P0890

P0890-SWITCHED BATTERY





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Transmission control relay 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 relay is off, no power is supplied and the transmission is in "limp-in" mode. The relay output is fed back to the PCM through pins C4-19, C4-28 and C4-38 and are referred to as "Transmission Control Relay Output".

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

- 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 senses voltage on any of the pressure switch inputs prior to the Transmission Control Relay being energized.





Always perform the Pre-Diagnostic Troubleshooting Procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. CHECK IF THE DTC IS CURRENT
1. With the scan tool, read DTCs.

Is the status Active or is the Starts Since Set counter 0 for this DTC?

Yes

- Go To 2

No

- Go To 4

2. PRESSURE SIGNAL CIRCUITS SHORTED TO VOLTAGE




1. Turn the ignition off to the lock position.
2. Disconnect the PCM C4 harness connector and connect the PCM Pinout Box 8815.
3. Disconnect the Transmission Solenoid/TRS Assembly harness connector.
4. Remove the Transmission Control Relay.

NOTE: Note: Check connectors - Clean/repair as necessary.

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 the PCM Pinout Box 8815 to perform diagnosis.

5. Connect a jumper wire between the Fused B(+) circuit and the Transmission Control Output circuit in the Transmission Control Relay connector.
6. Ignition on, engine not running.
7. Measure the voltage of the (T147) 2C, (T48) 4C, (T50) L/R, (T9) OD, and (T29) UD Pressure Signal circuits in the PCM Pinout Box 8815.

Is the voltage above 0.5 of a volt 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 the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Go To 3

3. TRANSMISSION SOLENOID/TRS ASSEMBLY




1. Turn the ignition off to the lock position.
2. Remove the jumper wire.

NOTE: Do not reinstall the Transmission Relay.

3. Reconnect the Transmission Solenoid/TRS Assembly harness connector.
4. Ignition on, engine not running.
5. Measure the voltage of the (T147) 2C, (T48) 4C, (T50) L/R, (T9) OD, and (T29) UD Pressure Signal circuits in the PCM Pinout Box 8815.

Is the voltage above 0.5 of a volts on any of the sense circuits?

Yes

- Replace the Transmission Solenoid/TRS Assembly.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE 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 and program the PCM. With the scan tool, perform Quick Learn. Quick Learn Procedure
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

4. CHECK THE WIRING AND CONNECTORS
1. The conditions necessary to set this DTC are not present at this time.
2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Wiggle the wires while checking for shorted and open circuits.
4. With the scan tool, check the Event Data to help identify the conditions in which the DTC was set.

Where there any problems found?

Yes

- Repair as necessary.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Test Complete.