P0890-SWITCHED BATTERY





For a complete wiring diagram Refer to Section 8W.

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


Possible Causes
  
PRESSURE SWITCH SENSE CIRCUITS SHORT TO VOLTAGE
  
TRANSMISSION SOLENOID/TRS ASSEMBLY
  
TRANSMISSION CONTROL MODULE
  

Always perform the 45RFE/545RFE Pre-Diagnostic Troubleshooting Procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)



Diagnostic Test

1.CHECK TO SEE IF DTC P0890 IS PRESENT


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



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

Yes
  • Go To 2


No
  • Go To 4

2.PRESSURE SWITCH SENSE CIRCUITS SHORT TO VOLTAGE











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

Yes


No
  • Go To 3

3.TRANSMISSION SOLENOID/TRS ASSEMBLY





NOTE: Do not reinstall the Transmission Relay.






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

Yes


No
  • Using the schematics as a guide, check the Transmission Control Module (TCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the TCM per the Service Information. With the scan tool, perform QUICK LEARN.
  • Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

4.INTERMITTENT WIRING AND CONNECTORS






Where there any problems found?

Yes


No
  • Test Complete.