Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2004MALIBU V6-3.5L VIN 8REPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSRELAYS AND MODULES - COMPUTERS AND CONTROL SYSTEMSENGINE CONTROL MODULETESTING AND INSPECTION
2004 Chevrolet Malibu V6-3.5L VIN 8
Engine Control Module: Testing and Inspection
2004 Chevrolet Malibu V6-3.5L VIN 8SECTION Testing and Inspection
POWERTRAIN RELAY DIAGNOSIS
CIRCUIT DESCRIPTION
The powertrain relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the armature contact at all times. The powertrain control module (PCM) supplies the ground path to the relay coil control circuit, via an internal integrated circuit, called an output driver module. When the PCM commands the relay ON, the relay coil creates an electromagnetic field. This electromagnetic field overcomes the spring tension and pulls the armature contact into the stationary contact of the relay load circuit. The closing of the relay contacts allows the current to flow from the battery to the following fuses and relays:
- ETC fuse
- Emission fuse
- A/C relay
- Air pump relay, if equipped
When the ignition switch is turned to the OFF position, power is interrupted to the output driver module in the PCM, and the relay electromagnetic field collapses. This action allows the spring tension pulling on the armature to separate from the relay load circuit contact, which interrupts current flow to the fuses and relays.
If the powertrain relay fails to close, the engine will crank, but will not run. The class 2 communications will be available with the use of a scan tool.
The powertrain relay system diagnosis table assumes that the vehicle battery is fully charged.
TEST
CIRCUIT DESCRIPTION
The powertrain relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the armature contact at all times. The powertrain control module (PCM) supplies the ground path to the relay coil control circuit, via an internal integrated circuit, called an output driver module. When the PCM commands the relay ON, the relay coil creates an electromagnetic field. This electromagnetic field overcomes the spring tension and pulls the armature contact into the stationary contact of the relay load circuit. The closing of the relay contacts allows the current to flow from the battery to the following fuses and relays:
- ETC fuse
- Emission fuse
- A/C relay
- Air pump relay, if equipped
When the ignition switch is turned to the OFF position, power is interrupted to the output driver module in the PCM, and the relay electromagnetic field collapses. This action allows the spring tension pulling on the armature to separate from the relay load circuit contact, which interrupts current flow to the fuses and relays.
If the powertrain relay fails to close, the engine will crank, but will not run. The class 2 communications will be available with the use of a scan tool.
The powertrain relay system diagnosis table assumes that the vehicle battery is fully charged.
TEST
Steps 1 - 3:
Steps 4 - 6:
Steps 7 - 9:
Steps 10 - 12:
Steps 13 - 15:
Steps 16 - 18:
Steps 19 - 23:
Steps 24 - 28:
Steps 29 - 32:
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.