Engine/Transmission (1994 - 1998) problems with t/c lock up switch

[SFrey]

took the orange w/ black strip wire from the ecm that goes to the torque convt lock up, cut it and spliced a head light floor dimmer into the circiut. so i could keep it from locking up, then i was planning on using the other side of the dimmer to lock it up when i wanted (also was going to put a switch in line so it could work as normal). well no luck, what went wrong ?



scot

 

[Ridesamule]

What are you driving? It would help the sources at hand to supply info.

 

[Joe G.]

The '94 and '95 trucks have a 47RH transmission. Later trucks have a 47RE. The wiring for the lock up switch is different so we need to know what year truck you have.

 

[Ridesamule]

I see from your previous posts that you have a 96. I have an early 96 (11-95 as seen on the door post) and I had to get a flash (from Dealer) for my lockup switch to work correctly. Prior to the flash it would lock but not unlock unless I shifted into 2nd.



On another note assuming you did all of the research and it still did not work. There are 2 Black and orange wires. One for lock up and I think the other is for the "wait to start". You may have tapped the wrong one.

 

[biggy238]

96' with the flash here too. .



I think if it was assembled before 2-96 it has the non compatible PROM.



My truck would buck and jump and then go into limp mode whenever I hit the switch before the prom.



Turns out the new flash outlines nothing but gasser EFI revisions, but for some reason modified the shift points, lockup and of course the ability to run the lockup switch.



And yes, If you don't have the right wire in the right wire pack (there are three packs on the PCM) then you have either got the wait to start lamp or ( I forgot what the other one is)



Did you replace the relay with a jumper wire?

 

[JTEdieselram]

I did a lock up switch on my truck too. You need to connect the orange with a black stripe wire to (neg) ground not a power sorce. The red wire on the transmission harness provides positive power, and the solinoids are activated by grounding them out. It sounds silly, but I promise this will work, no codes need to be flashed, just splice and go. Hope this helps. P. S. there is a 1/8" npt pressure port on the passenger side tailhousing (one that is at the top right side if looking from the rear of the truck) that provides 1psi per mph. You can get a hobbs switch from napa for say 40psi and splice it into your lock up circuit for a nifty 40mph lockup controller. I put one on mine, and it works just as good as a $400. 00 lock up controller. Most hobbs switches are adjustable so you can play with it to get the desired lock up speed.

 

[Joe G.]

What year is your truck? It sounds like you have a '94 or '95 with a 47RH. The '96 and up had a 47RE. The early '96 trucks would not work without a reflash of the PCM. All of the 47RE equiped trucks required that the relay be replaced with a jumper wire. That relay does not exist on the 47RH equipped trucks. Also the solenoid setup is different on the valve body on the 47RE equipped trucks.

 

[Howard Durand]

The pressure switch controller is a new one to me. Probably cheaper than the vehicle speed sensor that I am using. Even so, I like mine because I can set it for any vehicle speed that I like with a knob on the dash.

Either way, being able to control lockup is very helpful, especially when you can also control the OD shift points.