Electronic Control System Gas Plus Engines – 019-354   Intake Manifold Absolute Pressure and Temperature Sensor Circuit

Disconnect engine harness ECM connector 1 from the ECM. Disconnect the intake manifold absolute pressure and temperature sensor from the engine harness. Disconnect the oil pressure/temperature sensor and the fuel pressure/temperature sensor from the engine harness.

Set the multimeter to measure resistance.

Measure the resistance from the intake manifold absolute pressure +5-VDC supply pin in engine harness ECM connector 1 to the corresponding pin in the sensor harness connector. Repeat the resistance check from the pressure signal pin in the ECM connector to the corresponding pin in the sensor harness connector.

The resistance checks
must show a multimeter reading of 10 ohms or less (closed circuit). If the circuit is
not closed, repair or replace the engine harness. Refer to Procedure
019-205,
019-204, or
019-043.

Measure the resistance from the temperature signal pin in the ECM connector to the corresponding pin in the sensor harness connector. Repeat the resistance check from the pressure/temperature return pin in the ECM connector to the corresponding pin in the sensor harness connector.

Both resistance checks
must show a multimeter reading of 10 ohms or less (closed circuit). If the circuit is
not closed, repair or replace the engine harness. Refer to Procedure
019-205,
019-204, or
019-043.

Disconnect engine harness ECM connector 1 from the ECM.

Disconnect the intake manifold absolute pressure and temperature sensor from the engine harness.

Set the multimeter to measure resistance.

Measure the resistance from the pressure signal pin in the engine harness ECM connector to engine block ground. Repeat the short-to-ground check from the temperature signal pin in the engine harness ECM connector to engine block ground.

Both short-to-ground checks
must show a multimeter reading of 100k ohms or more (open circuit). If the circuit is
not open, repair or replace the engine harness. Refer to Procedure
019-204, or
019-043.

Disconnect both engine harness ECM connectors from the ECM.

Disconnect the intake manifold absolute pressure and temperature sensor from the engine harness.

Set the multimeter to measure resistance.

Measure the resistance from the pressure signal pin in engine harness ECM connector 1 to all other pins in connector 1. Repeat the pin-to-pin check from the temperature signal pin to all other pins in the connector, and from the pressure/temperature return pin to all other pins in the connector.

All pin-to-pin checks
must show a multimeter reading of 100k ohms or more (open circuit). If the circuit is
not open, there is a short circuit between the pins being tested. Repair or replace the engine harness. Refer to Procedure
019-204, or
019-043.

Measure the resistance from the pressure signal pin in engine harness ECM connector 1 to all pins in engine harness ECM connector 2. Repeat the pin-to-pin check from the temperature signal pin in ECM connector 1 to all pins in ECM connector 2, and from the pressure/temperature return pin in ECM connector 1 to all pins in ECM connector 2.

All pin-to-pin checks
must show a multimeter reading of 100k ohms or more (open circuit). If the circuit is
not open, there is a short circuit between the pins being tested. Repair or replace the engine harness. Refer to Procedure
019-204, or
019-043.