DTC P0708: TRANSMISSION RANGE SENSOR CIRCUIT HIGH INPUT Chevrolet Silverado 2500

Note. For circuit identification, see CONNECTOR IDENTIFICATION and WIRING DIAGRAMS .

Circuit Description

The Park/Neutral Position (PNP) switch mounts directly onto the transmission housing from the outside, and detects the angular position of the selector shaft. This position is communicated to the Transmission Control Module (TCM) so that certain vehicle control functions can be coordinated with the position of the shift controls. The PNP switch has redundant circuitry to alert the TCM in the event of a single wire or switch failure.

The Neutral signal output of the PNP switch is typically used as confirmation that the transmission is in Neutral before the engine starter is engaged. The PNP switch is interfaced to the starter circuit with weatherproof electrical connectors. The Reverse signal provision may be used to activate vehicle back-up lights and/or Reverse warning devices.

This is a type "A" DTC.

Conditions For Running The DTC

DTC will run under the following conditions

1. The components are powered, and ignition voltage is greater than 9 volts and less than 18 volts.
2. Engine speed is greater than 200 RPM and less than 7500 RPM for 5 seconds.

Conditions For Setting The DTC

DTC will set under the following condition

1. DTC sets when the TCM detects an invalid condition and parity errors occurring over consecutive ignition cycles.

Action Taken When The DTC Sets

TCM performs the following actions if DTC is set

1. While diagnostic response is active, one of the following conditions can occur: If the gearshift lever is moved to Neutral, then the transmission will shift to Neutral. If the gearshift lever is moved to Reverse, then the transmission will shift to Reverse. If the gearshift lever is moved to a forward gear range, then the transmission will shift to 3rd or 5th gear unless the transmission is compromised by overspeeding or direction change (then the transmission will shift to Neutral).
2. DTC will be stored in the TCM history.
3. The TCM freezes shift adapts.
4. Illuminates the MIL when active.
5. Due to this failure and associated response, DTC P0722 and DTC P0845 also set.
6. TCM inhibits TCC engagement.

Conditions For Clearing The DTC

DTC will clear under the following conditions

1. A scan tool can clear the DTC from the TCM history.
2. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without failure.

Test Description

The numbers listed below refer to step numbers in the diagnostic procedure

1. 3 This step tests PNP switch status.
2. 4 This step tests TCM input response.
3. 5 This step tests the wiring harness for open or short.