DTC B1579

Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor DTC B1579 Rear Closure Shut Face Switch LED Control Circuit Symptom Byte Information: Symptom Byte List Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performanc
Control	B1579 11	1	2	—
Low Reference	—	3	—	—
1. B70 Liftgate Close Switch — backlight= Inoperative 2. B70 Liftgate Close Switch — backlight= Always On 3. B70 Liftgate Close Switch = Inoperative

Circuit/System Description For an overview of the component/system, refer to: Interior Lighting Systems Description and Operation

Circuit	Description
Control	High Control
Low Reference	Grounded through the control module.

	Component	Description
	B70 Liftgate Close Switch	Illumination lamps are used as backlight for switches or panel areas.
	K194 Rear Gate Module	The control module K194 controls the liftgate motor function depending on inputs from a variety of

Component	Description
	sensors, switches and serial data information from other control modules.

Conditions for Running the DTC Ignition » On / Vehicle » In Service Mode Conditions for Setting the DTC Control Circuit = Short to Ground — For greater than 60 s Actions Taken When the DTC Sets Backlight Dimming = Inoperative Conditions for Clearing the DTC A current DTC will clear when the diagnostic runs and passes. A history DTC will clear after 40 consecutive malfunction-free ignition cycles. Reference Information Schematic Reference Liftgate Schematics Connector End View Reference Master Electrical Component List Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References Circuit/System Verification

1. Open the liftgate.

Note

The K194 Rear Gate Module will only command the B70 Liftgate Close Switch to illuminate for 10 minutes after liftgate has been opened. Liftgate must be closed and opened to activate B70 Liftgate Close Switch backlight.

2. Verify the B70 Liftgate Close Switch is illuminated ⇒ If not the specified state Refer to: Circuit/System Testing ⇓ If the specified state
3. All OK. Circuit/System Testing
4. Ignition/Vehicle & All vehicle systems » Off
5. Open the liftgate.
6. Disconnect the electrical connector: B70 Liftgate Close Switch
7. Verify a test lamp turns On between the test points: Control circuit terminal 2 & Low Reference circuit terminal 1 ⇒ If the test lamp does not turn On 4.1. Ignition/Vehicle » Off & Remove » Test lamp 4.2. Disconnect the electrical connector: X4 @ K194 Rear Gate Module 4.3. Test for infinite resistance between the test points: Control circuit terminal 2 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇓ If infinite resistance 4.4. Test for less than 2 Ω between the test points: Control circuit terminal 2 @ Component harness & Terminal 8 X4 @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K194 Rear Gate Module ⇓ If the test lamp turns On
8. Ignition/Vehicle » Off
9. Disconnect the electrical connector: X4 @ K194 Rear Gate Module
10. Ignition » On / Vehicle » In Service Mode
11. Verify a test lamp does not turn On between the test points: Control circuit terminal 2 & Low Reference circuit terminal 1 ⇒ If the test lamp turns On 8.1. Ignition/Vehicle » Off & Remove » Test lamp 8.2. Ignition » On / Vehicle » In Service Mode 8.3. Test for less than 1 V between the test points: Control circuit terminal 2 @ B70 Liftgate Close Switch & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇒ If less than 1 V » Replace the component: B70 Liftgate Close Switch ⇓ If the test lamp does not turn On
12. Replace the component: K194 Rear Gate Module Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Liftgate Close Switch Replacement For control module replacement, programming, and setup refer to: Control Module References