Turn signal quandary
 

New to me 1978 C10

I had various lights out on all corners, so I went through and replaced all the blinkers, running, brake and backup lights. I also went though all the grounds, cleaned and dielectric greased them all. I also yanked the blinker relay and cleaned the blades and dielectric greased it.

So at this point everything works as it should, except the blinkers.


They work fine when the headlights are not on.

When I turn the headlights on, the blinks are sporadic (side markers blink opposite of the front running lights and are dim).

Now here is where I'm at a loss....

If I start the car and rev it up everything works as it should (blinkers work as normal).

At idle the alternator is putting out 13.4 to 13.3. When rev'd up, it's puts out 14.5 (this does not change when the headlights are on or off).

Now I had the battery down to 80% (according to my "smart" battery charger) as I had the lights on and off most of the evening while trouble shooting grounds and such.

SO....

Will a battery at 80% make the turn signals act like this?

Is the blinker relay temperamental to a low voltage situation?

I appreciate the help, as this is an oddity to me.

singleshot

Re: Turn signal quandary
 

Side markers normally blink opposite of the front blinker lights when the headlights are on. When you turn on the headlights it draws significant power and the voltage drops even more than you thought it was if you didn't measure with a multimeter. I would say you are observing nothing alarming, just run the truck and charge up your battery, and you should be good to go.

Re: Turn signal quandary
 

I would try a new flasher. "blinker relay". They often are sensitive to low voltage. They are inexpensive.
George

Re: Turn signal quandary
 

Turns out it was the relay.

Whether or not it was bad is debatable, it was evidently a replacement for the original for the trailer brake set-up which consisted of a huge heavy duty relay. The entire trailer brake system at some time or other was disconnected.

So rather than reconnecting it (which I will probably never use), I took the suggestion and picked up a new HD relay from Napa.

Night and day..

Thanks for the suggestion...

On to the next bug, the starter :banghead:

That will be a whole different thread if the replacement does the same crap this one is doing.