Common

They are REALLY flickering bad while driving, and I notice my voltage gauge is moving with the flickers...though not going below 14...

Should I get a new alternator now, or is this thing going to leave me stranded?

I need some opinions...

(Sounds like its the alternator, right?)

H2SRDMB

well not so quik. but i didnt read any other posts about the problem. but have you looked for a wire chaffing?

also look at your grid heater sticking on/turning on randomly!

alternators arnt cheap, but you can have them tested before you go that route!.

SBishop

If only flickering while driving, I would be thinking a loose cable connection somewhere.

12valve@heart

I would agree that it's unlikely to be the alternator but it's free to get one tested and then you know. Even if it is the brushes, get yours rebuilt instead of exchanging it. LOTS cheaper.

Good luck finding that loose connection

Common

You guys are right, its not the alternator.

i put a scan tool on it today and put a full load amp draw on it, and the alternator maxed out the voltmeter with no problems, ran at a steady 13.8v as well..

The only time the lights flicker is while driving, and I cannot find a loose wire or anything...

This is really annoying, I would pay one of you to fix it!

Common

Are you guys POSITIVE the voltage regulator is in the Alternator and not the PCM?

I'm stumped...

Can a headlight switch cause this?

97ramctd

mine flicker all the time but never go off totally i just don't worry bout mine it's not to bad yet. A buddy has a 96 and his kept going off totally and coming back on his was the headlight switch. His plug that went to the switch was also melted.

torquefan

The regulator is NOT in the alternator. It is indeed in the PCM. I would cell test the batteries- a dead cell can do that type of thing, also I would remove the headlight switch and have a good look at the connector. If it's been overheated, you will see it.

Common

The reason I got the Optimas was because of the flickering...

I wish I had a solution!

I'll check the light switch tomorrow...

Any other ideas?

And if it was the voltage regulator, wouldn't my radio dim as well? (aftermarket Panasonic)

shell006

If it is cold outside and truck is not warmed up it will do that it even talks about that in the owners manual of my 06 what you are describing is normal until truck warms up my 99 that i had did the same thing when it was cold it is a charactaristic of the beast

HayHauler1

Could it be the fuel heaters cycling on and off. Mine does this too, but it isn't really a flicker, they just dim slightly and then come back to bright after a few seconds. While they are dim, the stock volt meter dips too, then comes back to normal when the lights brighten up. hmmmmm.........

Hay

D2 Cat

By "flicker" do you mean the lights go off, then on? Or, do they just dim down?

If they actually go off/on and at random times, I would check the headlight switch. I had a truck with similar problems. At first the instrument cluster lights would work randomly, then the headlights would actually go off for a millisecond, then they would go off more frequently and stay off longer. Didn't take too long to get motivated to solve it when you're driving 60MPH and your lights go out.

Lil Dog

I HAD THE SAME PROBLEM on the weekend. I recently pulled some electrical on the drivers side to access the injector pump for some tweaks. After that I was going to a dyno event and on hard accelleration, I got the lights flickering, voltage drop to 12V etc. But only on hard accelleration. I have a new alternator, but it was legit for replacing, totally roasted.

Anyhow, I went back and started wiggling wires down where I was working in the hopes of finding the short or break in the wire. The only thing that has worked is the connection to the Intake Air Temp sensor. I had the wires pretty pulled over and crunched during my work. I pulled the plug, straightened the wires, cleaned the connection and now it has stopped flickering. I don't know if the PCM gets scrambled with an intermittant IAT sensor and starts cycling but I would try that.

So for your next experiment, pull the relay wires on the grid heaters so they can't come on and go for a spin. See if that helps..

Thats all I got...

TexasGoatRider

I had a '95...the main hot to the key switch pulled out of the terminal inside the steering column...I assume from constant tilting of the steering. Anyway the truck would run fine but no power to lights, radio, etc. It was an easy roadside fix. Pull the cover off the steering column and trace the big red wire.
Good luck, electrical probs are the worsed.
'96 2500 ext cab SLT 5spd...190,000 bone stock, no probs

mrclean

Check your grounds at the headlight harnesses. Just one of them disconnected can cause your problem. Then check the switch. HTH