Skip to content
Tahoe / Yukon Service Manual

DTC B1A4B

Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptors Accessory AC and DC Power Control Module Relay DTC B1A4B Diagnostic Fault Information

Circuit Number Circuit Description Short to Ground Open/High Resistance Short to Voltage Signal Performanc
4629 B+ — — B1A4B —
4628 Control — — B1A4B —

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 reports voltage when K9 Body Control Module is commanding off. Actions Taken when DTC Sets Indicator flashes 110V outlet disabled 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 Circuit/System Verification

  1. Ignition ON.
  2. Verify DTC B1A4B is setting as current.. ⇒ If DTC is current Refer to: Circuit/System Testiing. ⇓ If DTC is not set as current
  3. A fault is not currently present and may be an intermittent condition. Circuit/System Testing
  1. Ignition OFF. Disconnect the X1 connector at the T1 DC/AC Converter Control Module. Ignition ON.
  2. Verify a test lamp does not illuminate between control circuit terminal 1 and ground. ⇒ If test lamp does illuminate 2.1. Test for a short to voltage on circuit 4629. ⇒ If a short to voltage is found, repair the fault on the circuit. ⇓ If a short to voltage is not found. 2.2. Test for a short to voltage on circuit 4628. ⇒ If a short to voltage is found, repair the fault on the circuit. ⇓ If a short to voltage is not found. 2.3. Replace the X50A Engine Wiring Harness Junction Block. ⇓ If the test lamp does not illuminate
  3. Replace the T1 DC/AC Converter Control Module.
  4. Clear DTCs. Operate the vehicle under Conditions for Running the DTC.
  5. Verify DTC B1A4B does not reset. ⇒ If DTC does reset Replace the K9 Body Control Module. ⇓ If the DTC does not reset
  6. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Accessory AC and DC Power Control Module Replacement 120-Volt Accessory Power Receptacle Replacement Engine Wiring Harness Junction Block Replacement