up to between the "l" and the line at the far end of the guage. The Oil pressure Guage moves similar to this. The Fuel level and Ammeter guages don't change at all.

If you turn off the lights, the guages return to the normal ranges.

Any Ideas?

 

Sounds to me like power loss to the ICVR (Instrument Cluster Voltage Regulator) on the cluster.They don't last forever.

Here's an illustration that shows is.

Here they call it the IVR and is located just to the right of the word SPEEDOMETER.



NOTE: Don't always go by Ford gauges as functioning properly.

They have been an ongoing concern for FORD owners.

Maybe clean the grounds and check the ICVR for corerct curent pulse & voltage output (5v)