Cliff notes...

2000 GMC Sierra 1500, original 4.8/60E truck. 6L/80E swapped. PCM of NC adapter harness was used. 2nd one just took a crap. It is now my truck, bought it in April. Said F it, segment swap. Got the tune sorted - I think. Added the 2nd speed sensor and the short pigtail to go between the transmission and factory harness plug. (Was going to repin the factory plug, but I'm lazy)

Getting an intermittent P01860 code. Never pops up while driving, if I shut the truck off and restart it - pops up within seconds. Converter will not lock, I have even tried to do it manually with HPT. I replaced the internal harness and the TCC solenoid. No dice. What is my next move?

I can post the most recent data log and tune file if need be.

TIA

 

4L80-E / 4L85-E Automatic Transmission

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

Schematic:

CIRCUIT DESCRIPTION
The Torque Converter Clutch Pulse Width Modulation (TCC PWM) solenoid valve controls fluid acting on the converter clutch valve, which then controls TCC apply and release. The TCC PWM solenoid valve attaches to the control valve body within the transmission. Ignition voltage goes directly to the TCC PWM solenoid valve. The Powertrain Control Modulator (PCM) controls the TCC PWM solenoid valve by providing a ground path on circuit 418. The current flows through the TCC PWM solenoid valve coil according to the duty cycle (percentage of ON time). The TCC PWM solenoid valve provides a smooth engagement of the torque convener clutch by operating on a duty cycle percent of ON time.

If the PCM detects a continuous open or short in the TCC PWM solenoid valve circuit or the TCC PWM solenoid valve, then DTC P1860 sets. DTC P1860 is a type C DTC. For California emission vehicles DTC P1860 is a type A DTC.

CONDITIONS FOR RUNNING THE DTC
^ The system voltage is 8.0-18.0 volts.
^ The engine is running greater than 300 RPM for greater than 7 seconds.
^ No shift solenoid DTCs P0751, P0753, P0756, or P0758.

CONDITIONS FOR SETTING THE DTC
All conditions for running the DTC are met, and either of the following conditions occur for 4.3 out of 5 seconds.
^ The PCM commands the TCC PWM solenoid valve to OFF (0%) and the voltage input remains low (0 volts).
^ The PCM commands the TCC PWM solenoid valve to ON (100%) and the voltage input remains high (B+).

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the malfunction indicator lamp for California emission vehicles.
^ The PCM inhibits TCC engagement.
^ The PCM inhibits 4th gear if TFT is greater than 130°C (266°F).
^ The PCM freezes shift adapts from being updated.
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame (Calif. only) and Failure Records (Calif. and Federal).
^ The PCM stores DTC P1860 in PCM history.

CONDITIONS FOR CLEARING THE MIL/DTC
^ For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
^ A scan tool can clear the MIL/DTC.
^ For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without an emission related diagnostic fault occurring.
^ For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-emission related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

DIAGNOSTIC AIDS
^ First diagnose and clear any engine DTCs or TP sensor codes that are present. Then inspect for any transmission DTCs that may have reset.
^ Inspect the connectors at the PCM, the AT wiring harness and all other circuit connecting points for an intermittent condition. Refer to Testing for Intermittent and Poor Connections in Diagrams.
^ Inspect the circuit wiring for an intermittent condition. Refer to Testing for Electrical Intermittents in Diagrams.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
4. This step tests for voltage to the TCC PWM solenoid valve circuit at the 20-way connector.
6. This step tests the ability of the PCM and wiring to control the ground circuit.
8. This step tests the resistance of the TCC PWM solenoid valve and the internal wiring harness.

 

Did it lock fine before the seg swap?

 

Yes, until the PCM of NC harness shorted out it drove fine. Shifted all gears, converter locked up in 4th.

I had someone suggest that it may have hurt the PCM? Seems like a reach.

 

And it wont lock with BiDi controls either?

 

Not sure what those are? I tried with HP Tuners, it did nothing.

 

Bi-Directional? Maybe?

 

Yea thats called Bi Directional controls.
If it didnt work with that i would check for ground at the 20 pin connector (Pin S) while using the scanner to command it locked. That would let you know if the PCM is good/bad.

 

I swapped in my spare PCM this morning and flashed it with my tune file. Still does the same thing. My next move is to eliminate the adapter harness between the factory harness and the connector on the 4L80E.

I really do not know what else it could be at this point. I'll post up my tune file for anyone that is interested.

 

My current tune if anyone is bored or curious.