Circuit Description
The LH Door Control Module (LDCM) provides an illuminated output control for the LH door switch assembly. This allows the LDCM to illuminate the LH door switch back lighting, memory indicators, and mirror select indicators. The LDCM provides a single power supply for all illuminated light functions. The LDCM uses a Pulse-Width Modulation (PWM) ground output to control the dimming level to the LH door switch back lighting lamp. When the LDCM receives a message on the serial data line indicating that the park lamps or headlamps are ON, the LDCM will control the LH switch illumination by PWM-ing the ground. The LDCM also provides a ground output for the memory 1, memory 2, LH and RH mirror select switch indicators. The LDCM provides a ground output to each of these indicators allowing the LDCM to illuminate the applicable indicator based upon the select switch input information. The LDCM monitors the amount of current draw on all of the illumination lamp control circuits. If the current draw is not within the acceptable range, a malfunction is present and a DTC will set.
Conditions for Setting the DTC
| • | The LDCM detects a high current (short to ground) condition in any one of the following LH door switch control circuits: |
| - | RH or LH mirror indicator |
| - | Memory 1 indicator |
| - | Memory 2 indicator |
| - | LH door switch Illumination lamp |
| • | Condition must be present for 20 ms. |
Action Taken When the DTC Sets
| • | Stores a history DTC B2278 in the LDCM memory. |
| • | The LDCM will disable the malfunctioning indicator. |
| • | This DTC can only be set as a history code even if the malfunction is current. |
| • | No driver warning message will be displayed for this DTC. |
Conditions for Clearing the DTC
| • | The LDCM no longer detects a high current (short to ground) condition in the applicable indicator/lamp control circuit for longer than 20 ms. |
| • | Use the IPC clearing DTCs feature. |
| • | Use a scan tool. |
Diagnostic Aids
| • | The following conditions may cause an intermittent malfunction: |
| - | There is an intermittent short (to voltage or ground) in CKT 157, CKT 580, CKT 1461, or CKT 1504. |
| - | The LH door switch indicator/lamp is shorted. |
| • | Using a scan tool, select LDCM Data and monitor the door switch pad illumination while rotating the interior light dimming switch. The switch illumination level varies based upon the dimming level information the LDCM receives on the serial data link. This checks if the LDCM is able to receive the correct dimming information from the serial data line. |
| • | If the DTC does not reset after the code is cleared, then the problem may be intermittent. Perform the tests shown while moving related wiring and connectors. This can often cause the malfunction to occur. Refer to Intermittents and Poor Connections . |
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
This test checks if all of the LH door switch indicators and lamps illuminate. If the LDCM detects a malfunction in an indicator or lamp circuit, the LDCM will disable the indicator or lamp that the malfunction was detected.
-
This test checks if the LH switch indicator and lamp circuit for an open or short (to ground or voltage).
Step | Action | Value(s) | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Were you sent here from the Power Door Diagnostic System Check? | -- | ||||||||||||
Do all of the indicators/lamps illuminate? | -- | |||||||||||||
Was a problem found and repaired? | -- | |||||||||||||
4 | Replace the LH door switch assembly. Refer to Power Mirror Switch Replacement . Is the replacement complete? | -- | -- | |||||||||||
5 |
Is the replacement complete? | -- | -- | |||||||||||
6 | Check the LH door switch circuit for an intermittent malfunction. Refer to Diagnostic Aids. Was a problem found and repaired? | -- | ||||||||||||
7 |
Does DTC B2278 set as history? | -- | System OK | |||||||||||
8 |
Is the repair complete? | -- | -- |
