GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    â€¢ Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    â€¢ Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    â€¢  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B3794 08: Cruise Control Function Request Circuit Signal Invalid

DTC B3794 61: Cruise Control Function Request Circuit Actuator Stuck

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Steering Wheel Control Supply Voltage

1

B3794

1

B3794

Cruise Control Switch Signal

B3794

B3794

1

B3794

1. Cruise Control Inoperative/Malfunctioning

Circuit/System Description

The cruise control switch is an input to the body control module (BCM). The BCM monitors the cruise control on/off, set/coast, resume/accelerate and cancel switch signal circuit in order to detect when the driver has requested to perform a cruise control function. The BCM detects a specific voltage signal on the cruise control switch signal circuit when a switch is applied.

Conditions for Running the DTC

    â€¢ The cruise switch is ON.
    â€¢ The ignition is ON.

Conditions for Setting the DTC

    â€¢ The BCM detects an invalid voltage signal on the cruise control switch signal circuit.
    â€¢ The above condition is present for greater than 1 second.

Action Taken When the DTC Sets

    â€¢ The BCM stores the DTC information into memory when the diagnostic runs and fails.
    â€¢ The malfunction indicator lamp (MIL) will not illuminate.
    â€¢ The cruise control system is disabled.

Conditions for Clearing the DTC

    â€¢ The DTC becomes history when the fault is no longer present.
    â€¢ A History DTC clears after 100 malfunction-free ignition cycles.
    â€¢ The BCM receives a clear code command from the scan tool.

Diagnostic Aids

    â€¢ Rotate the steering wheel to both steering stops and activate each cruise control switch separately. With a scan tool, observe the Cruise Control Switch parameter in the BCM Cruise Control data list. This will help eliminate the possibility of a internally open or shorted inflatable restraint steering wheel module coil.
    â€¢ For an intermittent, refer to Testing for Intermittent Conditions and Poor Connections .

Reference Information

Schematic Reference

Cruise Control Schematics

Connector End View Reference

    â€¢  Secondary/Configurable Control Connector End Views
    â€¢  Data Communication Connector End Views

Electrical Information Reference

    â€¢  Circuit Testing
    â€¢  Connector Repairs
    â€¢  Testing for Intermittent Conditions and Poor Connections
    â€¢  Wiring Repairs

Circuit/System Verification

Ignition ON, observe the scan tool Cruise Control Switch parameter in the BCM while pressing the various cruise control switches. The reading should be Error.

⇒If the Cruise Control Switch parameter toggles between On, Off, Resume, and Set accordingly with the depressed switches, go to Testing for Intermittent Conditions and Poor Connections .

Circuit/System Testing

Caution: Refer to SIR Caution in the Preface section.

Disable the inflatable restraint steering wheel module when performing this diagnostic. Refer to SIR Disabling and Enabling .

  1. Ignition OFF, remove the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
  2. Disconnect the harness connector at the multifunction switch.
  3. Ignition ON, measure for 10 volts or greater at the 12-volt reference circuit.
  4. ⇒If less than the specified value, check for an open/high resistance or a short to ground on the 12-volt reference circuit.
  5. Test the cruise control switch signal circuit for an open/high resistance, a short to ground or a short to voltage.
  6. If the circuits test normal, test the component. If the component tests normal, replace the BCM.

Component Testing

Caution: Refer to SIR Caution in the Preface section.

Disable the inflatable restraint steering wheel module when performing this diagnostic. Refer to SIR Disabling and Enabling .

  1. Ignition OFF, remove the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
  2. Ignition OFF, disconnect the harness connector C4 at the multifunction switch.
  3. Measure the resistance between terminals 1 and 5 at the cruise control switch side of the connector. Individually activate and hold each cruise control function switch and compare the resistance reading to the values for the On, Off, - SET, and + RES switches.
  4. ⇒If any of the resistance measurements for the On, Off, - SET, and + RES switches are not within the listed resistance values, replace the multifunction switch.

Function Switch

Minimum Resistance Value

Maximum Resistance Value

Off

O.L.

O.L.

On

6.5k Ohms

7.1k Ohms

- SET

1.4k Ohms

1.6k Ohms

+ RES

3.7k Ohms

3.9k Ohms

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    â€¢  Turn Signal Multifunction Switch Replacement
    â€¢  Control Module References for BCM replacement, setup, and programming