05 GMC 4500 TCC Issues

[gmpat21]

Im working on an 05 GMC 4500. It sets the following codes when pulling a trailer with a skidloader on. P0741 TCC circuit performance or stuck off
p2764 TCC pressure control solenoid control circuit low
p2761 TCC pressure control solenoid circuitl open

Ive checked the circuits from the TCM to the trans connector-ok
I dropped the pan and commanded the TCC solenoid with my scantool-ok
measured resistance of TCC solenoid-ok

Reinstalled pan with new internal filter and bushing. Refilled and roadtested without a trailer. No codes and trans shifted fine. Codes reset two days later when pulling trailer and skidloader. Ive referred to the tsb about the stator shaft rotating in the pump housing???? any input would be great? thanks guys!

 

[Mike L.]

Im working on an 05 GMC 4500. It sets the following codes when pulling a trailer with a skidloader on. P0741 TCC circuit performance or stuck off
p2764 TCC pressure control solenoid control circuit low
p2761 TCC pressure control solenoid circuitl open

Ive checked the circuits from the TCM to the trans connector-ok
I dropped the pan and commanded the TCC solenoid with my scantool-ok
measured resistance of TCC solenoid-ok

Reinstalled pan with new internal filter and bushing. Refilled and roadtested without a trailer. No codes and trans shifted fine. Codes reset two days later when pulling trailer and skidloader. Ive referred to the tsb about the stator shaft rotating in the pump housing???? any input would be great? thanks guys!

If the stator shaft twisted you would be having C1/C2 codes as those clutches are fed through that shaft. I am guessing bad converter clutch.

 

[Evan@InglewoodTrans]

This conversation sounds familiar.

 

[Mike L.]

This conversation sounds familiar.

Bad dream buddy? :roflmao::hug:

 

[Evan@InglewoodTrans]

Bad dream buddy? :roflmao::hug:

 

[duratothemax]

I'm suspicious though because "Circuit" codes are indicative of an electrical problem...not a mechanical problem. The TCM is reporting a problem with the solenoid itself (or the wiring between the TCM and the solenoid) Have you tried a different TCM?

 

[gmpat21]

Tcc

i agree. im not one to do the parts shotgun approach. maybe the tcc solenoid temperatur vs resistance is wacking out under load or its going completely open??? However it does come down to a rebuild and converter thats fine too id just like to pinpooint exactly the issue.

 

[duratothemax]

i agree. im not one to do the parts shotgun approach. maybe the tcc solenoid temperatur vs resistance is wacking out under load or its going completely open??? However it does come down to a rebuild and converter thats fine too id just like to pinpooint exactly the issue.

You said this is on an 05....but those appear to be 2006+ 4th gen TCM codes.

Drive it until it sets the code. Then, right after it sets the code, try commanding TCC on with the scan tool.

I would try to see if you can find a spare TCM to test it with. Im still convinced this is an electrical problem. If it was a mechanical problem, it should only set P0741, without the associated circuit-fault codes.

 

[Evan@InglewoodTrans]

You said this is on an 05....but those appear to be 2006+ 4th gen TCM codes.

Drive it until it sets the code. Then, right after it sets the code, try commanding TCC on with the scan tool.

I would try to see if you can find a spare TCM to test it with. Im still convinced this is an electrical problem. If it was a mechanical problem, it should only set P0741, without the associated circuit-fault codes.

I recently had a p0742 that was a bad converter.

 

[duratothemax]

I recently had a p0742 that was a bad converter.

P0741/P0742...similar DTC's, one is for TCC stuck on, the other is for stuck off.

Both of which are mechanical problems with the TCC, or some other hydraulic problem.

Its the 2761/2764 that denote a problem with the wiring and/or solenoid (or TCM)

The equivalent CIRCUIT (ie, wiring/solenoid) code on a 5-speed is P0743. The reason the 5-speed only has one, is because the 5-speed TCM just supplies ignition + voltage to the TCC and only has a low-side driver controlling the solenoid. So the electronics can only run diagnostics on one side of the circuit. Whereas the 6-speed TCM has not only a low side driver, but a high side driver too, so it can provide more accurate diagnostics of the entire circuit, not just the control (ie, low side) portion.

 

[Mike L.]

P0741/P0742...similar DTC's, one is for TCC stuck on, the other is for stuck off.

Both of which are mechanical problems with the TCC, or some other hydraulic problem.

Its the 2761/2764 that denote a problem with the wiring and/or solenoid (or TCM)

The equivalent CIRCUIT (ie, wiring/solenoid) code on a 5-speed is P0743. The reason the 5-speed only has one, is because the 5-speed TCM just supplies ignition + voltage to the TCC and only has a low-side driver controlling the solenoid. So the electronics can only run diagnostics on one side of the circuit. Whereas the 6-speed TCM has not only a low side driver, but a high side driver too, so it can provide more accurate diagnostics of the entire circuit, not just the control (ie, low side) portion.

P0743 is a shorted F trim solenoid on a 5 speed.