Circuit Description
The TCC release switch is part of the transmission fluid pressure (TFP) manual valve position switch. The TFP manual valve position switch is mounted to the transmission valve body. The TCC release switch is normally-closed.
The switch signals the PCM that the TCC is released. This is accomplished by torque converter release fluid pressure acting on the switch contact which opens the circuit. When the circuit voltage is high, the PCM recognizes that the TCC is no longer engaged.
If the PCM determines that the TCC release switch is open (indicating that the TCC is not applied) and the TCC slip speed indicates that the TCC is applied, then DTC P1887 sets. DTC P1887 is a type B DTC.
Conditions for Running the DTC
| • | No AT ISS sensor DTC P0716 or P0717. |
| • | No TCC PWM solenoid valve DTC P0741 or P0742. |
| • | No TFP manual valve position switch DTC P1810. |
| • | The engine speed is greater than 500 RPM for 5 seconds and not in fuel shut off. |
| • | The transmission range selector is in D4. |
| • | The TCC is commanded ON. |
| • | The TCC pressure is 138-827 kPa (20-120 psi). |
| • | The TCC slip speed is -20 to +60 RPM. |
| • | The engine torque is 41-339 N·m (30-250 lb ft). |
Conditions for Setting the DTC
DTC P1887 sets when the following condition occurs twice in a single trip:
The TCC release pressure switch is open (indicating release pressure present) for 6 seconds continuous.
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. |
| • | The PCM inhibits 4th gear if the transmission is in Hot Mode. |
| • | The PCM freezes shift adapts. |
| • | 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 P1887 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 the PCM history if the vehicle completes 40 consecutive warm-up cycles without an 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 connectors at the controller, the component and all other circuit connecting points for an intermittent condition. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | Inspect the circuit wiring for an intermittent condition. Refer to Testing for Electrical Intermittents in Wiring Systems. |
| • | Ensure the wiring harness is not stretched too tightly or other components are pressing on the A/T inline 20-way connector body. Also inspect for proper clearance to any other components and wiring. Refer to Intermittent Conditions in Engine Controls - 3.4L. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the PCMs ability to recognize a grounded circuit.
-
A short to ground in this circuit would set DTC P0742.
-
A short to ground in this circuit would set DTC P0742.
Step | Action | Value(s) | Yes | No | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain Diagnostic System Check? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls | |||||||||||||
2 |
Important: Before clearing the DTCs, use the Scan Tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear Info function will erase the stored Freeze Frame and Failure Records from the PCM. Does the Scan Tool indicate that TCC release pressure is present? | -- | ||||||||||||||
Refer to Automatic Transmission Inline Harness Connector End View . Does the Scan Tool indicate that TCC release pressure is present? | -- | |||||||||||||||
Test the signal circuit (CKT 657) of the TCC release switch for an open between the PCM connector and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | -- | |||||||||||||||
Test the signal circuit (CKT 1804) of the TCC release switch for an open between the AT inline 20-way connector and the TFP manual valve position switch. Refer to the following:
Did you find a condition? | -- | |||||||||||||||
6 |
Does the Scan Tool indicate that TCC release pressure is present? | -- | Go to Diagnostic Aids | |||||||||||||
7 | Inspect the following mechanical components and hydraulic circuits that could cause TCC release pressure at the TCC release switch when the TCC is applied:
Refer to Transmission Overhaul in the 4T65-E Section of the Transmission Unit Repair Manual. Did you complete the repair? | -- | -- | |||||||||||||
8 | Replace the AT wiring harness assembly. Refer to Wiring Harness Replacement . Did you complete the replacement? | -- | -- | |||||||||||||
9 | Replace the TFP manual valve position switch. Refer to Transmission Fluid Pressure Manual Valve Position Switch Replacement . Did you complete the replacement? | -- | -- | |||||||||||||
10 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Did you complete the replacement? | -- | -- | |||||||||||||
11 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK |
