Head lights connected to the - torque converter!

[stever8761]

Anyone know why the torque conv bounces in and out of lock up when the head lights are on! (And only when the lights are on!) It's a flat bed w/stepside style tail lights and a plug in adapter for a four prong trailer plug. (Which I'm about to remove to check for any differance.) It happens in both OD and OD Off modes.

 

[scheid6996]

i dont think it has anything to do with your tailights, there must be a short somewhere els, like your trans controll, maybe your fuse box is messed up, and when u put power the the head light fuse it does something to your trand controll

 

[Double-S-Diesel]

actually had this problem in A psd.
the liscence plate light wire was busted.
these COMPUTERS that controll the trans and TC function are sensitive to any voltage that seems like the brakes are on,
just having a light bulb out will cause trouble.
Goos luck , start checking lights, and grounds.
Nick

 

[93turbo_animal]

yep my buddys PSD's auto would go into limp mode when he used his hazards so check light bulbs and connections also where the wires from the gear knob go over the column can get rubed bare an I think it ties in with the multifunction switch there somewhere too

 

[geonc]

Seeings how the brake/tail lights are tied into the converter lock up... ....it is quite possible that the trailer wiring/trailer brake controller could very well be the culprit.

A check of the headlight switch is in order as well....look for melted connector plug at back of switch.

My '93 IDI lost a tranny due to your very same problem.

 

[stever8761]

Soooo. Doing my test last night (removing the trailer plug adapter) the trans worked fine! Went to the parts store to get a HD flasher. He hands me the exact same one that is already in the truck. Then says we have this electric flasher . While in the parking lot at the parts store, I reconnected the adapter and the new flasher and drove home - all was good! Next test was with the trailer hooked up! The drive in this morning (with trailer) was the smoothest morning ride I have had in a long time. I do have a short in the left tail/brake light, so I'll be rewiring that in the next couple of days! Thanks for the help!!

 

[scheid6996]

oh, man i had no idea that a lihg tbulb could mess with the trans, i feel like a dummy now

 

[Mr_Roboto]

One of my trucks does the same thing with my tow dolly hooked up, when I use the turn signal the torque converter unlocks. I know what the problem is, one of the bulbs in the dolly is burned out and the filament is touching.

Any time there is power in the brake light circuit the converter clutch unlocks. Drives me nuts.

 

[93turbo_animal]

No worrys Chris thats why we're here get in to the PSD's and your electrics can do some really weird things

 

[geonc]

If ya really want to prove that the lighting/brakes has a effect on the torque converter.......

With the tranny in O/D and traveling above lock up speeds......above 40 or so......turn on the emergency flashers and watch the tach that little pulse is the converter locking/unlocking .
That will beat the snot out of the front pump, converter etc...

Now think of all those people that run with their flashers on in rain storms etc