For 1990-2009 cars

### Circuit Description

The cruise control switch is an input to the instrument panel module (IPM). The IPM monitors the cruise control set/coast, resume/accelerate switch signal circuit in order to detect when the driver has requested to perform a cruise control switch function. The IPM also detects a scheduled voltage signal on the cruise control Set/Coast and Resume/Accel switch signal circuit, indicating the On/Off switch is applied. The ECM receives the function request of the cruise control switch on GMLAN serial data signal circuit.

### DTC Descriptor

The diagnostic procedure supports the following DTCs:

DTC B3794 Cruise Control Function Request Circuit

The vehicle has DTCs including the DTC symptoms. For more information on DTC symptoms, refer to DTC Symptom Description .

DTC Symptom | DTC Symptom Descriptor
--- | ---
01 | Short to B+
08 | Signal Invalid
59 | Overtime Circuit/Component Protection

### Conditions for Running the DTC

• | The cruise control on/off switch is ON.

• | The ignition is ON.

### Conditions for Setting the DTC

When one of the following conditions occurs, the IPM will set DTC B3794.

#### B3794 01

The IPM detects that a high voltage signal on the cruise control set/coast and resume/accel switch signal circuit for more than 5 seconds.

#### B3794 08

The IPM detects that an invalid voltage signal on the cruise control set/coast and resume/accel switch signal circuit.

#### B3794 59

The IPM detects that a voltage signal on the cruise control set/coast and resume/accel switch signal circuit for more than 60 seconds.

### Actions Taken When the DTC Sets

• | The IPM stores the DTC information into memory when the diagnostic procedure 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 conditions for setting the DTC are no longer present.

• | The history DTC clears after 50 ignition cycles without failure.

• | The IPM receives a clear code command from the scan tool.

### Diagnostic Aids

The following are the correct switch resistance value range and readings displayed as the cruise control parameters when the switches are pressed one by one in the Body and Accessory/Cruise Control/IPM/Input Data List. If no switch is pressed, the resistance value should be infinite.

Switch Function | Resistance Value Range (Ω) | Counts
--- | --- | ---
OFF | O.L. | 0
On | 7.8-8.6K Ω | 29
Resume | 2.7-3.0K Ω | 76
Set | 1.2-1.3K Ω | 148

• | Make sure the Set/Coast or Resume/Accel switch has not been stuck in the ON position.

• | If there is intermittent condition, 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 | Have you conducted Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Turn ON the ignition.
2. Install a scan tool.
3. Switch on the Cruise Control.
4. Use the scan tool to observe the Cruise parameters in Body and Accessory IPM Data List.

Is the cruise control display equal to or greater than the specified value?

35 Counts

Go to Step 5

Go to Step 3

3 |

1. Turn OFF the ignition.
2. Disconnect the multifunction switch C2.
3. Ignition ON/Engine OFF.
4. Measure the voltage of the remote radio control head accessory supply voltage circuit.

Is the measured voltage within the specified value?

B+

Go to Step 4

Go to Step 10

4 | Important: The cruise control on/off switch must be turned ON in order to correctly view the set/coast switch resistance value with the DMM.

1. Turn OFF the ignition.
2. With a DMM, measure the resistance of the cruise control switch between the remote radio control head accessory supply voltage circuit and the cruise control set/coast and resume/accel switch signal circuit.
3. When measuring the resistance of each cruise control function switch, turn on and press the cruise control function switch respectively.

Is the measured resistance of the cruise control function switch within the specified value?

Off = O.L.

On = 7.8-8.6K

Resume = 2.7-3.0K

Set = 1.2-1.3K

Go to Step 7

Go to Step 8

5 | Important: The cruise control on/off switch must be turned ON in order to correctly view the set/coast switch resistance value with the DMM.

1. Turn OFF the ignition.
2. Disconnect the multifunction switch C2.
3. With a DMM, measure the resistance of the cruise control switch between the remote radio control head accessory supply voltage circuit and the cruise control set/coast and resume/accel switch signal circuit.
4. When measuring the resistance of each cruise control function switch, turn on and press the cruise control function switch respectively.

Is the measured resistance of the cruise control function switch within the specified value?

Off = O.L.

On = 7.8-8.6K

Resume = 2.7-3.0K

Set = 1.2-1.3K

Go to Step 6

Go to Step 8

6 | Test the cruise control set/coast and resume/accel. switch signal circuit for a short to the voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9
7 | Test the cruise control set/coast and resume/accel. switch signal circuit for high resistance. Refer to Circuit Testing and Wiring Repairs . Is the repair complete? | -- | Go to Step 13 | Go to Step 9
8 | Inspect for poor connections at the multifunction switch C2. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11
9 | Inspect for poor connections at the harness connector of the body control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12
10 | Repair the high resistance in the ignition 1 voltage circuit. Refer to Circuit Testing and Wiring Repairs . Is the repair complete? | -- | Go to Step 13 | --
11 | Replace the cruise control switch. Refer to Turn Signal Multifunction Switch Replacement . Have you finished the replacement? | -- | Go to Step 13 | --
12 | Replace the body control module. Refer to Control Module References for replacement, setup, and programming. Have you finished the replacement? | -- | Go to Step 13 | --
13 |

1. Clear away all DTCs with scan tool.
2. Operate the vehicle according to the conditions for running the DTC.

Does the DTC set again?

--

Go to Step 2

System OK