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DTC B1448

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 Descriptor

DTC B1448 01: Accessory Power Relay Circuit Short to Battery

DTC B1448 02: Accessory Power Relay Circuit Short to Ground

DTC B1448 04: Accessory Power Relay Circuit Open

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Accessory Power Relay Switch B+

--

1

--

--

Accessory Power Relay Coil B+

1

1

--

--

Accessory Power Relay Coil Control

B1448 02

B1448 04

B1448 01

-

Accessory Power Relay Output Control

1

1

--

--

1. Accessory Power Malfunction

Circuit/System Description

The body control module (BCM) activates the accessory power relay when the ignition switch is in the ACCESSORY or RUN position. The BCM applies ground to the accessory power relay coil control circuit.

Conditions for Running the DTC
    • The system voltage is between 9–16 V.
    • Ignition switch is in the ACCESSORY or RUN position.

Conditions for Setting the DTC

The DTC will set only when the BCM requests the output and there is a short to voltage, short to ground, or open in the ignition voltage circuit.

Action Taken When the DTC Sets

The BCM output driver will be shut down and not supply voltage to the accessory voltage circuit.

Conditions for Clearing the DTC
    • The current DTC will clear when the module request for the output is removed or the malfunction is no longer present.
    • A history DTC clears when the module ignition cycle counter reaches the reset threshold of 40, without a repeat of the malfunction.

Reference Information

Schematic Reference

    •  Power Distribution Schematics
    •  Power Moding Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Mode 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 for scan tool information

Circuit/System Verification

Ignition switch in the ACCESSORY position, the front and rear accessory power receptacles or cigar lighter should work properly.

Circuit/System Testing
  1. Ignition OFF, remove the KR70 Auxiliary Power Relay.
  2. Ignition on, verify that a test lamp illuminates between the B+ circuit terminal 87 and ground.
    3. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the X50A Fuse Block - Underhood.
  3. Ignition ON, verify that a test lamp illuminates between the control circuit terminal 85 and ground.
    4. ⇒If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.
  4. Ignition OFF, verify that a test lamp does not illuminate between B+ and the control circuit terminal 85.
    5. ⇒If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the K9 Body Control Module.
  5. Ignition switch in the ACCESSORY position, verify that a test lamp illuminates between ground and the control circuit terminal 85.
    6. ⇒If the test lamp does not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.
  6. If all circuits test normal, test or replace the KR70 Auxiliary Power Relay.

Component Testing

Relay Test

  1. Ignition OFF, remove the KR70 Auxiliary Power Relay.
  2. Test for 50-100 Ω between the ground circuit terminal 86 and the control circuit terminal 85.
    3. ⇒If not the specified range, replace the KR70 Auxiliary Power Relay.
  3. Test for infinite resistance between the circuit terminals listed below:
    4. • 30 and 85
    • 30 and 86
    • 30 and 87
    • 85 and 87
         ⇒If not the specified value, replace the KR70 Auxiliary Power Relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Fuse Block Replacement
    • Control Module References for control module replacement, setup, and programming
   


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