Circuit Description
Ignition voltage is provided to the torque converter clutch pulse width modulated (TCC PWM) solenoid valve. The PCM controls the ON and OFF time of the solenoid by providing a ground through the output driver module (ODM). The PCM uses a PWM duty cycle, in order to control application and release of the TCC. When the solenoid is commanded OFF, the PCM senses high volts. When the solenoid is commanded ON, the PCM senses low volts.
If the PCM detects a continuous open, short to ground or short to voltage in the TCC PWM solenoid valve circuit, then DTC P1860 sets. DTC P1860 is a type B DTC.
Conditions for Running the DTC
| • | The system voltage is 8-18 volts. |
| • | The engine run time is greater than 5 seconds. |
| • | The TCC PWM solenoid valve duty cycle is 10 percent or less or 90 percent or greater. |
Conditions for Setting the DTC
The TCC PWM solenoid valve feedback circuit indicates a continuous open, short to ground or short to voltage for 4.3 seconds.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. |
| • | The PCM inhibits 4th gear when the transmission is in hot mode. |
| • | The PCM freezes transmission adapt functions. |
| • | The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records. |
| • | The PCM stores DTC P1860 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met. |
Conditions for Clearing the MIL/DTC
| • | 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. |
| • | The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring. |
| • | The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the PCM and the wiring to the AT inline 20-way connector.
-
This step tests the control circuit for a short to voltage.
-
This step tests the circuit for correct resistance.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls | ||||||||
2 |
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the PCM. Is DTC P1842 or P1845 also set? | -- | Go to Step 3 | Go to Step 8 | ||||||||
3 |
Refer to Wiring Repairs in Wiring Systems. Did you find the condition? | -- | Go to Step 4 | Go to Step 6 | ||||||||
4 |
Important: The condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics in Wiring Systems for complete circuit distribution. Test the ignition 1 voltage circuit (CKT 839) of the TCC PWM solenoid valve for a short to ground between the underhood fuse block and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 5 | ||||||||
5 |
Important: The condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics in Wiring Systems for complete circuit distribution. Test the ignition 1 voltage circuit (CKT 1135) of the TCC PWM solenoid valve for a short to ground between the AT inline 20-way connector and the TCC PWM solenoid valve. Refer to Circuit Testing in Wiring Systems. Did you find the condition? | -- | Go to Step 22 | -- | ||||||||
6 | Test the ignition 1 voltage circuit (CKT 839) of the TCC PWM solenoid valve for an open between the underhood fuse block and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 7 | ||||||||
7 | Test the ignition 1 voltage circuit (CKT 1135) of the TCC PWM solenoid valve for an open between the AT inline 20-way connector and the TCC PWM solenoid valve. Refer to Circuit Testing in Wiring Systems. Did you find the condition? | -- | Go to Step 22 | -- | ||||||||
8 |
Refer to Automatic Transmission Inline Harness Connector End View . Is the test lamp ON? | -- | Go to Step 9 | Go to Step 11 | ||||||||
9 |
Is the test lamp ON? | -- | Go to Step 10 | Go to Step 24 | ||||||||
10 | Test the control circuit (CKT 422) of the TCC PWM solenoid valve for a short to ground between the PCM connector C2 and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | -- | ||||||||
Using the scan tool, cycle the TCC PWM solenoid valve ON and OFF three times. Does the test lamp cycle ON and OFF as commanded? | -- | Go to Step 16 | Go to Step 12 | |||||||||
12 | Is the test lamp always OFF? | -- | Go to Step 13 | -- | ||||||||
13 | Test the TCC PWM solenoid control circuit (CKT 422) and the Ignition 1 voltage circuit (CKT 739) for an open between the PCM connector C2 and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 14 | ||||||||
Connect a test lamp from terminal T of the J 44152 to ground. Refer to Automatic Transmission Inline Harness Connector End View . Is the test lamp ON? | -- | Go to Step 15 | Go to Step 24 | |||||||||
15 | Test the control circuit (CKT 422) of the TCC PWM solenoid valve for a short to voltage between the PCM connector C2 and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 25 | -- | ||||||||
Refer to Automatic Transmission Inline Harness Connector End View . Is the resistance within the specified range? | 10-15 ohms | Go to Step 19 | Go to Step 17 | |||||||||
17 | Is the resistance greater than the specified value? | 15 ohms | Go to Step 18 | Go to Step 19 | ||||||||
18 |
Refer to Circuit Testing in Wiring Systems. Did you find a condition? | -- | Go to Step 22 | Go to Step 23 | ||||||||
19 | Measure the resistance from terminal T of the J 44152 to ground. Refer to Automatic Transmission Inline Harness Connector End View . Is the resistance less than the specified value? | 100 ohms | Go to Step 20 | Go to Step 21 | ||||||||
20 | Test the control circuit (CKT 418) of the TCC PWM solenoid valve for a short to ground between the AT inline 20-way connector and the TCC PWM solenoid valve. Refer to Circuit Testing in Wiring Systems. Did you find a condition? | -- | Go to Step 22 | -- | ||||||||
21 | Measure the resistance between terminal T and all other terminals, except terminal U, of the J 44152 . Refer to Automatic Transmission Inline Harness Connector End View . Is the resistance between terminal T and any other terminal, except terminal U, less than the specified value? | 100 ohms | Go to Step 22 | Go to Step 23 | ||||||||
22 |
Important: The automatic transmission wiring harness consists of two separate harnesses, the Automatic Transmission Wiring Harness Assembly, GM P/N 15320475 and the Automatic Transmission Wiring Extension Harness Assembly, GM P/N 15320478. In order to avoid the unnecessary replacement of parts, only replace the Automatic Transmission Wiring Harness Assembly, GM P/N 15320475. Replace the automatic transmission wiring harness. Refer to Transmission Overhaul in the 4T80-E section of the Transmission Unit Repair Manual. Did you complete the replacement? | -- | Go to Step 25 | -- | ||||||||
23 | Replace the TCC PWM solenoid valve. Refer to Transmission Overhaul in the 4T80-E section of the Transmission Unit Repair Manual. Did you complete the replacement? | -- | Go to Step 25 | -- | ||||||||
24 | Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls. Did you complete the replacement? | -- | Go to Step 25 | -- | ||||||||
25 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK | Go to Step 1 |
