P0890

P0890-SWITCHED BATTERY

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

Theory of Operation

The transmission relay is used to supply power to the solenoid pack when in normal operating mode, and to turn off power to produce transmission "limp-in" mode. The relay output (which supplies power to the solenoid pack) is fed back to the controller. It is referred to as SWITCHED BATTERY. After a controller reset (ignition key turned to the RUN position or after cranking engine), the controller verifies that the relay contacts are open by checking for no voltage on Switched battery line (i.e. transmission control relay output) before the relay is energized. After switched battery is verified for no voltage, the voltage of each of the solenoid pack pressure switches is also checked. Since the solenoid pack is not powered up, there should be no voltage on any of the pressure switches.

- When Monitored:

One time after a reset (ignition key turned to the RUN position or after cranking engine).

- Set Condition:

Fault Set If: A voltage is greater than 4.5 volts is detected on any of the pressure switches, before the relay is energized. Fault Set Time: Less than 7 msec, transmission placed in Limp-In. MIL on after 10 sec. of vehicle operation.

Always perform the 42RLE Pre-Diagnostic Troubleshooting Procedure before proceeding. 42RLE - Pre-Diagnostic Troubleshooting Procedure

Diagnostic Test

1. 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 2

No

- Go To 5

2. (T9) OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE

Turn the ignition off to the lock position.

Disconnect the PCM C4 harness connector.

Disconnect the Solenoid/Pressure Switch Assembly harness connector.

Remove the Transmission Control Relay.

NOTE: Check connectors - Clean/repair as necessary.

Connect a jumper wire between the (Internal) Fused B+ circuit and (T16) Transmission Control Relay Output circuit in the Transmission Control Relay connector.

Ignition on, engine not running.

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 Special Tool #8815 to perform diagnosis.

Measure the voltage of the (T9) OD Pressure Switch Sense circuit.

Is the voltage above 0.5 volt?

Yes

- Repair the (T9) OD Pressure Switch Sense circuit for a short to voltage.
- Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests

No

- Go To 3

3. (T47) 2/4 PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE

Turn the ignition off to the lock position.

Disconnect the PCM C4 harness connector.

Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.

Remove the Transmission Control Relay.

NOTE: Check connectors - Clean/repair as necessary.

Connect a jumper wire between the (Internal) Fused B+ circuit and (T16) Transmission Control Relay Output circuit in the Transmission Control Relay connector.

Ignition on, engine not running.

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 Special Tool #8815 to perform diagnosis.

Measure the voltage of the (T50) L/R Pressure Switch Sense circuit.

Is the voltage above 0.5 volts?

Yes

- Repair the (T50) L/R Pressure Switch Sense circuit for a short to voltage.
- Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. 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 the PCM. With the scan tool PERFORM QUICK LEARN, then program Pinion Factor in the Front Control Module.
- Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests

5. INTERMITTENT WIRING AND CONNECTORS

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

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

Wiggle the wiring and connectors while checking for shorted and open circuits.

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

Were there any problems found?

Yes

- Repair as necessary.
- Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests

No

- Test Complete.