Circuit/System Testing
- Ignition OFF, remove the fuse that supplies B+ to terminal X2-56 of the ECM.
- Disconnect the harness connector at the accelerator pedal assembly.
- Test for less than 5 ohms between the appropriate low reference circuit of the APP sensor and ground.
- If greater than 5 ohms, test the low reference circuit of the APP sensor for a short to voltage, or an open/high resistance. If the circuit/connections test normal, replace the ECM.
- Install the fuse that supplies B+ to terminal X2-56 of the ECM.NOTE: The 5-volt reference circuit voltage can be within the specified range with a high resistance in the circuit. If this condition is suspected, refer to DIAGNOSTIC AIDS .
- Ignition ON, test for 4.8-5.2 volts between the appropriate 5-volt reference circuit of the APP sensor and ground.
- If less than the specified value, 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 the specified value, test the 5-volt reference circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
- Observe the appropriate scan tool APP sensor voltage parameter. Verify the voltage is less than 0.3 volt.
- If greater than the specified value, test the signal circuit of the applicable APP sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.
- Install a 3A fused jumper wire between the appropriate signal circuit and the 5-volt reference circuit of the APP sensor. Verify the scan tool APP sensor voltage parameter is greater than 4.8 volts.
- If less than the specified value, test the appropriate signal circuit for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.
- If both APP sensor voltage parameters display greater than 4.8 volts test the signal circuits of the APP sensors for a shorted together condition. If the circuit/connections test normal, replace the ECM.
- If all circuits/connections test normal, test or replace the accelerator pedal assembly.