GM Service Manual Online
For 1990-2009 cars only

Circuit Description

Caution: Refer to SIR Caution in the Preface section.

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

The cruise control switch is an input to the body control module (BCM). The BCM monitors the cruise control set/coast and resume/accelerate 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 set/coast and resume/accelerate switch signal circuit when a switch is applied.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B3794 Cruise Control Function Request Circuit

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 set/coast and resume/accelerate 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 .

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step determines if a condition is present.

Step

Action

Values

Yes

No

Schematic Reference: Cruise Control Schematics

Connector End View Reference: Master Electrical Component List

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With the scan tool, observe the Cruise Control Switch parameter in the body control module (BCM) data list.

Does the Cruise Control Switch parameter display Error?

--

Go to Step 3

Go to Step 4

3

  1. Turn OFF the ignition.
  2. Remove the inflatable steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
  3. Disconnect the cruise control switch.
  4. Turn ON the ignition, with the engine OFF.
  5. With the scan tool, observe the Cruise Control Switch parameter in the BCM data list.

Does the Cruise Control Switch parameter display Error?

--

Go to Step 9

Go to Step 11

4

  1. Turn the cruise On/Off control switch ON.
  2. With the scan tool, observe the Cruise Control Switch parameter in the body control module (BCM) data list.

Does the Cruise Control Switch parameter display Error?

--

Go to Step 7

Go to Step 5

5

  1. Activate the cruise control set/coast switch.
  2. With the scan tool, observe the Cruise Control Switch parameter in the body control module (BCM) data list.

Does the Cruise Control Switch parameter display Error?

--

Go to Step 7

Go to Step 6

6

  1. Activate the cruise control resume/accelerate switch.
  2. With the scan tool, observe the Cruise Control Switch parameter in the body control module (BCM) data list.

Does the Cruise Control Switch parameter display Error?

--

Go to Step 7

Go to Diagnostic Aids

7

Important: The cruise control On/Off switch must be turned ON in order to correctly view the set/coast switch and the resume/accelerate switch resistance values with the DMM.

  1. Turn OFF the ignition.
  2. Remove the inflatable steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
  3. Disconnect the cruise control switch.
  4. With a DMM, measure the resistance of the cruise control switch between the ignition 1 voltage circuit and the cruise control set/coast and resume/accelerate switch signal circuit.
  5. Individually activate and hold the cruise control function switches while measuring the resistance value of each cruise control function switch.

Do the cruise control function switch resistance values measure between the specified values?

Off = O.L.

On = 7.8 K-8.6 K

Resume = 2.7 K-3.0 K

Set = 1.2 K-1.3 K

Go to Step 8

Go to Step 11

8

Test the ignition 1 voltage circuit for a high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 15

Go to Step 10

9

Test the cruise control set/coast and resume/accelerate switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

10

Test the cruise control set/coast and resume/accelerate switch signal circuit for a high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

11

Inspect for poor connections at the harness connector of the cruise control switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 15

Go to Step 13

12

Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

13

Replace the cruise control switch. Refer to Steering Wheel Control Switch Assembly Replacement .

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 15

--

15

  1. Install the inflatable steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
  2. Enable the inflatable restraint steering wheel module. Refer to SIR Disabling and Enabling .
  3. Use the scan tool in order to clear the DTCs.
  4. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

--

Go to Step 2

System OK