DTC B3890
Diagnostic Instructions
DTC Descriptors
| DTC B3890 02: Trailer Backup Lamps Circuit
Short to Ground |
| DTC B3890 04: Trailer Backup Lamps Circuit
Open |
Diagnostic Fault Information
Circuit
|
Short to Ground
|
Open/High Resistance
|
Short to Voltage
|
Signal Performance
|
Trailer Backup Lamps Control
|
3890 02
|
3890 04
|
-
|
-
|
|
| |
Circuit/System Description
When the transmission is placed in the reverse position, the
engine control module (ECM) sends a serial data message to the body
control module (BCM). The message indicates that the gear selector
is in the reverse position. The BCM sends this message to the
trailer lighting converter. The trailer lighting converter then
applies a voltage to the trailer backup lamps through their supply
circuit.
Conditions for Running the DTC
B3890 02 or B3890 04
The appropriate trailer backup lamp signal is active.
Conditions for Setting the DTC
B3890 02
The trailer lighting converter detects a short to ground on the
control circuit.
B3890 04
The trailer lighting converter detects an open control circuit.
Conditions for Clearing the DTC
The condition for setting the DTC is no longer present.
Action Taken When the DTC Sets
The appropriate trailer backup lamp is inoperative.
Reference Information
Schematic Reference
Trailer Connector/Provision 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 Trailer Backup Lamps test. The trailer
backup lamp should be ON/OFF.
Circuit/System Testing
Trailer Backup Lamp Malfunction RPO VQ9
| 1. |
Ignition OFF, test for less
than 5 Ω between the X88 Trailer Connector terminal 3, 11, 13
and ground. |
| ⇒ |
If greater than the specified value, test the
appropriate ground circuit for an open/high resistance. |
| 2. |
Connect a test lamp between
the X88 Trailer Connector terminal 8 and ground. |
| 3. |
Command the Trailer Backup
Lamps test 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 K68 Trailer Lighting 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 K68 Trailer Lighting Control
Module. |
| 4. |
If all the circuits test
normal, test the backup lamp circuit at the trailer. |
Trailer Backup Lamp Malfunction RPO D8G
| 1. |
Ignition OFF, remove the
appropriate bulb and inspect. |
| ⇒ |
If bulb is faulty, replace bulb. |
| 2. |
Ignition OFF, remove the
harness connector of the appropriate component listed below:
|
| |
• |
E5B Backup Lamp - Right
|
| 3. |
Test for less than 5 Ω
between the ground circuit harness connector wiring color WH and
ground. |
| ⇒ |
If greater than the specified value, test the
appropriate ground circuit for an open/high resistance. |
| 4. |
Connect a test lamp between
the appropriate control circuit terminal listed below and
ground: |
| |
• |
E5A Backup Lamp - Left wiring
color BU |
| |
• |
E5B Backup Lamp - Right wiring
color GY |
| 5. |
Command the Trailer Backup
Lamps test 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 K68 Trailer Lighting 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 K68 Trailer Lighting Control
Module. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
Control Module References for trailer lighting converter
replacement, setup and programming
|
