4L60E diagnostic help

[ikeG]

How about an 09 Silverado 1500 2wd that sets P2764(TCC Pressure Control Solenoid Low Voltage) every time it gets up to temp. Runs like a top until it reaches around 170 deg, then trips the code and goes into fail safe mode. Using Mitchells diag instructions, it points to the TCM. But i am doubting that. I cant hardly think its the TCM, the underhood temps area at their max a long time before it trips the DTC. It surely has to be internal, the solenoid itseflf?

 

[Mike L.]

High mileage?

 

[ikeG]

High mileage?

Its a reman trans, 3k on it. 165k on the tcm.

Once the trans is warm, it trips that code after clearing just sitting in the driveway.

The reman trans company doesn't want to give me a solenoid and such until external circuits are ruled out. Which, using prodemand instructions, points to the tcm

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[Mike L.]

Rare for a tcm to do that.

 

[Mike L.]

I would look at the solenoid first. I bet they used the old one over. Common practice.

 

[ikeG]

Ok thanks mike

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[KyleC4]

All solenoids get their voltage from same ign wire. Only difference being control circuit. Disconnect connector at trans, key on engine off, hook test light in between circuits for ign feed and tcc pwm solenoid and command it on and off with your scan tool. If test light turns on and off and is bright, you know your tcm an wiring are good. I’d do test multiple times too while moving harness around. Or even put your meter in line as well and see the voltage while commanding pwm from 0-90%. That way then you can tell the company everything on truck side is good.

only area i see commonly for chafed wires is on top of bellhousin where it follows evap and fuel lines. Don’t see spread terminals much on these trucks but it’s all possible. Also I hate when the reman company’s reuse the internal harness on 4L60’s. I find them to be crap as well

 

[ikeG]

All solenoids get their voltage from same ign wire. Only difference being control circuit. Disconnect connector at trans, key on engine off, hook test light in between circuits for ign feed and tcc pwm solenoid and command it on and off with your scan tool. If test light turns on and off and is bright, you know your tcm an wiring are good. I’d do test multiple times too while moving harness around. Or even put your meter in line as well and see the voltage while commanding pwm from 0-90%. That way then you can tell the company everything on truck side is good.

only area i see commonly for chafed wires is on top of bellhousin where it follows evap and fuel lines. Don’t see spread terminals much on these trucks but it’s all possible. Also I hate when the reman company’s reuse the internal harness on 4L60’s. I find them to be crap as well

Test light stays lit with tcc on or off. That indicates bad tcm. But my snap on scantool only allows me to turn tcc on or off, no 0 to 100%. When I turn tcc on, duty pid goes to 99%. When I turn it off, duty goes to 0%. I can command tcc on while driving and it works. The circuits themselves ohm out perfect, no continuity to ground.

How do you test the solenoid in the trans itself?

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[KyleC4]

The resistance of the solenoid itself should be 10-15 ohms. You can also supply power and ground to the solenoid directly with pan off and solenoid out. Put power to circuit with red wire and momentarily touch other circuit to ground. Should hear and feel a click.

 

[ikeG]

Solenoid ohms out at 10.5. I think I found a spread pin in the tcm connector. Waiting on a replacement.

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[Dean E]

Solenoid ohms out at 10.5. I think I found a spread pin in the tcm connector. Waiting on a replacement.

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Pretty sure you found your issue. If it tests fine and does not throw a code till things warm up a bit I was going to mention checking the connectors at the tranny and TCM. Shift solenoids do pull a bit of current and a weak connection would act this way and only get worse with time. Dean

 

[ikeG]

I replaced the suspect tcm connector pin but no change. As soon as atf gets warm, it trips P2764. Pulled it back in, solenoid ohms out fine again. Checked it for a short to trans case with truck harness plugged into trans connector, bingo. Tcc pwm circuit was rubbed through on top of trans where it loops over top. Thanks guys.

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[Dean E]

I replaced the suspect tcm connector pin but no change. As soon as atf gets warm, it trips P2764. Pulled it back in, solenoid ohms out fine again. Checked it for a short to trans case with truck harness plugged into trans connector, bingo. Tcc pwm circuit was rubbed through on top of trans where it loops over top. Thanks guys.

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You don't hear of those very often. Glad you found it. Dean