Ok, lets do some reading comprehension.
His truck will start. I don't know where you come from, but the starter pulls a lot more AMPs than a pair ofheadlights. Logic says, "if he can start his truck, and it will run, I don't think its the battery that is causing the headlights to not come on."

You are correct, the computer does control output from the alternator, but it doesn't effect the circuit that goes straight from the battery to fuse, to the headlight switch, to the headlights. I could go home right now, take out my trucks computer and still operate the headlights and brake lights just fine.

So, I will make a list of the problems he said he has:
-horn is dead
-tach is stuck
-abs light and brake light is on
-no brake lights
-no head lights
-No radio.
-all other gauges work and signals/flashers.
-sometimeshe can start it and the tach will work. But whenhe pulls the headlight switch or hits the brake pedal it will automatically stop the tach gauge to where ever its at.

Now, I will tell you what the computer may actually have an effect on, for real:
Tach.
[That's it.]

ABS/Brake light controlled by the ABS module. [Brake light can also be controlled by the parking brake, but not the ABS light]

Or, it might be that I can't read wiring diagrams.. you know, I guess I was missing the "secret" wire that runs from the headlight switch to the PCM that controls the headlights. And the one running from the brake switch to the PCM. You know, the ones that don't exist.

*edit*
I would actually love to stick to computers, but my laptop is currently 8,000 miles away, sitting in my truck.

 

CAN'T WE ALL JUST GET ALONG??????????? LOL


[sm=deadhorse.gif]


YA'LL NEED A DRINK!

[sm=icon_cheers.gif]

 

I'd love a drink, but where I'm at, its illegal.

 

you described my problem exactly (6 months later)
All these apperently unrealted things happened at once...making them related-
Did you ever get a solution?

 

Any chance that in the take out, clean up, and replacement of the dash, that a common ground (if one exists) either got disconnected or loosened to the point it is not making good contact?? Just throwing it out there. It sounds like he started out with a bad ignition switch, and stuff went downhill after he took it apart and cleaned it. Just my 2 Abe Lincolns, tho.

 

take the cover off dash remove light switch on the plug there is a red& white that should be hot all the time the fuse a 50 amp in pdc fuse box under hood check first if fuse is good wire is hot check with test lite . take a jumper wire an jump from red&white wire to H prong on wire plug look onlight switch the male prong is marked with H when jumped the lights should work if they do buy a new light switch happy wires if lights dont work after i will watch post i will tell you where to go

 

dodgerules86 is right and i'm wrong (thank god i'm man enough to admit it) the lights are not on the same system as the computer. you probably have a short somewhere.

thanks for the chuckle partsman 31523

paul