Circuit/System Testing

Ignition OFF, disconnect the harness connector at the throttle body. Allow sufficient time for the ECM to completely power down.
Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal C and ground.
- If greater than 5 ohms, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal E and ground.
- If less than 4.8 volts, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
- If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
Verify the scan tool TP sensor 2 voltage is greater than 4.8 volts.
- If less than 4.8 volts, test the signal circuit terminal F for a short to ground. If the circuit tests normal, replace the ECM.
Install a 3A fused jumper wire between the signal circuit terminal F and the low reference circuit terminal C of the TP sensor 2. Verify the TP sensor 2 voltage is less than 0.1 volt.
- If greater than 0.1 volt, test the TP sensor 2 signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
Ignition OFF, disconnect the harness connector at the ECM.
Test for less than 5 ohms of resistance on the TP sensor 2 circuits between the following terminals:
- ECM C1 5-volt reference circuit terminal 39 to terminal E.
- ECM C1 signal circuit terminal 89 to terminal F.
- If greater than 5 ohms, repair the affected circuit.
Test for infinite resistance between TP sensor 1 signal circuit terminal D and TP sensor 2 signal circuit terminal F.
- If less than infinite resistance, repair the short between TP sensor 1 signal circuit and TP sensor 2 signal circuit.
If all circuits test normal, replace the throttle body.