Circuit Description
The PCM supplies ignition voltage to the Park/Neutral Position(PNP) switch through the signal circuit. The contacts inside the switch open whenever the voltage is greater than 1 V. The Transmission Range position (TR) switch contacts should remain closed whenever the transmission is in park or neutral. The contacts will open whenever in the drive and reverse ranges.
Conditions for Setting the DTC
| • | The Engine Speed is between 1600 and 2800 RPM. |
| • | The TP Sensor is between 7 and 26%. |
| • | The vehicle speed is greater than 40 MPH. |
| • | The PNP switch shows P/N without change since startup. |
| • | One or more of the following DTCs are not set P0121, P0122, P0123, P0335, P0502, or P0503. |
or
| • | The PNP switch shows P/N regardless of range selected. |
| • | The above condition is present for 27 seconds. |
Action Taken When the DTC Sets
| • | The Malfunction Indicator Lamp (MIL) illuminates after 2 consecutive ignition cycles in which the diagnostic runs with the fault active. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The Freeze Frame and Failure Records buffers stores this information. |
| • | A history DTC is stored. |
Conditions for Clearing the MIL/DTC
| • | The malfunction indicator lamp (MIL) will turn OFF after 3 consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm up cycles without a fault. |
| • | Use a scan tool to clear the DTCs. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The Powertrain OBD System Check prompts the Technician to complete some basic checks and store the Freeze Frame Data and the Failure Records on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurs. Refer to this information on the scan tool later.
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Before replacing the PCM, check the terminals for improper mating, broken locks, or physical damage to the wiring harness. Replacement PCMs must be reprogrammed and the crankshaft position system variation procedure must be performed. Refer to the latest Isuzu Technical Communication System (ITCS) information for programming procedures and also refer to the Powertrain Control Module (PCM) .
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||
2 |
Does the scan tool display P/N? | -- | ||
3 | Shift the transmission into Drive. Does the scan tool display R/DL? | -- | System OK | |
4 | Disconnect the Park Neutral Position (PNP) switch. Does the scan tool display R/DL? | -- | ||
5 |
Does the scan tool display P/N? | -- | ||
6 | Use a fused jumper in order to jumper the PNP switch B+ feed circuit to a ground on the harness. Does the scan tool display R/DL? | -- | ||
7 | Repair the open in the ground circuit. Is the action complete? | -- | -- | |
8 |
Was a problem found? | -- | ||
9 |
Was a problem found? | -- | ||
Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||
11 |
Was a problem found? | -- | ||
12 | Replace the Park Neutral Position (PNP) switch. Refer to Transmissions. Is the action complete? | -- | -- | |
13 |
Does the scan tool indicate that this diagnostic ran and passed? | 90°-95°C | ||
14 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to the Applicable DTC Table | System OK |
