April 5, 2026: LEMON Manuals is launched! Read the announcement.

Self-Diagnostic System: Notes

Body Control Module (BCM) is equipped with a self-diagnostic system, which detects system Diagnostic Trouble Codes (DTCs) or abnormalities. When a malfunction occurs, BCM will store a DTC. See BCM DTC DEFINITIONS table. Malfunctions are recorded as history/intermittent failures or as current failures. Current DTCs indicate BCM has detected a fault which is currently present. A history DTC indicates that BCM has previously detected a malfunction that does not currently exist.

A scan tool can be used to retrieve and clear DTCs. Scan tool also has several features used to help locate an intermittent condition. When scan tool is used for system tests, it will display values actually seen or commanded by various systems (i.e., BCM, PCM). This will usually include the following types of information:

Analog Data Input

Displays analog input seen by system.

Inputs/Outputs

Displays digital values as seen by system, and provides indication of whether input or output has cycled.

Special Functions (Output Controls)

Allows for outputs of system to be set at a desired value (ON or OFF). This will only indicate if BCM is sending appropriate commands, not what action was actually taken.

Clear Codes

Will erase DTCs for system currently selected (if problem still exists in system, DTC may immediately reset).

BCM DTC DEFINITIONS

DTC ⁽¹⁾

Description

B0160 ⁽²⁾

Temp Sensor Circuit Low

B0162 ⁽²⁾

Temp Sensor Circuit Open

B0931 ⁽²⁾

Compass Sensor Circuit Malfunction

ECU Malfunction

B1003 ⁽³⁾

Programming Mode Active Message Not Received

Keep Alive Memory (KAM)

Device Power No. 3 Circuit Open

Device Ground No. 1 Circuit Open

Power Mode Master Input Circuit Mismatch

Retained Accessory Power Circuit Low

Retained Accessory Power Circuit High

Battery Rundown Protection Circuit Low

Battery Rundown Protection Circuit High

High Power Control Circuit Low

High Power Control Circuit High

B2752 ⁽⁴⁾

Horn Relay Coil Circuit Low

B2753 ⁽⁴⁾

Horn Relay Coil Circuit High

B2823 ⁽²⁾

Trip Odometer Reset Switch Circuit Low

B2947 ⁽⁵⁾

Security System Sensor Power Circuit Low

B2948 ⁽⁵⁾

Security System Sensor Power Circuit High

B2957 ⁽⁵⁾

Security System Sensor Data Circuit Low

B2958 ⁽⁵⁾

Security System Sensor Data Circuit High

B2960 ⁽⁵⁾

Security System Sensor Data Incorrect But Valid

B3031 ⁽⁵⁾

Security System Controller In Learn Mode

B3033 ⁽⁵⁾

Security System Indicates Tamper

B3069 ⁽⁶⁾

Fight Front Door Key Unlock Circuit Low

B3102 ⁽³⁾

Keyless Entry Data Link Circuit Low

B3103 ⁽³⁾

Keyless Entry Data Link Circuit Low

B3106 ⁽³⁾

Keyless Entry Data Link Parity Error

B3127 ⁽⁶⁾

Left Front Door Only Unlock Circuit Low

B3128 ⁽⁶⁾

Left Front Door Only Unlock Circuit High

B3132 ⁽⁶⁾

All Door Unlock Circuit Low

B3133 ⁽⁶⁾

All Door Unlock Circuit High

B3137 ⁽⁶⁾

All Door Lock Circuit Low

B3138 ⁽⁶⁾

All Door Lock Circuit High

B3272 ⁽⁶⁾

Right Front/Left Front Door Lock/Unlock Switch Circuit Low

U1000 ⁽⁷⁾

Class 2 Serial Data Link Malfunction

Class 2 Data Link Shorted To Ground

Class 2 Data Link Shorted To Power

Class 2 Data Link Shorted To Ground/Power

⁽¹⁾	For DTCs not listed, repair appropriate system as necessary.

⁽²⁾	See ANALOG INSTRUMENT PANELS - IMPALA & MONTE CARLO article.

⁽³⁾	See REMOTE KEYLESS ENTRY SYSTEMS - IMPALA & MONTE CARLO article.

⁽⁴⁾	See STEERING COLUMN SWITCHES - IMPALA, INTRIGUE & MONTE CARLO article.

⁽⁵⁾	See ANTI-THEFT SYSTEM - IMPALA & MONTE CARLO article.

⁽⁶⁾	See POWER DOOR LOCK - IMPALA & MONTE CARLO article.

⁽⁷⁾	See CLASS 2 COMMUNICATION MALFUNCTION under SYSTEM TESTS.