P0705

DTC P0705 Transmission Range Switch Circuit




Circuit Description
The Transmission Range Switch, which is part of the Park/Neutral Position (PNP), is a multi-signal switch which sends a signal to the PCM to indicate gear selection. The Transmission Range Switch uses 4 discrete circuits to pull 4 PCM voltages low in various combinations to indicate each gear range. The voltage level of the circuits is represented as LO = grounded, HI = open circuit. The 4 states displayed represents the encoder P, A, B, and C inputs in sequence.

Conditions for Running the DTC
- The PCM recognizes an invalid PRNDL parameter.
- The vehicle speed is more than 5 mph (8 kph).

Conditions for Setting the DTC
The above conditions met for a period of more than 5 seconds.

Action Taken When the DTC Sets
- The PCM will record operating conditions at the time during which the diagnostic fails. This information will store in the Failure Records buffer.
- A history DTC stores.

Conditions for Clearing the MIL/DTC
- A history DTC will clear after 40 consecutive warm up cycles without a fault.
- A scan tool can clear the MIL/DTCs.

Diagnostic Aids
- Monitor a scan tool while moving the related connectors and the wiring harness. If a failure is induced, the scan data will change states from either LO to HI, or from HI to LO. Move the gear selector slowly through each gear while monitoring the scan tool in order to help isolate the problem.
- When a DTC P0705 sets, the PCM defaults to the 3rd gear until the PCM receives a correct combination. Therefore, some of the selected gear positions may not be possible until you repair the fault.
- If the trans range switch on the scan tool and the PRNDL on the IPC display a normal reading only in the following gear selections:
- Park, Low, and 2nd gear -check for an open in the TR switch input B circuit
- Reverse, Neutral, Overdrive and 3rd gear -check for a grounded TR switch input B circuit.
- Low, 2nd, 3rd and Overdrive gear -check for a grounded in the TR switch input C circuit.
- Park, Reverse, and Neutral -check for an open in the TR switch input C circuit.
- Park, Reverse, 2nd and 3rd gear -check for a grounded in the TR switch input A circuit.
- Neutral, Overdrive and Low gear -check for an open in the TR switch input A circuit.
- Park, Neutral, 3rd and Low gear -check for a grounded in the TR switch input P circuit.
- Reverse 2nd and Overdrive gear -check for an open in the TR switch input P circuit.




An intermittent may be caused by any of the following conditions:
- A poor connection
- Rubbed through wire insulation
- A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent and Poor Connections.

If a repair is necessary, refer to Wiring Repairs or Connector Repairs.

Steps 1 - 2:

Steps 3 - 6:

Steps 7 - 11:

Test Description
The numbers below refers to the step numbers on the Diagnostic Table.
1. The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when this DTC set. The scan tool stores this data for later reference.
4. Thoroughly check any suspected circuitry for the following conditions:
- Backed out terminals
- Improper mating
- Broken locks
- Improperly formed or damaged terminals
- Poor terminal to wiring connections
- Physical damage to the wiring harness
5. An invalid circuit will cause the PRNDL display to go out. Connecting a Jumper wire to each circuit to ground simulates the Park/Neutral Position switch operation, and checks the circuitry and the PCM. While the trans range switch is disconnected and the circuits are not jumpered to ground, the scan tool should indicate a HI value. A value that is indicated as LO with no jumper to ground indicates a grounded circuit or a malfunctioning PCM.
9. Program the replacement PCM and perform the crankshaft position system variation learn procedure. Refer to the latest Isuzu Technical Communications System (ITCS) procedures for PCM programming.
11. If no malfunctions are present at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.