Circuit/System Testing

Verify that none of the following conditions exist:
- Vacuum leaks or restrictions at the MAP sensor.
- Engine vacuum leaks
- Restricted exhaust-Refer to Restricted Exhaust .
- Worn piston rings-Refer to Engine Compression Test .
- Incorrect cam timing-Refer to Timing Belt Inspection .
Ignition OFF, disconnect the harness connector of the throttle body assembly.
Ignition ON, test for less than 0.2 volt between the low reference circuit of the TP sensor and ground.
- If greater than the specified value, test the low reference circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit of the TP sensor and ground.
- If greater than specified value, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.

IMPORTANT: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components.

Ignition ON, load test for 4.8-5.2 volts between the 5-volt reference circuit of the TP sensor and ground.
- If less than the specified range, test the 5-volt reference circuit of the TP sensor for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM.
- If greater than the specified range, test the 5-volt reference circuit of the TP sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.
Ignition ON, verify that the scan tool TP sensor voltage parameter is less than 0.3 volt.
- If greater than the specified value, test the signal circuit of the TP sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.
Install a 3-amp fused jumper wire between the signal circuit and the 5-volt reference circuit of the TP sensor. Verify that the scan tool TP sensor voltage parameter is greater than 4.8 volts.
- If less than the specified value, test the signal circuit of the TP sensor for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.
Ignition OFF, connect the harness connector of the throttle body assembly.
Disconnect the harness connector of the MAP sensor.
Ignition ON, test for less than 0.2 volt between the low reference circuit of the MAP sensor and ground.
- If greater than the specified value, test the low reference circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit of the MAP sensor and ground.
- If greater than specified value, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.
Ignition ON, verify that the MAP sensor parameter is less than 12 kPa.
- If greater than 12 kPa, test the signal circuit of the MAP sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.

Load test for 4.8-5.2 volts between the 5-volt reference circuit of the MAP sensor and ground.
- If less than the specified range, test the 5-volt reference circuit of the MAP sensor for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM.
- If greater than the specified range, test the 5-volt reference circuit of the MAP sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.
Ignition ON, install a 3-amp fused jumper wire between the signal circuit and the 5-volt reference circuit of the MAP sensor. Verify that the scan tool MAP sensor pressure parameter is greater than 102 kPa.
- If less than the specified value, test the signal circuit of the MAP sensor for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.
If all circuits/connections test normal, test or replace the MAP sensor.