B0978 GMC Possible Causes
- Faulty Ignition Mode Switch
- Ignition Mode Switch harness is open or shorted
- Ignition Mode Switch circuit poor electrical connection
- Faulty Body Control Module (BCM)
First diagnose B0978 GMC code
Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded terminals.
Cost of diagnosing the B0978 GMC code
Labor: 1.0The cost of diagnosing the B0978 GMC code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.
B0978 GMC Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
B0978 GMC MeaningThe Ignition Mode Switch has 3 LEDs that indicate the vehicle power mode. When the vehicle is in the Off mode, the Off LED may illuminate. Pressing the lower button of the ignition mode switch, the vehicle enters the accessory mode and ACC LED will illuminate. Keeping the lower button pressed for about 5-6 seconds, the vehicle enters run mode with the engine off and the START LED will illuminate. All these LEDs have the voltage supplied from the Body Control Module (BCM) through the ignition mode switch supply voltage circuit. The ground path for each LED is controlled by the BCM.
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