Checking the PCM Power and Ground Circuits

*CHECKING THE PCM POWER AND GROUND CIRCUITS

For a complete wiring diagram Consult Diagrams/Electrical.

Diagnostic Test

1. PCM WIRING OR CONNECTORS
Turn the ignition off.
Using the wiring diagram/schematic as a guide, inspect the wiring and each connector at the PCM.
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Were any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 2

2. CHECKING THE PCM GROUND CIRCUITS




Turn the ignition off.

CAUTION: 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 12 volts, check the PCM ground circuits.
Wiggle test each circuit during the test to check for an intermittent open in the circuit.

NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.

Is the test light illuminated and bright?

Yes

- Go To 3.

No

- Repair the PCM ground circuit(s) for an open circuit or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

3. CHECKING THE PCM FUSED IGNITION CIRCUITS




CAUTION: 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.

Turn the ignition on.
Using a 12 volt test light connected to ground, check the PCM Fused Ignition circuits.
Check each circuit with the ignition on, engine running position, and during cranking.
Wiggle test each circuit during the test to check for an intermittent open in the circuit.

NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.

Is the test light illuminated and bright?

Yes

- Go To 4.

No

- Repair the open or short to ground in the PCM Fused Ignition circuits.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. CHECKING THE PCM FUSED B+ CIRCUITS




Turn the ignition off.

CAUTION: 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, check the PCM Fused B+ circuits.
Wiggle test each circuit during the test to check for an intermittent open in the circuit.

NOTE: The test light should be illuminated and bright with the ignition on and not illuminated with the ignition off. Compare the brightness to that of a direct connection to the battery.

Is the test light illuminated as described above?

Yes

- Test complete.

No

- Repair the open or short to ground in the PCM Fused B+ circuit(s) for as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.