4L80-E / 4L85-E Automatic Transmission

DTC P0706

Circuit Description with 4L80-E / 4L85-E Automatic Transmission
The transmission range (TR) switch is part of the park/neutral position and back-up lamp switch assembly and is externally mounted on the transmission manual shaft. The TR switch is a multi-signal switch. The powertrain control module (PCM) supplies ignition voltage to the TR switch on four signal circuits, A, B, C. and P. Each gear selector lever position grounds one or more of the switch circuits. In order to determine the gear range selected by the driver, the PCM compares the voltage combinations on the signal circuits to a look up table stored in the PCM memory. PCM detects the selected gear range by the state change of the switch input.

Switch input to the PCM is represented on the scarf tool as HI and Low. HI indicates an ignition voltage signal. Low indicates a zero voltage signal. The four parameters represent transmission range switch signal A, B, C and Parity.

DTC P0706 sets if the PCM detects vehicle speed in PARK or NEUTRAL range. DTC P0706 is a type C DTC.

Conditions for Running the DTC.
^ No TPS DTCs P0121, P0122 or P0123
^ No VSS DTCs P0502 or P0503.
^ No incorrect gear ratio DTC P0730.
^ Ignition voltage is 6-18 volts.
^ The engine is running for greater than 60 seconds.
^ The commanded gear is 3rd or 4th.
^ The throttle angle is 5 percent or greater.
^ The engine torque is greater than 68 Nm (50 ft. lbs.).
^ The vehicle speed is 32 km/h (20 mph) or greater.
^ The PTO mode is not active.

Conditions for Setting the DTC
The Conditions for Running the DTC are met and the PCM detects PARK or NEUTRAL.

Action Taken When the DTC Sets
^ The PCM will use TFP Switch to determine gear range.
^ The PCM does not illuminate the malfunction indicator lamp (MIL).
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
^ The PCM stores DTC P0706 in PCM history.

Conditions for Clearing the DTC
^ A scan tool can clear the DTC.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
5. By disconnecting the transmission range switch, the ground path of all TR switch circuits would be removed and the PCM would recognize all circuits as open. The scan tool will display HI for all range signals.
6. This step tests TR switch wiring for an open or the lack of the signal voltage from the PCM.
7. This step tests TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal A should change to LOW.
8. This step tests TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal B should change to LOW.
9. This step tests TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal C should change to LOW.

Steps 1 - 2:

Steps 3 - 10:

Steps 11 - 17:

DTC P0706