GM Service Manual Online
For 1990-2009 cars only

Circuit Description

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

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description .

DTC Symptom

DTC Symptom Descriptor

08

Signal Invalid

61

Actuator Stuck

Conditions for Running the DTC

    • The cruise switch is ON.
    • The ignition is ON.

Conditions for Setting the DTC

    • The BCM detects an invalid voltage signal on the cruise control + RES switch and - SET switch signal circuit.
    • The above condition is present for 0.5 seconds.

Action Taken When the DTC Sets

    • The BCM stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The Cruise Control System is disabled.

Conditions for Clearing the DTC

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

Diagnostic Aids

For an intermittent, refer to Testing for Intermittent Conditions and Poor Connections.

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 and Accessories 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. Disconnect C1 of the multifunction switch.
  3. Turn ON the ignition, with the engine OFF.
  4. With the scan tool, observe the Cruise Control Switch parameter in the Body and Accessories BCM Data list.

Does the Cruise Control Switch parameter display Error?

--

Go to Step 9

Go to Step 11

4

  1. Turn the cruise control On/Off control switch ON.
  2. With the scan tool, observe the Cruise Control Switch parameter in the Body and Accessories 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 and Accessories 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/accel switch.
  2. With the scan tool, observe the Cruise Control Switch parameter in the Body and Accessories 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 resistance values with the DMM.

  1. Turn OFF the ignition.
  2. 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.
  3. 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/accel 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/accel switch signal circuit for a high resistance. Refer to Circuit Testing and Wiring Repairs.

Did you complete the repair?

--

Go to Step 15

Go to Step 12

11

Inspect for poor connections at C1 of the multifunction 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 Turn Signal Multifunction Switch Replacement.

Did you complete the replacement?

--

Go to Step 15

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14

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

Did you complete the replacement?

--

Go to Step 15

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15

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

--

Go to Step 2

System OK