C2: Headlamps blinking

[Kevin Brooks]

I have replaced all four headlamps on my '66 327/350hp 4-spd with Wagner non-halogenated lamps. The low-beam and hi-beam lamps are matching pairs. Here's the problem. I have noticed that after I switch from low-beam to hi-beam, within 5 min the headlamps start blinking. If I shut off the hi-beams the blinking goes away. The original owners manual does mention that this condition may happen and that to take the car to a service center for repair. What causes this and is this something that needs a service center technician to repair? I have checked the voltage coming off of my generator and voltage regulator - following the instructions given in the 1966 chassis service manual - and both check out OK. I cannot find any other wires that are shorting out and no other accessories are running when this occurs. All belts feel tight, connections tight, no corrosion visible on any terminals. Car S/N is 194676S106735, trim tag date code D15, body A-2122, STD trim. No power windows or AC. Alternator stamping is 1100693, 37 amp 12V, 4J9?.
Any suggestions? All comments taken serious and appreciated.

[Mike McKown]

Re: C2: Headlamps blinking

I think your headlight switch has an overload breaker in it. If it didn't act up before you replaced the bulbs, I would suspect the new ones are overloading the breaker.

[Jack H.]

Mike's correct....

HL switch has a built-in circuit breaker to protect against electrical circuit overload. The alternative would be to fuse the circuit, but in the event the fuse blew, you'd be on the road without lights! So, there is an internal circuit breaker in the HL switch itself to give protection as well as intermittent operation under branch circuit overload conditions.

You have basically two alternatives:

(1) Trace the wiring, find the circuit fault(s) and correct.

(2) Replace a worn/faulty HL switch.

Pro electrical shops would start by measuring the branch circuit current that flows when you turn the high beams on and compare that to the HL switch's circuit breaker 'trip' rating to initially assess whether the repair job is #1 or #2....

[Dave Suesz]

I've seen a lot of this...

There is probably nothing wrong with your car other than a bad headlight switch. Sometimes they start out weak, and get worse. The lows work OK, and the highs flash- this is the classic signal that your switch "ain't cuttin' it" any more.

[Ed Jennings]

Re: I've seen a lot of this...

Like all the otheres, I believe you have a bad headlight switch. In the highly unlikely event that a new switch doesn't cure the problem, then you possibly have an intermittent short in the high beam circuit.

[Joe C.]

Re: C2: Headlamps blinking

Kevin:

Did you or anybody else that you know, ever replace the headlight extension pigtails. If so, where did they come from?

Joe

[Don H.]

Re: C2: Headlamps blinking

Kevin,

I had a simalar problem coming home from Hershey. Turned out to be bad connections at the dimmer switch. Just another possibility. Don H.

[Kevin Brooks]

Re: C2: Headlamps blinking

Joe,

I personally have not replaced the pigtail extensions and have only had the car since '98, but given the appearance it would seem that someone had since it left the dealer's lot. I did, however, have to replace the headlight switch several years ago. I have not noticed any problems with the switch but I guess there could be an overload switch w/i it acting up.
Any recommendations for source of new/replacement HL switch?

[Joe C.]

Re: C2: Headlamps blinking

Kevin:

The reason that I mention the headlight extensions, is that I bought ALL my harnesses from Lectric Limited, EXCEPT the headlight extensions. L.L headlight extensions are correctly wired, mine were not. They were wired according to the Chevrolet issued wiring diagram, which is incorrect. I had to cross the wires in the left side connector before applying power to the circuit. The black, and black/green wires must be the same, right to left, not crossed as per the diagram. Lectric Limited fixed this problem, and correctly reproduces the extensions.

I buy most of my stuff from LICS, Dr. Rebuild, and Paragon. I don't know who to recommend buying a new switch from.

Joe