vauxhall Workshop Repair Guides

Vauxhall Workshop Service and Repair Manuals

ABOUT US
DTC B3948 or B3949 > < Reverse Lamps Malfunction - MT

Astra J

Rear Fog Lamps Malfunction

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.

Diagnostic Fault Information



Circuit
Short to Ground
Open/High Resistance
Short to Voltage
Signal Performance

Headlight Switch 12V Reference
1
1
1
-

Headlight Switch Signal
1
1
2
-

Rear Fog Lamps Control
B2540 02
B2540 04
B2540 04
-

1. Rear Fog Lamps Inoperative

2. Rear Fog Lamps Always ON
 

Circuit/System Description

The rear fog lamp switch signal circuit is grounded momentarily by pressing the rear fog lamp switch. The body control module (BCM) energizes the rear fog lamp supply voltage circuit which illuminates the rear fog lamp. With the rear fog lamp switch activated the BCM sends a message via serial data to the instrument cluster requesting the instrument cluster to illuminate the rear fog indicator.

Reference Information


Schematic Reference

Fog Lights Schematics


Connector End View Reference

Component Connector End Views


Description and Operation

Exterior Lighting Systems Description and Operation


Electrical Information Reference


Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

•  Ignition ON, perform the scan tool Rear Fog Lamps Switch parameter. The reading should change between Active/Inactive when changing between pressed and released rear fog lamp switch button.
⇒ If not change between Active and Inactive, refer to Rear Fog Lamp Switch Malfunction.
•  Ignition ON, perform the instrument cluster All Indicators test ON and OFF test. The rear fog indicator should be ON/OFF.
⇒ If not change between ON and OFF, refer to Rear Fog Indicator Malfunction.
•  Ignition ON, perform the Rear Fog Lamp(s) Relay test. The rear fog lamp should be ON/OFF when changing between the commanded states.
⇒ If not change between ON and OFF, refer to Rear Fog Lamp Malfunction.

Circuit/System Testing

Rear Fog Lamp Switch Malfunction

1. Ignition OFF, disconnect the X1 and X3 harness connector at the K9 Body Control Module.
2. Test for less than 0.3 V between the 12 V reference circuit terminal 4 X3 and ground.
⇒ If greater than the specified value, test the 12 V Reference circuit for an short to voltage.
3. Test for infinite resistance between the 12 V reference circuit terminal 4 X3 and ground.
⇒ Test for infinite resistance between the 12 V reference circuit terminal 4 X3 and ground.
4. Test for less than 0.3 V between the signal circuit terminal 9 X1 and ground.
⇒ If greater than the specified value, test the signal circuit for an short to voltage.
5. Test for infinite resistance between the signal circuit terminal 9 X1 and ground.
⇒ If less than the specified value, test the signal circuit for an short to ground.
6. Press and hold the rear fog lamp switch button.
7. Test for 2.0-2.4 kΩ between the signal circuit terminal 9 X1 and the 12 V reference circuit terminal 4 X3.
⇒ If not within the specified range, test the 12 V reference circuit and the signal circuit for an open/high resistance. If the circuit test normal replace the S30 Headlamp Switch.
8. If all circuit test normal, replace the K9 Body Control Module.

Rear Fog Indicator Malfunction

1. Ignition ON
2. Command the instrument cluster All Indicators test ON and OFF with the scan tool. The rear fog indicator lamp should be ON/OFF when changing between the commanded states.
⇒ If the rear fog indicator stays always on or always off, replace the P16 Instrument Cluster.
⇒ If the rear fog indicator is changing between ON and OFF, replace the K9 Body Control Module.

Rear Fog Lamp Malfunction

1. Ignition OFF, disconnect the appropriate harness connector at the appropriate tail lamp listed below:
  •  E43L Liftgate Tail Lamp Assembly - Left
  •  E43R Liftgate Tail Lamp Assembly - Right
2. Test for less than 5 Ω between the appropriate ground circuit harness connector terminal listed below and ground:
  •  E43L Liftgate Tail Lamp Assembly - Left harness connector terminal 3
  •  E43R Liftgate Tail Lamp Assembly - Right harness connector terminal 2
⇒  If greater than the specified value, test the appropriate ground circuit for an open/high resistance.
3. Connect a test lamp between the appropriate control circuit harness connector terminal listed below and ground:
  •  E43L Liftgate Tail Lamp Assembly - Left harness connector terminal 4
  •  E43R Liftgate Tail Lamp Assembly - Right harness connector terminal 1
4. Ignition ON, perform the Rear Fog Lamps Relay Command test. The rear fog lamp should be ON/OFF when changing between the commanded states.
⇒ If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module.
⇒ If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K9 Body Control Module.
5. If all circuits test normal, test or replace the appropriate tail lamp.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•  Control Module References for BCM or instrument panel cluster replacement, setup and programming

DTC B3948 or B3949 > < Reverse Lamps Malfunction - MT