P0957

P0957-AUTOSTICK CIRCUIT LOW (ERS)





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


Theory of Operation


Electronic Range Select (ERS) is an electronic gear selector. In ERS mode the transmission will upshift and downshift normally only up to the selected gear.


The AutoStick(R) (ERS) Tow/Haul Overdrive Off switch uses a MUX (multiplex) switch. The PCM monitors the AutoStick(R) (ERS) Tow/Haul Signal circuit for voltage changes in respect to the position of the switch. If the PCM detects an improper voltage during upshift, downshift, or in its neutral state, a DTC will set.


- When Monitored:

Whenever the engine is running.

- Set Condition:

The PCM detects a voltage below 0.35 volts for the period of 5.0 seconds on the AutoStick(R) (ERS) Tow/Haul Signal circuit.







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



Diagnostic Test


1. CHECK IF THE DTC IS CURRENT

With the scan tool, check the STARTS SINCE SET counter for P0957.


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

Is the Starts Since Set counter set at 2 or less?

Yes

- Go To 2

No

- Go to5



2. CHECK THE AUTOSTICK(R) (ERS) TOW/HAUL SIGNAL CIRCUIT






With the scan tool, monitor the AutoStick voltage in the following steps:

With the ignition on, engine not running and the vehicle in drive, using the AutoStick (ERS) Tow/Haul Overdrive Off switch, switch to all shift positions while noting the scan tool values and voltages.

Pick one of the following that best describes your findings

Voltage is below 0.35 volts in ALL four switch positions and no values change

- Go to 3

Voltage is below 0.35 volts in ONE of four switch positions

- Go to4

All shift values and voltages are within limits

- Go to5



3. CHECK THE (T5) AUTOSTICK(R) (ERS) TOW/HAUL SIGNAL CIRCUIT FOR A SHORT TO GROUND





Turn the ignition off to the lock position.

Disconnect the PCM C1 harness connector.

Disconnect the AutoStick(R) (ERS) Tow/Haul Overdrive Off Switch 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 Special Tool #8815 to perform diagnosis.

Measure the resistance between ground and the (T5) AutoStick(R) (ERS) Tow/Haul Signal circuit.

Is the resistance below 5.0 ohms?

Yes

- Repair the (T5) AutoStick(R) (ERS) Tow/Haul Signal circuit for a short to ground.
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test

No

- Go to4



4. CHECK THE AUTOSTICK(R) (ERS) TOW/HAUL OVERDRIVE OFF SWITCH










Measure the resistance of the AutoStick(R) (ERS) Tow/Haul Overdrive Off Switch between the (T5) AutoStick(R) (ERS) Tow/Haul Signal circuit and the Sensor Ground circuit in all three shift positions. Use the above chart to verify your findings.

Are the resistances of the AutoStick(R) (ERS) Tow/Haul Overdrive Off Switch within limits?

Yes

- 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. Check for Service Information Tune-ups or Service Bulletins for any possible causes that may apply. If no problems are found, replace and program the PCM. With the scan tool, perform QUICK LEARN.
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test

No

- Replace the AutoStick(R) (ERS) Tow/Haul Overdrive Off Switch.
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test



5. INTERMITTENT 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 EVENT DATA to help identify the conditions in which the DTC was set.


NOTE: It may be necessary to test drive the vehicle to enable or cause the DTC to set.

Check for any Service bulletins that may apply.

Were there any problems found?

Yes

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

No

- Test Complete.