Circuit/System Testing
- Verify that none of the following conditions exist:
- Ignition OFF, disconnect the vacuum hose at the MAP sensor. Connect the J 23738-A
to the vacuum hose.
- Engine idling, verify that 15-20 in Hg of vacuum is available to the MAP sensor.
- If the vacuum is not within the specified range, repair the restriction in the vacuum hose to the MAP sensor.
- Ignition OFF, connect the vacuum hose to the MAP sensor. Disconnect the harness connector at the MAP sensor.
- Ignition ON, test for less than 0.2 volt between the low reference circuit 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 and ground.
- If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit and ground.
- If less than 4.8 volts, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM.
- If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
- Verify that the MAP sensor parameter is less than 12 kPa.
- If greater than 12 kPa, test the signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
- Install a 3A fused jumper wire between the signal circuit and the 5-volt reference circuit. Verify that the MAP sensor parameter is greater than 102 kPa.
- If less than 102 kPa, test the signal circuit 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.