DTC B2540
Diagnostic Instructions
DTC Descriptors
| DTC B2540 01: Rear Fog Lamps Control Circuit
Short to Battery |
| DTC B2540 02: Rear Fog Lamps Control Circuit
Short to Ground |
| DTC B2540 04: Rear Fog Lamps Control Circuit
Open |
Diagnostic Fault Information
Circuit
|
Short to Ground
|
Open/High Resistance
|
Short to Voltage
|
Signal Performance
|
Rear Fog Lamp Control
|
B2540 02**
|
B2540 04**
|
B2540 01*
|
-
|
* Fog lamp always ON
** Fog lamp always OFF
|
|
| |
Circuit/System Description
The body control module (BCM) energizes the rear fog lamp by
applying voltage to the rear fog lamp control circuit. When the
rear fog lamp control circuit is energized, the rear fog lamp is
illuminated.
Conditions for Running the DTC
Rear fog lamp activated
Conditions for Setting the DTC
B2540 01
The BCM detects a short to battery on the control circuit.
B2540 02
The BCM detects a short to ground on the control circuit.
B2540 04
The BCM detects an open control circuit.
Action Taken When the DTC Sets
The appropriate fog lamp is inoperative.
Conditions for Clearing the DTC
The condition for setting the DTC is no longer present.
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 Rear Fog Lamp(s) Relay test. The rear
fog lamp should be ON/OFF when changing between the commanded
states.
Circuit/System Testing
| 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.
|
