Circuit Description
The BCM interfaces with the DRL control module through circuit 1970 to determine the ambient light operation mode. The BCM communicates this information to the instrument cluster through the Class II serial data link.
Conditions for Setting the DTC
The BCM detects a short to ground or an open in circuit 1970 when turning the ignition switch from start to on.
Action Taken When the DTC Sets
The BCM stores DTC B2602 in memory.
Conditions for Clearing the DTC
| • | When the ignition switch is turned from off to on, a current DTC B2602 is always cleared. If a short to ground or open is still present when the ignition switch is turned from start to on, DTC B2602 will reset as a current DTC. |
| • | A history DTC will clear after 100 consecutive ignition cycles if the condition for the fault is no longer present. |
| • | Using a scan tool. |
Diagnostic Aids
| • | The following conditions may cause an intermittent malfunction to occur: |
| - | An intermittent short to ground in circuit 1970. |
| - | An intermittent open in circuit 1970. |
| - | The DRL module is shorted to ground or open internally. |
| • | If the DTC is a history DTC, the problem may be intermittent. Try performing the tests shown while wiggling wiring and connectors, this can often cause the malfunction to reappear. |
| • | DTC P1626 will set in the Powertrain Control Module (PCM) when the ignition switch is on with the Body Control module (BCM) disconnected. When BCM diagnostics and repairs are completed, refer to Powertrain On Board Diagnostic (OBD) System Check |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step checks for voltage in circuit 1970.
-
This step checks for a short to ground in circuit 1970.
-
This step determines whether circuit 1970 has a short to ground or the DRL control module is faulty.
-
This step checks for a open in circuit 1970.
-
This step checks for a short to ground in circuit 1340.
-
This step checks for an open in circuit 1340.
-
This step determines whether the malfunction is intermittent or the BCM is faulty.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the BCM Diagnostic System Check performed? | -- | ||
Is the test light on? | -- | |||
Using a DMM, measure the resistance between the BCM harness connector C1 terminal C9 and ground. Is the resistance within the specified range? | ∞ | |||
Is the resistance within the specified range? | ∞ | |||
Using a test light, backprobe between the Automatic Headlamp Control Module connector C2 terminal B and ground. Is the test light on? | -- | |||
Using a test light, connect between B+ and Automatic Headlamp Control Module harness connector C2 terminal A. Is the test light on? | -- | Go to Step 11 | ||
Using a test light, connect between the Automatic Headlamp Control Module module harness connector C2 terminal A and ground. Is the test light on? | -- | |||
Does BCM DTC B2602 reset as a current DTC? | -- | |||
9 | Repair short to ground in circuit 1970 between the BCM connector C1 terminal C9 and the Automatic Headlamp Control Module connector C2 terminal B. Is the repair complete? | -- | -- | |
10 |
Is the repair complete? | -- | -- | |
11 | Repair short to ground in circuit 1340. Is the repair complete? | -- | -- | |
12 | Replace the DRL module. Refer to Body Control Module Replacement in Lighting Systems for service procedure. Is the repair complete? | -- | -- | |
13 | Repair poor connection or open in circuit 1340. Is the repair complete? | -- | -- | |
14 | Repair poor connection or open in circuit 1970 between the BCM connector C1 terminal C9 and the Automatic Headlamp Control Module connector C2 terminal B. Is the repair complete? | -- | -- | |
15 | The malfunction is not present at this time. Refer to Diagnostic Aids for additional information regarding this DTC. Is the repair complete? | -- | -- | |
16 |
Are there any BCM current DTCs set? | -- | System OK |
