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Tahoe / Yukon Service Manual

DTC B1A78

Diagnostic Instructions Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach. Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC Descriptors DC/AC Inverter Module Output Circuit Voltage Out of Range DTC B1A78 Circuit/System Description The accessory DC/AC power inverter module receives fuse protected battery voltage and is connected to the 12 V electrical system ground. The accessory power receptacle – 110 V AC has an internal switch, that detects when an AC powered device is plugged into the outlet. When the ignition is ON, and an AC powered device is plugged into the accessory power receptacle – 110 V AC, the normally open switch in the accessory power receptacle – 110 V AC, closes. When the accessory DC/AC power inverter module detects the voltage from the accessory power receptacle – 110 V AC switch, the inverter module begins to supply 110 V AC to the accessory power receptacle – 110 V AC after a 1.5 s delay. The accessory AC power system is protected against circuit overload and circuit shorts to ground. Conditions for Running the DTC Ignition ON Conditions for Setting the DTC The T1 Accessory AC and DC Power Control Module is overloaded twice in an ignition cycle. Actions Taken when DTC Sets Indicator flashes 110V outlet disabled Conditions for Clearing the DTC DTC can only be cleared using scan tool. Diagnostic Aids This DTC is usually caused by a device attempting to pull too much power, not a fault in a component. Reference Information Schematic Reference Cigar Lighter/Power Outlet Schematics Connector End View Reference Master Electrical Component List Description and Operation Power Outlets Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References Circuit/System Verification

  1. Ignition ON.
  2. Clear DTCs.
  3. Verify DTC B1A78 does not reset. ⇒ If DTC resets 3.1. Replace the T1 Accessory AC and DC Power Control Module. 3.2. Verify DTC B1A78 does not reset. ⇒ If DTC resets. Replace the K9 Body Control Module ⇓ If DTC does not reset 3.3. All OK. ⇓ If DTC does not reset
  4. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Accessory AC and DC Power Control Module Replacement Control Module References