Circuit Description
The torque converter clutch pulse width modulation (TCC PWM) solenoid valve controls the fluid acting on the converter clutch valve. The converter clutch valve controls the TCC application and release. The solenoid attaches to the control valve body within the transmission. The solenoid receives ignition voltage through the OFF/ON/START voltage circuit. The powertrain control module (PCM) controls the solenoid by providing a ground path on the TCC PWM solenoid valve control circuit. Current flows through the solenoid coil according to the duty cycle, percentage of ON and OFF time. The TCC PWM solenoid valve provides a smooth engagement of the TCC by operating during a duty cycle percent of ON time.
When the PCM detects a continuous open, short to ground or short to power 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 10-18 volts. |
| • | The engine speed is greater than 450 RPM for 5 seconds. |
| • | The engine is not in fuel cutoff. |
| • | The PCM commands first gear. |
| • | The TCC duty cycle is less than 10 percent or greater than 90 percent. |
Conditions for Setting the DTC
DTC P1860 sets if one of the following conditions occurs for 5 seconds:
Condition 1
The PCM commands the solenoid ON, 90 percent, and the voltage feedback remains high, B+.
Condition 2
The PCM commands the solenoid OFF, 0 percent, and the voltage feedback remains low, 0 volt.
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 TCC engagement. |
| • | The PCM inhibits 4th gear if 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 for voltage to the solenoid.
-
This step tests the ability of the PCM and wiring to control the ground circuit.
-
This step tests the resistance of the TCC PWM solenoid valve and the automatic transmission wiring harness assembly.
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. Are any of the following DTCs also set?
| -- | Go to Step 3 | Go to Step 4 | ||||||||
3 | Inspect the TRANS fuse for an open. Refer to General Electrical Diagnosis in Wiring Systems. Is the fuse open? | -- | Go to Step 11 | Go to Step 4 | ||||||||
Refer to Automatic Transmission Inline Harness Connector End View . Does the test lamp illuminate? | -- | Go to Step 5 | Go to Step 14 | |||||||||
Refer to Automatic Transmission Inline Harness Connector End View . Does the test lamp turn ON and OFF with each command? | -- | Go to Step 7 | Go to Step 6 | |||||||||
6 | Is the test lamp always ON? | -- | Go to Step 15 | Go to Step 16 | ||||||||
Refer to Automatic Transmission Inline Harness Connector End View . Does the resistance measure within the specified range? | 10-15 ohms | Go to Step 8 | Go to Step 9 | |||||||||
8 | Measure the resistance from terminal E to ground, and from terminal U to ground. Do both readings measure greater than the specified value? | 250 K ohms | Go to Intermittent Conditions in Engine Controls | Go to Step 10 | ||||||||
9 |
Does the resistance measure within the specified range? | 10-15 ohms | Go to Step 17 | Go to Step 18 | ||||||||
10 |
Do both readings measure greater than the specified value? | 250 K ohms | Go to Step 17 | Go to Step 18 | ||||||||
11 |
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 OFF/ON/START voltage circuit (CKT 1020) of the TCC PWM solenoid valve for a short to ground between the 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 20 | Go to Step 12 | ||||||||
12 |
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 AT inline 20-way connector and the TCC PWM solenoid valve. Refer to Circuit Testing in Wiring Systems. Did you find a short to ground condition? | -- | Go to Step 17 | Go to Step 13 | ||||||||
13 |
Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||||
14 |
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 OFF/ON/START voltage circuit (CKT 1020) of the TCC PWM solenoid valve for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | -- | ||||||||
15 | Test the control circuit (CKT 418) 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 20 | Go to Step 19 | ||||||||
16 | Test the control circuit (CKT 418) of the TCC PWM solenoid valve for an open or short to power 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 20 | Go to Step 19 | ||||||||
17 | Replace the AT wiring harness assembly. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||||
18 | Replace the TCC PWM solenoid valve. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||||
19 | Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls. Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||||
20 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK | Go to Step 1 |
