Headlights and Driving lights controlling torque converter??

[twalker9480]

I've been having problems recently with my torque converter only locking up some of the time. Until a couple days ago i haven't been able to find any pattern or consistency to the issue. But then the other night i was driving and for some reason decided to turn off my headlights for a minute... and my torque converter locked up! At first i thought it was a coincidence, but then i started playing with the lights and i realized that if my headlights OR driving lights are on, then the torque converter will not lock up, but as soon as i turn the stalk to "off" it locks up right away. I cant seem to find any connection between the wiring of the 2 systems. This is a new problem that i haven't had the entire time i have owned my 80 (I've had it for about 45k miles, 3 years)



Does anyone have any idea what could be causing this?

 

[BILT4ME]

Sounds to me like a grounding issue.

Any engine work or anything where the (6) grounding cables may not have been reattached?

 

[twalker9480]

Sounds to me like a grounding issue.

Any engine work or anything where the (6) grounding cables may not have been reattached?

Then injector pigtails for the 5th and 6th cylinders were under the knife recently, but i was already having the problem before that.

 

[dugsgms]

Pure shot in the dark, but I wonder if one of the inputs the ECM uses to control t/c lock-up is the brake light switch. If so, I suppose a cross short between the rear running lights and the brake lights would cause such symptoms, do the rear running and brake lights work properly, if you remove the rear light bulbs does the problem go away?

 

[twalker9480]

Pure shot in the dark, but I wonder if one of the inputs the ECM uses to control t/c lock-up is the brake light switch. If so, I suppose a cross short between the rear running lights and the brake lights would cause such symptoms, do the rear running and brake lights work properly, if you remove the rear light bulbs does the problem go away?

I was actually having problems with the taillights that i couldn't figure out. I ended up doing some pretty weird wiring back there to get it close to normal functionality, long story... You could be on to something!

 

[NLXTACY]

Package it and sell it

 

[PDoyle]

But buy all the parts from Joey first.

 

[twalker9480]

But buy all the parts from Joey first.

Well of course

 

[twalker9480]

Pure shot in the dark, but I wonder if one of the inputs the ECM uses to control t/c lock-up is the brake light switch. If so, I suppose a cross short between the rear running lights and the brake lights would cause such symptoms, do the rear running and brake lights work properly, if you remove the rear light bulbs does the problem go away?

I undid all my wiring and I still have the problem (and now no breaklights) but I'm going to look more into what you're talking about

 

[Tools R Us]

Pure shot in the dark, but I wonder if one of the inputs the ECM uses to control t/c lock-up is the brake light switch. If so, I suppose a cross short between the rear running lights and the brake lights would cause such symptoms, do the rear running and brake lights work properly, if you remove the rear light bulbs does the problem go away?

Plausible, if there were a tail light ground problem, the running light could back feed through brake light circuit.

 

[Rivman1243]

Are you sure its actually locking the torque converter? Or is the tach just jumping? Will it stay locked in all gears or only a few? Have you checked your fluids? Just throwing out a few other ideas. It very well could be a tail light wiring problem

 

[twalker9480]

Are you sure its actually locking the torque converter? Or is the tach just jumping? Will it stay locked in all gears or only a few? Have you checked your fluids? Just throwing out a few other ideas. It very well could be a tail light wiring problem

When you say "are you sure its not just the tach jumping?" You mean if it's actully changing engine speed? If so than yeah definitely.

 

[inkpot]

Maybe yur rig just doesnt like those new 37s?

 

[twalker9480]

Maybe yur rig just doesnt like those new 37s?

Youre probably right! Those Toyota engineers designed our truck a specific way, they're no good for anything bigger than 275/70R16. Mabye Rosies looking to trade for some new STT Pros?

 

[twalker9480]

Alright, time to add to the mystery... If my heater has been running the torque converter locks up every time, regardless of the lights being on or off. Ive tested this several times to make sure it isn't just a coincidence.

 

[Heckraiser]

Flasher gremlin

 

[cody c]

I suspect its a poor shared ground, and the power is back feeding through other circuits. Some of the lighting circuits "kind of" ground at one end that usually see + power through when not energized.

Clean and fix your grounds up front, make sure they're bonded correctly.

 

[PDoyle]

There is a ground bolted to the body just above the spare tire .

 

[tacocat]

It appears that your rig is also in dire need of an exorcism.

Please read the following after Halloween......

The FZJ80 tail light sockets usually need a good resolder after 20+ years of hard service. I'd start there.