I am wondering if the 05 Ally has a TCC lockout like an 02 does. If so, how can I prove if it is working or not. I suspect that the TCC is not locking up even when the tranny is at operating temp.

My 05 has the same gear ratio and tire size as my brothers 02. His will indicate around 1950 RPM @ 70 MPH while mine indicates around 2150 RPM @ 70 MPH.

Thanks,

Britt

Did you mean OD Lockout? Never heard of TCC Lockout.
Shifting from OD to 4th at highway speed will increase RPM's about 600-800 RPM's, so that's not your problem.
As you stated, 200 RPM's sounds like you're not locked up.
With my 02 in winter, I drive about five miles before the tranny warms up enough to allow the torque converter to lock, which then drops RPM's about 200. Real easy to monitor with the Juice Attitude.

Do you both have the same gears?

Only ever heard of 3.73's as the only stock option. Could have been changed, not mine.

I am wondering if the 05 Ally has a TCC lockout like an 02 does. If so, how can I prove if it is working or not. I suspect that the TCC is not locking up even when the tranny is at operating temp.

My 05 has the same gear ratio and tire size as my brothers 02. His will indicate around 1950 RPM @ 70 MPH while mine indicates around 2150 RPM @ 70 MPH.

Thanks,

Britt

Do you both have the same gears?

As I said in the opening statement, same gear ratio and tire size. I suspect that the torque converter clutch has never locked up on this truck.

Rats, it looks like a trip to the dealer, & there aren't any dealers around here that I would trust with a Briggs & Stratton, let alone a DMax!

Britt

navion,

A quick way to tell if your TCC is working is to drive your truck at about 40 MPH and press the Tow/Haul switch. At 40 MPH you're below lock-up in normal mode but the TCC will engage in Tow/Haul. See if there is about a 200 RPM drop when you press the button. If you do it's working.

Your's acts like mine does and my TC locks. Does your brother possibly have a different tire size programmed into the truck than what he actually has on it?

on the highway (65 mph or so) let off the gas completely. IF the engine RPM drops to like 1100 RPM or so, the TC isnt locked. If it stays consistant with vehicle speed, its locked.

--Ben

i thought that in 04 gm offered 4.10 gears too

navion,

A quick way to tell if your TCC is working is to drive your truck at about 40 MPH and press the Tow/Haul switch. At 40 MPH you're below lock-up in normal mode but the TCC will engage in Tow/Haul. See if there is about a 200 RPM drop when you press the button. If you do it's working.

This is no help to Navion, but I tried this yesterday. When I press the T/H button the trans downshifted right away. Made it impossible to see of the TCC was locked.

Is there some trick to this test that I am missing?

No, there's no trick. You might try slowing down or speeding up a bit. There's a sweet spot in there somewhere that will maintain the same range in both normal and tow/haul mode.

on the highway (65 mph or so) let off the gas completely. IF the engine RPM drops to like 1100 RPM or so, the TC isnt locked. If it stays consistant with vehicle speed, its locked.

--Ben

Nice tip. Just as Ben said.

With my transmission temp still low, and transmission in Normal Mode, I increased speed up to 65 MPH. Let off accelerator and engine RPM drops near the 1000 RPM range.
Then, with the transmission warm, and in Tow/Haul Mode, I increased speed to 65 MPH, let off accelerator, and engine RPM's are maintained, gradually slowing, and with each downshift, (5-4, 4-3, 3-2), the engine RPM's increased. Real easy to see on the Attitude also.
COOL! Never thought about or noticed it before, but it makes sense. Thanks for the great input.

If the converter isn't locking when it should, there will be a code stored for sure. When the computer calls for lockup, if it doesn't see the trans input rpm match the engine rpm within a couple of seconds, it will code.