Circuit Description
The Torque Converter Clutch Pulse Width Modulation Solenoid Valve (TCC PWM Solenoid Valve) controls fluid acting on the converter clutch valve, which then controls TCC apply and release. The TCC PWM Sol. Valve attaches to the control valve body within the transmission. Ignition voltage goes directly to the TCC PWM Sol. Valve. The Vehicle Control Modulator (VCM) controls the TCC PWM Sol. Valve by providing a ground path on circuit 418. The current flows through the TCC PWM Sol. Valve coil according to the duty cycle (percentage of ON time). The TCC PWM Sol. Valve provides a smooth engagement of the torque converter clutch by operating on a duty cycle percent of ON time.
If the VCM detects a continuous open or short in the TCC PWM Sol. Valve circuit or the TCC PWM Sol. 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 Setting the DTC
| • | The system voltage is 10-16.0 volts. |
| • | The engine is running greater than 475 RPM. |
| • | No shift solenoid DTCs P0751, P0753, P0756, or P0758. |
| • | Commanded gear is first. |
| • | All of the above conditions are met and either of the following conditions occur for 5 seconds. |
| - | The VCM commands the TCC PWM Sol. Valve to OFF (0%) and the voltage input remains low (zero volts). |
| - | The VCM commands the TCC PWM Sol. Valve to ON (100%) and the voltage input remains high (B+). |
Action Taken When the DTC Sets
| • | The VCM illuminates the Malfunction Indicator Lamp for California emission vehicles. |
| • | The VCM inhibits TCC engagement. |
| • | The VCM inhibits 4th gear. |
| • | The VCM freezes shift adapts from being updated. |
| • | DTC P1860 is stored in VCM history. |
Conditions for Clearing the DTC
| • | For California emissions vehicles, the VCM turns OFF the MIL after three consecutive trips without a failure reported. |
| • | A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported. |
| • | The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM. |
Diagnostic Aids
| • | Inspect the wiring at the VCM, the transmission connector and all other circuit connecting points for the following conditions: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor 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 Sol. Valve circuit at the 20-way connector.
-
This step tests the ability of the VCM and wiring to control the ground circuit.
-
This step tests the resistance of the TCC PWM Sol. 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 for reference. The Clear Info function will erase the stored Freeze Frame and Failure Records from the VCM. Is the fuse open? | -- | ||||||||
3 | Inspect the following components for a short to ground.
Refer to General Electrical Diagnosis in Wiring Systems. Did you find and correct the condition? | -- | Go to Diagnostic Aids | |||||||
Is the test lamp ON? | -- | |||||||||
5 | Repair the open or high resistance in ignition voltage feed circuit 1020 to the TCC PWM Sol. Valve. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||||
Does the test lamp turn ON when you command the TCC PWM Sol. Valve ON, and does the lamp turn OFF when you command the TCC PWM Sol. Valve OFF? | -- | |||||||||
7 |
Refer to General Electrical Diagnosis in Wiring Systems. Did you find the condition? | -- | ||||||||
Is the resistance within the specified values? | 10-15Ω | |||||||||
9 | Replace the VCM. Refer to VCM Replacement/Programming. Is the replacement complete? | -- | -- | |||||||
10 |
Is the resistance within the specified values? | 10-15Ω | ||||||||
11 |
Are both readings greater than the specified value? | 250kΩ | Go to Diagnostic Aids | |||||||
12 | Inspect the A/T Wiring Harness Assembly for an open circuit. Refer to General Electrical Diagnosis in Wiring Systems. Did you find the condition? | -- | -- | |||||||
13 |
Are both readings greater than the specified value? | 250kΩ | ||||||||
14 | Inspect the Automatic Transmission Wiring Harness Assembly for a short to ground. Refer to General Electrical Diagnosis in Wiring Systems. Did you find the condition? | -- | -- | |||||||
15 | Replace the TCC PWM Sol. Valve. Refer to Control Valve Body Removal and Disassembly, in On-Vehicle Service. Is the replacement Complete? | -- | -- | |||||||
16 | Replace the Automatic Transmission Wiring Harness Assembly. Refer to Internal Wiring Harness Replacement, in On-Vehicle Service. Is the replacement Complete? | -- | -- | |||||||
17 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
