P0670

DTC P0670

CIRCUIT DESCRIPTION
The glow control system is operated when the engine coolant temperature is low, which allows easier engine starting. If the ignition switch is turned ON when the engine coolant temperature is low, the engine control module (ECM) illuminates the glow indicator lamp and turns ON the glow plugs via the glow plug controller. After a fixed time passes, the ECM turns OFF the glow indicator lamp and the glow plugs via the glow plug controller.

The glow plug controller has the ability to perform internal diagnostics for voltage and the output state of the glow plugs. If the glow plug controller senses an open in the voltage feed circuit to the glow plugs, or a glow plug controller system voltage error, the glow plug controller will send an error message to the ECM via the controller area network (CAN) communication bus.

Condition for Running the DTC
- DTCs U0073 and U0106 are not set.
- The battery voltage is between 10-16 volts.
- The ignition switch is ON.

Condition for Setting the DTC
- The glow plug controller detects system voltage is too low.

OR
- The glow plug controller detects an open in all 4 glow plug circuits.

Action Taken When the DTC Sets
- The ECM illuminates the malfunction indicator lamp (MIL) on the second consecutive driving cycle when the diagnostic runs and fails.
- The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Freeze Frame/Failure Records on the second consecutive driving cycle when the diagnostic runs and fails.

Condition for Clearing the MIL/DTC
- The ECM turns OFF the MIL after 3 consecutive driving cycles when the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic after the ECM turns OFF the MIL.
- Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
- A charging system problem may set this DTC.

If an intermittent condition is suspected, the following may cause an intermittent:
- Faulty glow plugs
- Poor connections
- Misrouted harness
- Rubbed through wire insulation
- Broken wire inside the insulation

Check for the following conditions:
- Poor connection at glow plug controller: Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
- Damaged harness: Inspect the wiring harness for damage. If the harness appears to be OK, observe the "DTC P0670 Last Test" display on the scan tool with engine running while moving connectors and wiring harness. A change in the display will indicate the location of the fault.

DTC P0670
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Engine Control Module (ECM) Connector End Views

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