C2 Insturment Panel lights

[Garry E.]

I was driving my '64 roadster last evening at ~60mph, head lights on, and I noticed the insturment panel lights suddenly growing brighter and brighter until the insturments were well illuminated and easy to read. However, after a few seconds of this, they started to grow dim and faint again. This cycle continued during the entire drive of ~ 30 minutes.

I don't drive the car that much at night so the insturment panel lights are rarely used. However, what I saw last night doesn't appear "normal".

The alternator is orignal and has never been re-built. The voltage regulator has been replaced at some time (?) in the past.

Any thoughts on what might be causing this problem.....?

Garry #38705

[Jack H.]

Re: C2 Insturment Panel lights

Two causes that I can think of...

(1) The dash lamps are controlled by a rheostat that's built into the headlight switch. Either that portion of the switch is loose and drifting in position or the rheostat's contact surface is oxidized and you're randomly changing the resistance value of the dimmer function.

(2) The charging system is ramping battery voltage up/down with the dash lamps reacting in lockstep. But, if this is the case, you ought to see your ammeter needle moving in sympathy and a voltmeter across the battery confirming the change in battery voltage....

[Garry E.]

Re: C2 Insturment Panel lights

Jack....

The ammeter appeared to hold constant throughout these cycles......

You have a good point regarding the headlight switch..... It might be worth changing given that it is original, as well.....

thanks......

Garry

[Albert P.]

Re: C2 Insturment Panel lights

Probably not necessary to change the switch; just operate the rheostat from fully ccw to fully cw many times to remove the possible oxidation.