Circuit Description
The SBM controls the theatre dimming. The SBM grounds the lamps directly. The output will turn the lamps off by fading out. If there is a short to voltage in CKT 157, a fault condition is present and a DTC will set.
Conditions for Setting the DTC
The SBM detects a short to voltage in CKT 157 for more than 0.15 seconds.
Action Taken When the DTC Sets
| • | Stores a DTC B2458 in the SBM memory. |
| • | No driver warning message will be displayed for this DTC. |
Conditions for Clearing the DTC
| • | A short to voltage is no longer detected by the SBM on CKT 157 |
| • | A history DTC will clear after 50 consecutive ignition cycles if the condition for the fault is no longer present. |
| • | Using the on-board diagnostic (clearing DTC) feature. |
| • | Using a scan tool. |
Diagnostic Aids
The following conditions may cause an intermittent malfunction to occur:
| • | An intermittent short to voltage in CKT 157 |
| • | A short to voltage internal to the SBM |
If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while wiggling the wiring and the connectors. This can often cause the malfunction to appear.
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
-
Always perform the SBM Diagnostic System Check before attempting to diagnose a DTC B2458.
-
This test inspects for a short to voltage in CKT 157 (GRY).
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Did you perform the Body Control Module (SBM) Diagnostic System Check? | -- | Go to Step 2 | ||
Does the test light illuminate? | -- | Go to Step 3 | Go to Step 4 | |
3 | Repair the short to battery positive voltage (B+) in CKT 157 (GRY). Refer to Wiring Repairs in Wiring Systems. Is the circuit repair complete? | -- | Go to Step 5 | -- |
4 |
Is the SBM replacement complete? | -- | Go to Step 5 | -- |
5 |
Are all of the DTCs cleared? | -- | -- |
