Control Module/Component Power & Grounds

Poor power or ground connections can cause widely varying symptoms.

1. Check all Powertrain Control Module (PCM) power circuits. Many vehicles have multiple circuits supplying power to the PCM. Other components in the system may have separate power circuits that may also need to be tested. Inspect connections at the module/component connectors, fuses, and any intermediate connections between the power source and the module/component. A test light or a DMM may indicate that voltage is present, but neither tests a circuit ability to carry sufficient current. Ensure that the circuit can carry the current necessary to operate the component.
2. Check all control module ground and system ground circuits. The PCM may have multiple ground circuits. Other components in the system may have separate grounds that may also need to be tested. Inspect grounds for clean and tight connections at the grounding point. Inspect the connections at the component and in splice packs, where applicable. Ensure that the circuit can carry the current necessary to operate the component.