last week I had my tranny rebuilt with suncoast parts. I had to reuse the electronics on my old valvebody because they didn't have any with new electronics in stock. I put it all back together and everything ran fine, but it seemed to me like it was shifting into OD a little high. My rebuilder drove it and said that it was fine. However, two days later with less than 100 miles on the rebuild, it won't shift into OD at all. It acts like the OD off switch is just not telling it to shift. I know that the rebuild is good because it worked really well until it just stopped. My TC engages at around 55-58, but I can wind it all the way up to 70 with no OD shift. I checked the TPS, and it was reading 3.5 volts at WOT, which is a little low but should still work to shift since it shifts into OD well below WOT. It sounds like an electrical problem to me. Any suggestions?

 

Maybe a bad tranny temp sensor or the wiring to it.
If you unplug the sender and jump across the wires going to the PCM with a 1000 ohm resistor it will trick the PCM into thinking the fluid is warm enough to shift into OD.

 

Thanks, I'll try that.

 

Here's what I tried today:
-1k Ohm resistor in place of trans temp sensor
-1k Ohm resistor in place of intake temp sensor
-5k Ohm pot in place of TPS with shielded wire in case TPS had a dirty signal
-cleaned ground connection on top of engine by cylinder 1

Still no luck. My trans guy said it could be the solenoid on the valvebody since we used the old one, but it doesn't make sense why it would work for two days and then just quit. He also said that the valvebody looked like it had been sitting on the shelf at suncoast for a while because a couple valves were a little sticky. However, they worked for two days and the tranny fluid should have lubed them up pretty good. Anybody else have any ideas?

 

My guess would be solenoids. They are known to go out.

Have your trans guy do a pressure check while driving.

 

I took it to my tranny guy this weekend. Turns out that the outer overdrive clutch piston seal o-ring failed.