GM Service Manual Online
For 1990-2009 cars only

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 B3623 00: Steering Wheel Controls Adaptive Cruise Control (ACC) Gap Up/Down Signal Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+

1

B3623 00

--

B3623 00

Adaptive Cruise Control Switch Signal

1

B3623 00

1

B3623 00

1. Cruise Control Malfunction

Circuit/System Description

The body control module (BCM) monitors the adaptive cruise control (ACC) gap adjustment switch signal circuit to determine the driver selected headway. The gap switch is a momentary contact switch that connects a series of resistors. Each switch state, inactive, up and down, corresponds to a specific resistance value. The BCM determines the switch selection by the voltage drop across the resistor. The BCM sets DTC B3623 when it detects a stuck gap up/down switch.

Conditions for Running the DTC

Ignition is in RUN.

Conditions for Setting the DTC

Gap adjustment switch signal circuit remains in the same state for 1 minute.

Actions Taken When the DTC Sets

    • The malfunction indicator lamp (MIL) will not illuminate.
    • The adaptive cruise control (ACC) is disabled.
    • The cruise control system is disabled.
    • Service Radar Cruise message is displayed in the driver information center (DIC).

Conditions for Clearing the DTC

    • The condition responsible for setting the DTC no longer exists.
    • A history DTC will clear after 40 malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Cruise Control Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cruise Control 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 ON, verify that the ACC Gap Switch parameter toggles accordingly between Up, Down and Inactive as the appropriate gap switch is pressed.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the steering wheel controls switch - left.
  2. Ignition ON, test for B+ between the B+ circuit terminal 1 and ground.
  3. If less than the specified value, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. Test for B+ between the B+ circuit terminal 1 and the signal circuit terminal 2.
  5. If less than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. Ignition OFF, disconnect the X2 harness connector at the BCM.
  7. Test for infinite resistance between the signal circuit terminal 57 and ground.
  8. If less than the specified value, test the signal circuit for a short to ground.
  9. If all circuits test normal, test or replace the steering wheel controls switch - left.

Component Testing

  1. Disconnect the harness connector at the steering wheel controls switch - left.
  2. Cruise control switch ON, measure the resistance between terminal 1 and terminal 2 while individually activating and holding each ACC gap function switch and compare the resistance reading to the values in the table below.
  3. If not within the specified resistance range, replace the steering wheel controls switch - left.

Function Switch

Minimum Resistance Value

Maximum Resistance Value

Neutral

O.L.

O.L.

Cancel

1.9k Ohms

2.1k Ohms

Gap Up

3.5k Ohms

3.7k Ohms

Gap Down

6.6k Ohms

6.8k Ohms

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Steering Wheel Control Switch Assembly Replacement
    •  Control Module References for BCM replacement, setup, and programming