code P2721

On my 2005 1500LT 4WD/AWD with the tow pkg and tow shift control, the check engine light has been on for months, with the most recent code of P2721.....pressure control solenoid circuit high. I'm getting ready to pull the pan and check all the solenoids (had a P0740 before this, and it's wandering quite a bit between 3rd and OD), but I'm not convinced the units themselves are actually bad. I plan to have at least the TCC/PWN, TCC, and EPC solenoids on hand PLUS a new inner harness for them.

Stil....because all the codes I have had, or made note of in the past, are power/current related I suspect there might be a problem with the connections or wiring from back much further toward the ignition or battery. Any stories of experience with this issue would be appreciated. The other code I had noted was P1860, but I can't remember if was actually one I had read. It had the typical wandering shift at 45 mph on slight grades, but has now been doing the same at speeds as high as 70.

102,000 miles, fluid changed last year to Dex VI.

On my 2005 1500LT 4WD/AWD with the tow pkg and tow shift control, the check engine light has been on for months, with the most recent code of P2721.....pressure control solenoid circuit high. I'm getting ready to pull the pan and check all the solenoids (had a P0740 before this, and it's wandering quite a bit between 3rd and OD), but I'm not convinced the units themselves are actually bad. I plan to have at least the TCC/PWN, TCC, and EPC solenoids on hand PLUS a new inner harness for them.

Stil....because all the codes I have had, or made note of in the past, are power/current related I suspect there might be a problem with the connections or wiring from back much further toward the ignition or battery. Any stories of experience with this issue would be appreciated. The other code I had noted was P1860, but I can't remember if was actually one I had read. It had the typical wandering shift at 45 mph on slight grades, but has now been doing the same at speeds as high as 70.

102,000 miles, fluid changed last year to Dex VI.

CODES SHOUD BE CLEARED AND DROVE AND SEE WHAT CODE COMES BACK.

Post back what code no come back.

I remember one forum member had many tranny codes. it was the ignition switch. could also be wires/connector to the tranny.

I remember one forum member had many tranny codes. it was the ignition switch. could also be wires/connector to the tranny.

Yes, I remember that one. The common denominator seems to be electrical, but it seems to be having several different targets. I'll know more when we get a look at all the connections I guess.

And, I will have another reading before I did in. ;)

Hmmmmm....???

Maybe this goes a little deeper. As I left the parts store yesterday I hade a u-turn at the mid-block turnout, and after getting straight I had to accelerate hard for approaching traffic. I took it up to speed (45 on this blvd) quickly and then coasted to the next red light. When I left the light it hesitated noticeably (about a second or two) and then made a soft "clunk" when going into gear. UGH! Now, what? The rest of the way back it didn't do it again, but I think it did have a hesitation on a shift between 1-2 or 2-3 earler in the week....which I ignored as "wandering" a bit due to the TCC issue.

But this pause-clunk really concerns me. Any relation to the TCC issues, or a whole new problem???

Hmmmmm....???

Maybe this goes a little deeper. As I left the parts store yesterday I hade a u-turn at the mid-block turnout, and after getting straight I had to accelerate hard for approaching traffic. I took it up to speed (45 on this blvd) quickly and then coasted to the next red light. When I left the light it hesitated noticeably (about a second or two) and then made a soft "clunk" when going into gear. UGH! Now, what? The rest of the way back it didn't do it again, but I think it did have a hesitation on a shift between 1-2 or 2-3 earler in the week....which I ignored as "wandering" a bit due to the TCC issue.

But this pause-clunk really concerns me. Any relation to the TCC issues, or a whole new problem???

with the dtc p0740 you must have 12 volts to the TCC solenoid valve at all times. when the voltage is not there this will throw this code so it starts at the ignition switch and goes to a fuse to the tranny connector to the solenoid...

Turns out the code was actually 2761...related to the TCC/PWM voltage/current. I had my son track the power from the ign fuse and PCM back down to the tranny connection. It had low voltage readings during cranking, but that was apparently due to a dying battery. We replaced the battery and checked the current at the last connection again, but now i can't remember the exact readings. We ran out of time (Christmas eve), and the CEL came back on, so the next step is a look at the selenoid harness and TCC/PWM selenoid I guess.

In the meantime the poor TC lockup continues.