For 1990-2009 cars
Engine Controls Schematics

### Circuit Description

The test switch terminal is located in the duty check data link connector behind the glovebox. The PCM fixes the ignition timing to the base setting when the test switch terminal is grounded.

### Condition for Running the DTC

Engine operating in Close Loop.

### Conditions for Setting the DTC

• | Vehicle speed is greater than 2 km/h (1 mph).

• | The test switch is ON (circuit is grounded).

• | The condition is present for 5 seconds

### Action Taken When the DTC Sets

• | The PCM illuminates the malfunction indicator lamp (MIL).

• | The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

### Conditions for Clearing the MIL/DTC

• | The PCM turns OFF the MIL after three consecutively passing trips without a fault present.

• | A History DTC clears after 40 consecutive warm-up cycles without a fault.

• | Use the scan tool Clear DTC Information function in order to clear the DTC information.

### Diagnostic Aids

Check for a damaged wiring harness. Inspect the wiring harness for damage that may cause a short to ground. With the engine running, wiggle the wiring harness to the duty check data link connector while monitoring the Spark Advance Adjust Test Switch parameter on a scan tool for an ON display, indicating that the harness is shorting to ground.

### Test Description

The numbers below refer to the step numbers in the Diagnostic Table.

1. The Powertrain (OBD) System Check prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. This step determines if fault is present.

3. This step checks for a short to ground on the test switch terminal and its circuitry. When there is a short to ground the ignition timing will be fixed at the base timing specification.

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

1. Install a scan tool.
2. Perform the scan tool clear DTC information function.
3. Start the engine.
4. Observe the Spark Adv. Adj. Test Switch parameter on the scan tool.

Does the Spark Adv. Adj. Test Switch parameter on the scan tool indicate ON?

--

Go to Step 3

Fault not Present-Go to Diagnostic Aids

3 |

1. Turn ON the ignition, leaving the engine OFF.
2. Measure the voltage from the test switch signal circuit at terminal 5 (PPL/GRN wire) of the duty check data link connector, with a DMM.

Is the voltage near the specified value?

5 volts

Go to Diagnostic Aids

Go to Step 4

4 |

1. Check the test switch signal circuit, PPL/GRN wire, for a short to ground.
2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 6

Go to Step 5

5 | Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | Go to Step 6 | --
6 |

1. Review the scan tool data and check for DTCs.
2. The repair is complete if no DTCs are stored.

Are any DTCs displayed on the scan tool?

--

Go to the Applicable DTC Table

System OK