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 module (PCM) controls the TCC PWM solenoid valve by providing a ground path on the control circuit. 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 converter 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 and vehicles under 8,600 GVW, DTC P1860 is a type B DTC.
Conditions for Running the DTC
| • | The system voltage is 8-18 volts. |
| • | The engine is running for greater than 7 seconds. |
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 percent, and the voltage input remains low, zero volts. |
| • | The PCM commands the TCC PWM solenoid valve to ON, 100 percent, and the voltage input remains high, B+. |
Action Taken When the DTC Sets
| • | For California emission equipped vehicles, 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 commands increased line pressure. |
| • | 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, California only, and Failure Records, California 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 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 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
DTC P1860 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests for voltage to the TCC PWM solenoid valve circuit at the 20-way connector.
-
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 internal wiring harness.
Step | Action | Value(s) | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls - 6.0L | ||||||||||
2 |
Important: Before clearing the DTCs, 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. Refer to Circuit Protection - Fuses in Wiring Systems. Is the fuse open? | -- | Go to Step 3 | Go to Step 4 | ||||||||||
3 | Inspect the following components for a short to ground:
Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Intermittent Conditions in Engine Controls - 6.0L | ||||||||||
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 5 | |||||||||||
5 | Repair the open or high resistance in the ignition 0 voltage circuit (CKT 1020) of the TCC PWM solenoid valve. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 20 | -- | ||||||||||
Does the test lamp illuminate when you command the TCC PWM solenoid valve ON, and go out when you command the TCC PWM solenoid valve OFF? | -- | Go to Step 10 | Go to Step 7 | |||||||||||
7 | Is the test lamp always ON? | -- | Go to Step 9 | Go to Step 8 | ||||||||||
8 | Test the control circuit (CKT 418) of the TCC PWM solenoid valve for an open or short to voltage between the PCM connector C2 and the AT inline 20-way connector. Refer to Circuit Testing in Wiring Systems and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 11 | ||||||||||
9 |
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 11 | ||||||||||
Does the resistance measure within the specified values? | 10-15 ohms | Go to Step 13 | Go to Step 12 | |||||||||||
11 | Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 6.0L. Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||||||
12 |
Does the resistance measure within the specified values? | 10-15 ohms | Go to Step 14 | Go to Step 18 | ||||||||||
13 | Measure the resistance between terminal S of the TCC PWM solenoid valve and ground. Does the resistance measure greater than the specified value? | 250 K ohms | Go to Step 16 | Go to Step 15 | ||||||||||
14 | Test the automatic transmission wiring harness assembly for an open circuit. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find a condition? | -- | Go to Step 19 | -- | ||||||||||
15 |
Do both readings measure greater than the specified value? | 250 K ohms | Go to Step 17 | Go to Step 18 | ||||||||||
16 | Measure the resistance between terminal S and all other terminals, except terminal A, B, and E of the J 44152 . Refer to Automatic Transmission Inline 20-Way Connector End View . Is the resistance between terminal S and any other terminal, except terminal A, B, and E less than the specified value? | 250 K ohms | Go to Step 17 | Go to Intermittent Conditions in Engine Controls - 6.0L | ||||||||||
17 | Test the automatic transmission wiring harness assembly for a short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find a condition? | -- | Go to Step 19 | -- | ||||||||||
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 automatic transmission wiring harness assembly. Refer to Valve Body and Pressure Switch Replacement . 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? | -- | Go to Step 21 | Go to Step 2 | ||||||||||
21 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 6.0L | System OK |
