Pulsing Headlights
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Pulsing Headlights
I have a 1965 Ford F100 with a 1969 Mustang 302 V8. The headlights and dashlights seem to pulse when the truck is running. (Of course they do not pulse with the engine off.) Last night when I was driving it the headlights went off completely for a second or two and then came back on. This happened to me twice last night. I have changed out the alternator and voltage regulator.
Any suggestions would be greatly appreciated. I just acquired this truck and I'm trying to work my way through all the little problems that come with owning an older vehicle like this.
Any suggestions would be greatly appreciated. I just acquired this truck and I'm trying to work my way through all the little problems that come with owning an older vehicle like this.
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Joined: Jul 2003
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From: East Central Florida
Check your grounds. Battery to engine, Batt to body, Batt to chassis, Engine to body
Engine to chassis and Body to chassis. Some will be cables and some will be straps.
While you're at it if you have an FM radio, a hood to body ground ground strap acts as a supression ground to reduce ignition interference & noise in radio.
Over the years people delete or discard ground straps & wires. Time also takes its' toll with corosion & breakage. Also 60's tech was not as hi tech as 21st century is and some short falls exist in system harnesses. Usually upgrading ground system to make it contigious/ complete will rectify a lot of these common problems.
FBp
Engine to chassis and Body to chassis. Some will be cables and some will be straps.
While you're at it if you have an FM radio, a hood to body ground ground strap acts as a supression ground to reduce ignition interference & noise in radio.
Over the years people delete or discard ground straps & wires. Time also takes its' toll with corosion & breakage. Also 60's tech was not as hi tech as 21st century is and some short falls exist in system harnesses. Usually upgrading ground system to make it contigious/ complete will rectify a lot of these common problems.
FBp
Lead Driver
Joined: Aug 2003
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From: Boulder Creek, Ca
FBp is right on. I have same setup. Recently replaced wiring in 65 and subsequently found importance of good gound connections, solved few of my electrical problems. Purchased additional ground connectors and made sure surface clean and used diaelectric greace, particularly on the engine and taillight connectors. If you expect to be spending time on electrical circuit recommend wiring manual. Purchased mine thru Motorhaven and well worth the money.
Wonder if you found the problem in both low and high beam.
Wonder if you found the problem in both low and high beam.
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From: Colville, Washington
If happened after lights were on for a while, it could be the headlight switch circuit breaker. It is in the switch and is an auto reset type breaker which is why the lights came back on. To repair you must replace the headlight switch.(if that is the problem)
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From: N Richland Hills, TX
Article which originally appeared on FTE, first, years ago:
https://www.ford-trucks.com/article/...r_Brights.html
https://www.ford-trucks.com/article/...r_Brights.html
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Putt, Changed Headlight switch yesterday. Did not fix the problem. Too bad; that would've been an easy fix.
daveengelson, I just received a wiring manual I bought off of ebay. Can't imagine tackling electrical problems without it.
FBp, I believe you head the nail on the head. I will start reterminating all of my ground connections this evening.
Question to all. I just changed out the battery cables. The negative battery cable which connects to the engine block also has a smaller cable about 9 inches long with an inline butt splice connection on it. Do I splice into this and terminate it on the body or is this for some other use?
daveengelson, I just received a wiring manual I bought off of ebay. Can't imagine tackling electrical problems without it.
FBp, I believe you head the nail on the head. I will start reterminating all of my ground connections this evening.
Question to all. I just changed out the battery cables. The negative battery cable which connects to the engine block also has a smaller cable about 9 inches long with an inline butt splice connection on it. Do I splice into this and terminate it on the body or is this for some other use?
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Shakespearesdad,
I believe I may end up doing the fix you suggested with the relays. Thanks for the information on what is needed and how to connect it all.
I believe I may end up doing the fix you suggested with the relays. Thanks for the information on what is needed and how to connect it all.
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From: Upstate NY
You shouldn't have to do anything with the extra ground wire coming off the terminal. That is for any optional equipment that might be added. My ground strap was bad where it connected the back of the intake manifold to the firewall. But, as already stated, they all need to be sound!
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From: Sun River St. George
If you are using one of the older mechanical voltage regulators the lights will pulse. Annoying but not a show stopper. If you have installed the newer halogen headlight bulbs the extra amperage these lights draw will trip the circuit breaker in the light switch. A solid state voltage regulator and relays in the headlight circuit will solve both these problems.
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Problem Fixed
Well I found and fixed my problem with the pulsing headlights (...and instrument cluster lights.) With your help I felt that probably the grounds weren't making good contact and that the problem would most likely be found in the charging system. I started by following the leads from the alternator to the voltage regulator.
What I found was the FLD lead from the alternator to the voltage regulator had been spliced twice inside the wire loom and as I was pulling these wires it very easier pulled out of the inline butt splice. It was most likely arcing inside the butt splice causing the pulsing or flickering condition. The STAT lead had as many splices too so I completely rewired them from the VR to the ALT.
No more pulsing/flickering lights.
I will continue on with my regrounding the entire truck. It couldn't help but make things even better.
Thank you all very much for your help!
What I found was the FLD lead from the alternator to the voltage regulator had been spliced twice inside the wire loom and as I was pulling these wires it very easier pulled out of the inline butt splice. It was most likely arcing inside the butt splice causing the pulsing or flickering condition. The STAT lead had as many splices too so I completely rewired them from the VR to the ALT.
No more pulsing/flickering lights.
I will continue on with my regrounding the entire truck. It couldn't help but make things even better.
Thank you all very much for your help!
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