Lights FLickering....

[Hunter4x4]

Quick question... . after sitting in sub-freezing (and some sub-zero!!) weather for a week or so, I fired the beast up and all of a sudden my lights are flickering, in a a faint, rapid manner. Thought it may have been cold related, but after driving her for about an hour or so this morning it didn't seem to go away. As the engine speeds up it seems to go away, but I thinks it's speed sensitive, i. e. , as engine RPM goes up the flickering speed up and hence becomes less apparent.



Any suggestions or ideas?



Thanks in advance!!!



Mike

 

[DavidGardner]

Hunter-check your battery clampsd for tightness and corosion. I had a similar problem onetime on a gasser and that was the cure. Had to replace the battery cables to fix it. Also check your grounds. If they are bad they can cause a variety of electrical problems.



Let us know what you find.

 

[matches]

Check the grounds first, then test your voltage regulator, and alternator. My truck was doing the same thing and it turned out to be my voltage regulator. My volt guage was also jumping all over the place. It doesn't sound like its your heater relays cycling, because it kept doing it after it warmed up.

 

[Hunter4x4]

Well, I check the battery terminals, and the positive was loose. Cleaned 'em both, buttoned it all up, and no change. Battrery voltage while running is 14. 5 volts, and after shutting down for a half hour the batter is right at 13. 6 volts. When running and checking the battery voltage on a good analog VOM, you can see the needle jump back forth - probably a 0. 1 volt movement or less.



Regarding checking the voltage regulator, I thought these had an integral regulator in the alternator?



Any other ideas?



Thanks!

 

[1stgen4evr]

voltage regulator

I think the 91 has the voltage regulator on the fire wall near the wiper motor. Later the regulator is incorporated into the computer and that isn't good either. None of our first gen trucks have an integral regulator like the delco system. The chrysler regulator is notoriously poor. You can get an add on regulator that is fitted to the alternator. I am using one and like it.



James

 

[matches]

James is correct, the regulator is on the fire wall, about 2" to the left of center. Get a new one for around $20. 00. Fixed my problem.

 

[dshawhan]

I am working on a friends 91 and his voltage gauge is at like 18 and lights flicker and there is a clicking noise in the dash could this regulator be the problem? Thanks for any help. Dan

 

[1stgen4evr]

flicker

The volatagr regulator can cause flicker but would not produce an audible click as it is solid state. The light switch is prone to trouble as there is a good bit more on the switch than what it is designed for. I have changed the switch on mine more than once. Hate to steer you wrong but it could be something other than the regulator. Post your findings. Others have posted similar problems and would benefit from your result.



By the way, you do know about the lights diming when the grid heaters kick in. That is a thunk not a click.



James

 

[Hunter4x4]

Thanks for all the input - we're not done yet, though!!!



I checked the voltage regulator Sunday and that wasn't the problem. (There's no audible clicks anywhere in my situation). We had a warm spell - hi 40's - and the problem still persists.



I checked a number of connections and grounds, but couldn't find anything.



The grid heaters are working fine - come on when it's cold and cycle 3 or 4 times as the engine warms up.



So I'll keep tinkering, but for now - except for the very faint flicker - I'll just keep driving her.



As I find thing out I'll come back and post, and again, I'd appreciate any additional ideas.

 

[Hunter4x4]

A quick PS to my most recent post - I picked up a voltage regulator for $10.

 

[Hunter4x4]

Update!!!!

Well, it took a lot longer than I thought, but I have some answers to the problem!! And because it was one of those problems that wasn't crtitical to the vehicle I only worked at it off and on.



But as promised, here's what I've found - hopefully it'll help someone else down the line!!!



I checked all the stuff that everyone indicated, plus a few more, and no change.



I actually fell into the solution, when the dome light started shorting out. What I found was that about 14 years ago in the assembly plant the driver side outer seatbelt bracket was bolted over the wiring harness from the back of the cab to the dash!!! I broke the wires down, found where the insulation was compromised among a couple different wires, repaired those, and my flickering problem is about 90% gone!!



Obviously the fact that it's not gone 100% means I have some more issues, but I definitely have a line on what to look for now!!!!



Mike

 

[BHiggins]

I ran into the same problem on my 1990, it turned out to be the small ground wire that goes from the negative battery post to the radiator support. After a clean and re-tighten the flickering went away. The wire and contact looked fine upon inspection, but apparently it wasn't getting a 100% ground because as I said the problem went away immediately after re-tightening. Try it, it may be that simple... it was for me.