'03 Mysteriously Nonfunctioning Items?

[CTieman]

Disconnected my batteries and fuse box power to do some work, now many things don't work after reconnecting?



Headlights and parking lights go on when ignition is on but won't turn off unless ign. is off.

Brake lights on bed don't work but cab brake light works.

Flashers flash on dash but not at corners.

Windshield wipers and horn don't work.

When doors are locked via key fob, parking lights don't blink like before. Tried the procedure in manual to reset and no change.



All fuses are good



Truck seems to drive fine and dealer wants at least half day dianosis at $90/hr. Anybody had anything similar or any suggestions?

 

[Blakers]

Does the computer take a little while to reprogram itself?

 

[CTieman]

I'm not sure. Ive driven approx. 150 mi and 4 hrs since problem initiated. I'd imagine the computer would have reset by then.

 

[sag2]

All the items you mention are controlled by the Front Control Module. When you had the "fuse block" out, what are you talking about? The one under the hood in front of the driver? That has the FCM connected to it, and a bunch of connectors plug into it on the bottom. Tilt it back up and check every connector to be sure it is locked in. When the FCM is missing the head light switch input it defaults to headlamps on for safety. All the other lighting wiring goes through there.

 

[CTieman]

Yes the fuse block infront of the driver. I've checked the plugs briefly. I'll do it again with more detail tomarrow as I don't have access to the truck today.

 

[p-Bar]

Try disconnecting both batt. and let it sit awhile the computer may need to be reset

 

[CTieman]

Try disconnecting both batt. and let it sit awhile the computer may need to be reset

Tryed that.

 

[CTieman]

Took it to the dealer. Turns out the FCM was bad. They couldn't tell me why it went out and cost me $500. They said another truck came in that day with a bad FCM, they said that one went bad from wiring some aftermarket trailering lights to the rear tail lights. Why is this thing so sensitive on such a heavy duty vehicle?

 

[Blakers]

Why is this thing so sensitive on such a heavy duty vehicle?

I believe all this stuff is to save money on copper wire. It adds up quick with millions of vehicles. Rather poor engineering to not allow easy upgrades. But, poor engineering is becoming the norm on new vehicles.



Blake