DTC P1860 TCC PWM Solenoid Circuit Electrical Gas LQ4
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 CKT 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 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 D 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 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
| • | The PCM illuminates the malfunction indicator lamp for California emission vehicles. |
| • | The PCM inhibits TCC engagement. |
| • | The PCM inhibits 4th gear. |
| • | The PCM freezes shift adapts from being updated. |
| • | 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
| • | Inspect the wiring at the PCM, the transmission connector and all other circuit connecting points for the following conditions: |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Reduced terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| - | Moisture intrusion |
| - | Corrosion |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
| • | First diagnose and clear any engine DTCs or TP sensor codes that are present. Then inspect for any transmission DTCs that may have reset. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
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 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||
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. Is the fuse open? | -- | ||||||||
3 | Inspect the following components for a short to ground.
Refer to General Electrical Diagnosis in Wiring Systems. Was the condition corrected? | -- | Go to Diagnostic Aids | |||||||
Is the test lamp ON? | -- | |||||||||
5 | Repair the open or high resistance in ignition voltage feed CKT 1020 (PNK) to the TCC PWM solenoid valve. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||||
Does the test lamp turn ON when you command the TCC PWM solenoid valve ON, and does the lamp turn OFF when you command the TCC PWM solenoid valve OFF? | -- | |||||||||
7 |
Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | ||||||||
Is the resistance within the specified range? | 10-15ohms | |||||||||
9 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |||||||
10 |
Is the resistance within the specified range? | 10-15ohms | ||||||||
11 |
Are both readings greater than the specified value? | 250kohms | Go to Diagnostic Aids | |||||||
12 | Inspect the A/T wiring harness assembly for an open circuit. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | -- | |||||||
13 |
Are both readings greater than the specified value? | 250kohms | ||||||||
14 | Inspect the automatic transmission wiring harness assembly for a short to ground. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | -- | |||||||
15 | Replace the TCC PWM solenoid valve. Refer to Control Valve Body Replacement . Is the replacement complete? | -- | -- | |||||||
16 | Replace the automatic transmission wiring harness assembly. Refer to Wiring Harness Replacement. Is the replacement complete? | -- | -- | |||||||
17 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK |
