For 1990-2009 cars
Engine Controls Components
IAC Valve, PNP, and Ignition Switch
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The PCM supplies ignition voltage to the Park/Neutral position switch through the signal circuit. The contacts inside the switch open whenever the voltage is greater than 1 V. The Park Neutral position switch contacts should remain closed whenever the transaxle is in park or neutral. The contacts will open whenever in the Drive and Reverse ranges.

### Conditions for Setting the DTC

• | Engine Speed is between 1700 and 3000 RPM.

• | TP Sensor is between 7 and 20 %.

• | Vehicle speed is greater than 40 MPH.

• | One or more of the following DTCs are not set P0121, P0122, P0123, P0335, P0502, or P0503

### Action Taken When the DTC Sets

• | The Malfunction Indicator Lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the fault active.

• | The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.

• | A history DTC is stored.

### Conditions for Clearing the MIL/DTC

• | The MIL will turn OFF after three 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.

• | The MIL/DTCs can be cleared by using the scan tool.

### Diagnostic Aids

• | An intermittent problem may be caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.

• | Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for the following conditions:

- | Backed out terminals

- | Improper mating of the terminals

- | Broken locks

- | Improperly formed or damaged terminals

- | Poor terminal to wiring connections

- | Physical damage to the wiring harness

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The 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 fault occurred. This information on the scan tool can be referred to later

2. Before replacing the PCM, check terminals for improper mating, broken locks, or physical damage to the wiring harness. Replacement PCM's must be reprogrammed. Refer to the latest Techline information for programming procedures.

#### DTC P1520 Park Neutral Position (PNP) Discrete

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Shift the transaxle into Park.
2. Install a scan tool.

Does the scan tool read the specified value

P-N

Go to Step 3

Go to Step 5

3 | Shift the transaxle into Drive. Does the scan tool read the specified value? | R-D-L | System OK, refer to Diagnostic Aids | Go to Step 4
4 | Disconnect the PNP switch. Does the scan tool read the specified value | R-D-L | Go to Step 11 | Go to Step 9
5 |

1. Disconnect the PNP switch electrical connector.
2. Use a fused jumper and jumper terminal A to the ground circuit at the harness.

Does the scan tool read the specified value?.

P-N

Go to Step 11

Go to Step 6

6 | Use a fused jumper to jumper the PNP switch input circuit to an external ground. Does the scan tool read the specified value? | P-N | Go to Step 7 | Go to Step 8
7 | Repair the open ground circuit. Is the action complete? | -- | Go to Step 13 | --
8 | Check the PNP switch input circuit for an open or short and repair if necessary. Was a problem found? | -- | Go to Step 13 | Go to Step 10
9 | Check the PNP switch input circuit for a short to ground and repair if necessary. Was a problem found? | -- | Go to Step 13 | Go to Step 10
10 | Replace the PCM. Is the action complete? | -- | Go to Step 13 | --
11 | Check the adjustment on the PNP switch and adjust if necessary. Was a problem found? | -- | Go to Step 13 | Go to Step 12
12 | Replace the PNP switch. Is the action complete? | -- | Go to Step 13 | --
13 |

1. Using the scan tool, clear DTCs
2. Start the engine.
3. Allow the engine to idle until the engins rreaches the specified temperature.
4. Operate the vehicle within the conditions for setting this DTC as supported in the text.

Does the scan tool indicate that this diagnostic ran and passed?

90°-95°C

Go to Step 14

Go to Step 2

14 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to Applicable DTC Table | System OK