68RFE Automatic Transmission

P0890-SWITCHED BATTERY





For a complete wiring diagram refer to Diagrams/Electrical. Electrical Diagrams


Theory of Operation


The Totally Integrated Control Module (TIPM) replaces the Transmission control relay. The Transmission Control Output circuit is used to supply power to the solenoids and pressure switches (Transmission Solenoid/TRS Assembly) when the transmission is in normal operating mode. When the Transmission Control Output circuit is off, no power is supplied and the transmission.


Immediately after a controller reset (ignition key turned to the "run" position or after cranking engine), the PCM verifies that the Transmission Control Output circuits are open by checking for no voltage at the transmission control output terminals at the PCM. After this is verified, the voltage at the pressure switches are checked. There should be no voltage on the pressure switches at this time.


- When Monitored:

When the ignition is turned from "OFF" position to "RUN" position and/or the ignition is turned from "START" position to "RUN" position.

- Set Condition:

This DTC is set if the Powertrain Control Module (PCM) senses voltage on any of the pressure switch inputs prior to the Transmission Control Output circuit being energized.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. 68RFE Pre-Diagnostic Troubleshooting Procedure



Diagnostic Test


1. CHECK FOR RELATED DTCS

With the scan tool, check DTCs.

Are there any TIPM TCM Power Control Circuit and/or TCM Power Input DTCs present?

Yes

- Refer to the Transmission category and perform the appropriate symptom.

No

- Go To 2



2. CHECK TO SEE IF DTC P0890 IS PRESENT

With the scan tool, Check the STARTS SINCE SET counter for P0890.


NOTE: This counter only applies to the last DTC set.

Is the "Starts Since Set" counter set at 0?

Yes

- Go To 3

No

- Go To 5



3. CHECK THE PRESSURE SIGNAL CIRCUITS FOR A SHORT TO VOLTAGE





Turn the ignition off to the lock position.

Disconnect the PCM C4 harness connector and connect Miller tool #8815.

Disconnect the Transmission Solenoid/TRS Assembly harness connector.


CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller tool #8815 to perform diagnosis.

Ignition on, engine not running.

With the scan tool under TIPM, actuate the Transmission.

Measure the voltage of the (T147) 2C, (T48) 4C, (T50) L/R, (T9) OD, and (T29) UD Pressure Signal circuits.

Is the voltage above 0.5 volts on any of the measured circuits?

Yes

- Repair the (T147) 2C, (T48) 4C, (T50) L/R, (T9) OD, and/or (T29) UD Pressure Signal circuit(s) for a short to voltage.
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test

No

- Go To 4



4. CHECK THE TRANSMISSION SOLENOID/TRS ASSEMBLY





With the scan tool under TIPM, stop the Transmission actuation.

Turn the ignition off to the lock position.

Reconnect the Transmission Solenoid/TRS Assembly harness connector.

Ignition on, engine not running.

Measure the voltage of the (T147) 2C, (T48) 4C, (T50) L/R, (T9) OD, and (T29) UD Pressure Signal circuits.

Is the voltage above 0.5 volts on any of the measured circuits?

Yes

- Replace the Transmission Solenoid/TRS Assembly.
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test

No

- Using the schematics as a guide, check the Powertrain Control Module (PCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the PCM. With the scan tool, perform QUICK LEARN.
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test



5. CHECK THE WIRING AND CONNECTORS

The conditions necessary to set this DTC are not present at this time.

Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.

Wiggle the wires while checking for shorted and open circuits.

With the scan tool, check the DTC EVENT DATA to help identify the conditions in which the DTC was set.

Where there any problems found?

Yes

- Repair as necessary.
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test

No

- Test Complete.