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 C1-26, C1-27 and C1-28 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 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 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 (PCM) 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.
Diagnostic Test
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.
2. Turn the ignition OFF.
3. Disconnect the PCM C1 harness connector.
4. Disconnect the Transmission Solenoid/TRS Assembly harness connector.
5. Connect a fused jumper wire or a 12-volt test light connected to 12-volts to the T15 Transmission Control circuit on the appropriate terminal of the PCM C1 harness connector to actuate the internal TCM relay in the PDC.
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
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 the TRANSMISSION VERIFICATION TEST. Verification Tests.
No
- Go To 3
3. TRANSMISSION SOLENOID/TRS ASSEMBLY
1. Turn the ignition OFF.
2. Remove the jumper wire or 12-volt test light from the T15 Transmission Control circuit in the PCM C1 harness connector.
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
Is the voltage above 0.5 volts on any of the sense circuits?
Yes
- Replace the Transmission Solenoid/TRS Assembly. Transmission Solenoid And TRS Assembly - Removal.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.
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 a Quick Learn. Powertrain Control Module - Removal.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.
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 set.
Where any problems found?
Yes
- Repair as necessary.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.
No
- Test Complete.