Circuit Description
The cruise control switch is an input to the instrument panel module (IPM). The IPM monitors the cruise control set/coast and resume/accel switch signal circuit in order to detect when the driver has requested a cruise control switch function. The IPM detects a predetermined voltage signal on the cruise control set/coast and resume/accel switch signal circuit indicating which cruise control switch function is being requested by the driver. The engine control module (ECM) receives the requested cruise control switch function via the GMLAN serial data signal circuit.
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 |
|---|---|
01 | Short to B+ |
08 | Signal Invalid |
59 | Circuit/Component Protection Time Out |
Conditions for Running the DTC
| • | The cruise control on/off switch is ON. |
| • | The ignition is ON. |
Conditions for Setting the DTC
The IPM will set DTC B3794 when one of the following conditions are present:
B3794 01
The IPM detects a high voltage signal on the cruise control set/coast and resume/accel switch signal circuit for greater than 5 seconds.
B3794 08
The IPM detects an invalid voltage signal on the cruise control set/coast and resume/accel switch signal circuit.
B3794 59
The IPM detects a voltage signal on the cruise control set/coast and resume/accel switch signal circuit for greater than 60 seconds.
Action Taken When the DTC Sets
| • | The IPM 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 50 malfunction-free ignition cycles. |
| • | The IPM receives a clear code command from the scan tool. |
Diagnostic Aids
The following are the correct switch resistance value ranges and the correct counts that are displayed in the Cruise parameter in the Body and Accessories/Cruise Control/IPM/Inputs data list, when each switch is pressed individually. If no switch is pressed the resistance value should be infinite.
Switch Function | Resistance Value Range (ohms) | Counts |
|---|---|---|
OFF | O.L. | 0 |
On | 7.8-8.6K ohms | 29 |
Resume | 2.7-3.0K ohms | 76 |
Set | 1.2-1.3K ohms | 148 |
| • | Ensure that the set/coast or the resume/accel switch is not stuck or sticking in the engaged position. |
| • | For an 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 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Does the Cruise display at or above the specified value? | 35 Counts | Go to Step 5 | Go to Step 3 |
3 |
Does the voltage measure at 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 values with the DMM.
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 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 values with the DMM.
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 6 | Go to Step 8 |
6 | 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 13 | Go to Step 9 |
7 | 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 13 | Go to Step 9 |
8 | Inspect for poor connections at C2 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 13 | Go to Step 11 |
9 | Inspect for poor connections at the harness connector of the body control module (BCM). 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 . Did you complete the repair? | -- | Go to Step 13 | -- |
11 | Replace the cruise control switch. Refer to Turn Signal Multifunction Switch Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
12 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
