Hey guys I need your help. This past week I got a new Hughes performance 700r4 and 12'' lockup style 2500 rpm stall converter. The new set up works well execpt fot the converter. The converter will not lock up at all in 4th gear. What should I check on the car to fix this problem.

 

I took my car to the trans shop today. The harness connections to the trans are working. My next step is to see if the computer is not working properly or if the harness is shorted out some place else. Has anybody else had an issue with the converter not locking at all? The trans shop told me to go back to the GM dealer and let them solve it.

 

Rig a test light to see if the ECM is commanding lockup. Wrong PROM, wiring issues could lead to this.

Depending on year etc., there's a 4th gear pressure switch in many OD / TCC GM transmissions that's part of the circuit to enable TCC lockup. That needs checked.

In all seriousness, you can probably search a lot on here and figure it out eventually. However, if it's a car you'll own for a while, try and score the factory service manual(s) (I'm cheap and check eBay but have bought directly from Helms too) so you can troubleshoot by using the most efficient step-by-step process to figure it out.

 

Thanks for the help. Yeah I intend on keeping my car for a long time. I've owned my car for the past 11 years. I'm going to look through the service manual that I have. Your are right. At this point I am leaning towards a wiring issue or the computer. I would have to run through the check list in the service book to be sure.