For a complete wiring diagram Refer to Section 8W.Possible Causes(A209) PCM FUSED B+ CIRCUITPCM NO RESPONSE(F1) PCM FUSED IGNITION SWITCH OUTPUT CIRCUIT(Z903) PCM GROUND CIRCUITSCRANKSHAFT POSITION SENSOR(F855) 5-VOLT SENSOR OPEN/SHORTED(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUNDPCM1. (A209) PCM FUSED B+ CIRCUIT

The scan tool and cable must be operating properly for the results of this test to be valid.Make sure the ignition switch was on while trying to communicate with the PCM.Turn the ignition off.Disconnect the C1 PCM harness connector.Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.Using a 12-volt test light connected to ground probe the appropriate terminal of special tool #8815.Does the test light illuminate brightly?YesGo To 2 NoRepair the open or short to ground in the (A209) Fused B+ circuit. Inspect and replace fuses as necessary.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) 2. (F1) PCM FUSED IGNITION SWITCH CIRCUIT

Using a 12-volt test light connected to ground, probe the (F1) PCM Fused Ignition Switch Output circuit in the appropriate terminals of special tool #8815.Does the test light illuminate brightly?YesGo To 3NoRepair the (F1) Ignition Switch Output circuit. Inspect and replace fuses as necessary.Perform the POWERTRAIN VERIFICATION TEST.(Refer to 9 - ENGINE - STANDARD PROCEDURE) 3. (Z903) PCM GROUND CIRCUITS

Using a 12-volt test light connected to battery voltage, probe the (Z903) PCM ground circuits in the appropriate terminals of special tool #8815.Does the test light illuminate brightly?YesGo To 4NoRepair the (Z903) PCM ground circuits.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) 4. (F855) 5-VOLT SUPPLY CIRCUIT

Turn the ignition off.Connect the C2 PCM harness connector.Disconnect the Crankshaft Position Sensor harness connector.Ignition on, engine not running.Measure the voltage on the (F855) 5-volt Supply circuit.Is the voltage between 4.5 and 5.2 volts?YesGo To 5NoGo To 65. CKP SENSOR

Turn the ignition off.Disconnect the Throttle Body harness connector.Ignition on, engine not running.Measure the voltage on the (F855) 5-volt Supply circuit in the Throttle Body harness connector.Is the voltage between 4.5 and 5.2 volts?YesIf communication is available with a PCM on a like vehicle, replace and program the Powertrain Control Module per Service Information.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) NoReplace the Crankshaft Position Sensor.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) 6. (F855) 5-VOLT SENSOR OPEN/SHORTED

Turn the ignition off.Disconnect the Throttle Body harness connector.Ignition on, engine not running.Measure the voltage on the (F855) 5-volt Supply circuit.Disconnect all the sensors that use the (F855) 5-volt Supply circuit.Did the voltage return to 4.5 to 5.2 volts when disconnecting any of the sensors.YesReplace the sensor that is pulling down the (F855) 5-volt supply.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) NoGo To 77. (F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUNDTurn the ignition off.Disconnect PCM harness connectors.Disconnect all the sensors that share the (F855) 5-volt Supply circuit.Measure the resistance between ground and the (F855) 5-volt Supply circuit at one of the sensor harness connectors.Is the resistance below 100 ohms?YesRepair the short to ground in the (F855) 5-volt Supply circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) NoGo To 88. (F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUNDDisconnect all the sensors that share the (F856) 5-volt Supply circuit.Measure the resistance between ground and the (F856) 5-volt Supply circuit at one of the sensor harness connectors.Is the resistance below 100 ohms?YesRepair the short to ground in the (F856) 5-volt Supply circuit.Perform the POWERTRAIN VERIFICATION TEST.(Refer to 9 - ENGINE - STANDARD PROCEDURE) NoGo To 99. PCMBefore continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.Were there any problems found?YesRepair as necessary.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) NoReplace and program the Powertrain Control Module per Service Information.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)