PCM Power and Ground Circuit Test

PCM Power and Ground Circuit Test






For a complete wiring diagram, refer to.

Test Step 1 - PCM Wiring and 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 PCM Verification Test. Refer to => [ PCM Verification Test ] PCM Verification Test.

No

• Go to Test Step 2

Test Step 2 - PCM Ground Circuit Test






• Turn the ignition off.


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 test lamp 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.

• The test lamp should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.

Is the test lamp brightly illuminated?

Yes

• Go to Test Step 3

No

• Repair the PCM ground circuit for an open circuit or high resistance.

• Perform the PCM Verification Test. Refer to => [ PCM Verification Test ] PCM Verification Test.

Test Step 3 - PCM Power Supply Circuit Test







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 lamp connected to ground, check the PCM power supply circuits.

• Wiggle test each circuit during the test to check for an intermittent open in the circuit.

• The test lamp should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.

Is the test lamp brightly illuminated?

Yes

• Go to Test Step 4

No

• Repair the PCM power supply circuit for an open circuit or high resistance.

• Perform the PCM Verification Test. Refer to => [ PCM Verification Test ] PCM Verification Test.

Test Step 4 - PCM Fused Ignition Switch Circuit Test






• Turn the ignition on.


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 lamp connected to ground, check the PCM fused ignition switch circuits.

• Check each circuit with the ignition off, ignition on, engine not running position, and during cranking.

• Wiggle test each circuit during the test to check for an intermittent open in the circuit.

• The test lamp 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.

Does the test lamp illuminate as described above?

Yes

• Test complete.

No

• Repair the PCM fused ignition switch circuit as necessary.

• Perform the PCM Verification Test. Refer to => [ PCM Verification Test ] PCM Verification Test.