Workshop Manuals Factory service & repair Vauxhall
Vauxhall Astra J05 · Body Systems
05 · Body & interior

DTC B3950 or B3951

Make
Vauxhall
Model
Astra J
Section
Lighting › Other Information › DTC B3950 or B3951
Body SystemsDTC B3950 or B3951

DTC B3950 or B3951

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 Descriptors

DTC B3950 02: Left Rear Turn Signal Circuit Short to Ground
DTC B3950 04: Left Rear Turn Signal Circuit Open
DTC B3951 02: Right Rear Turn Signal Circuit Short to Ground
DTC B3951 04: Right Rear Turn Signal Circuit Open

Diagnostic Fault Information



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

Left Rear Turn Signal
B3950 02
B3950 04
1
-

Right Rear Turn Signal
B3951 02
B3951 04
2
-

1. Left rear turn signal lamp always ON

2. Right rear turn signal lamp always ON
 

Circuit/System Description

Ground is applied at all times to the turn signal/multifunction switch. When the turn signal/multifunction switch is placed in either the turn right or turn left position, ground is applied to the body control module (BCM) through either the right turn or left turn signal switch signal circuit. The BCM then applies a voltage to the front/side and rear turn signal lamps through their respective voltage supply circuits.

Conditions for Running the DTC

The appropriate turn signal is active.

Conditions for Setting the DTC

B3950 02 or B3951 02

The BCM detects a short to ground on the control circuit.

B3950 04 or B3951 04

The BCM detects an open control circuit.

Action Taken When the DTC Sets

The appropriate turn signal lamp is inoperative.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

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


Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, perform the appropriate Rear Turn Signal/Hazard Lamp test. The appropriate rear turn signal/hazard lamp should be ON/OFF.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate rear turn signal lamp.
2. Test for less than 5 Ω between the appropriate rear turn signal lamp ground circuit harness connector listed below and ground:
  •  E42L Tail Lamp Assembly - Left harness connector terminal B
  •  E42R Tail Lamp Assembly - Right harness connector terminal C
⇒ If greater than the specified value, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the appropriate rear turn signal lamp control circuit harness connector listed below and ground.
  •  E42L Tail Lamp Assembly - Left harness connector terminal C
  •  E42R Tail Lamp Assembly - Right harness connector terminal B
4. Command the appropriate rear turn signal lamp test ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
⇒ If the test lamp is always ON, test the signal 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 signal 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 the circuits test normal, replace the appropriate rear turn signal lamp.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•  Control Module References for BCM replacement, setup and programming

Parts & tools for this job For Vauxhall Astra

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