GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

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

DTC Descriptor

DTC B3596 5a: Hazard Warning Switch Stuck

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Hazard Switch Signal

B3596 5a

B3596 5a

1

--

Hazard Switch Telltale Control

B3795 02

B3795 02

B3795 05

B3795 0f

Hazard Switch Ground

--

1

--

--

1. Hazard Lamps Malfunction

Circuit/System Description

The hazard flashers may be activated in any power mode. The hazard switch is located on the accessory control panel and is permanently grounded through ground G205. When the hazard switch is placed in the ON position, ground is applied through the hazard switch signal circuit to the instrument panel cluster (IPC). The IPC responds by sending a serial data message to the underhood electrical center (UEC) and the rear electrical center (REC) requesting the front and rear turn signal lamps be illuminated in an ON and OFF duty cycle. The UEC and REC respond by applying voltage to there respective turn signal control circuits illuminating the front and rear turn signal lamps ON and OFF. The IPC is also responsible for cycling both turn signal indicators ON and OFF. The IPC illuminates the hazard switch telltale by applying voltage to the hazard switch telltale signal circuit.

Conditions for Running the DTC

    • Battery voltage must be between 9-16 volts.
    • Hazard lamps ON.

Conditions for Setting the DTC

The DTC will set when the IPC detects a short to ground or an open/high resistance in the hazard switch signal circuit.

Actions Taken When the DTC Sets

When DTC B3596 05 is present, the hazard switch signal circuit will be disabled.

Conditions for Clearing the DTC

    • The condition responsible for setting the DTC no longer exists.
    • A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the hazard switch.
  2. Ignition OFF, verify a test lamp illuminates between B+ and the ground circuit terminal 2.
  3. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify the scan tool Hazard Warning Switch parameter is OFF.
  5. If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the IPC.
  6. Install a 3A fused jumper wire between the signal circuit terminal 6 and ground. Verify the scan tool Hazard Warning Switch parameter is ON.
  7. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the IPC.
  8. If all circuits test normal, replace the hazard switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front Seat Heater Switch Replacement
    •  Control Module References for IPC replacement, setup, and programming