Circuit Description
The LH Seat Control Module (SCM) has two main power feeds (high and low), and one main ground. The low power feed (battery 1) is used to provide power for the SCM logic and internal driver operation. The high power feed (battery 2) is used to provide power for systems that draw higher amounts of current (motors, lights etc.). For most functions, the SCM will operate properly when vehicle system voltage is between 9.0-16.0 volts. The SCM also monitors the voltage level at battery 1 and battery 2 circuits and can determine if the voltage level received is out of range. If the voltage level is out of range in either circuit , then a malfunction is present and a DTC will set.
Conditions for Setting the DTC
| • | The SCM detects battery 1 voltage range under 8.5 volts or over 16.3 volts. |
| • | Condition must be present for 2 seconds. |
Action Taken When the DTC Sets
| • | Stores a history DTC B0851 in the SCM memory. |
| • | 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 SCM detects battery 1 voltage range between 8.5-16.3 volts for longer than 2 seconds. |
| • | Use the IPC clearing DTCs feature. |
| • | Using a scan tool. |
Diagnostic Aids
| • | 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 Diagnosis in Wiring Systems. |
| • | The following conditions may also cause an intermittent malfunction: |
| - | There is an intermittent open or short to ground in CKT 1740. |
| - | The battery voltage is not within range (8.5-16.3 volts). |
| - | A charging system malfunction. |
| • | Using a scan tool, select SCM Data display and monitor battery 1 voltage while operating the seat adjuster motors. This can determine if battery 1 voltage is affected by these devices and can help duplicate the malfunction. |
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
This test checks if the vehicle's Starting/Charging system is functioning properly. Starting/Charging system malfunctions will cause the SCM to store a history DTC B0851, therefore always repair all Starting/Charging malfunctions first.
-
This test checks the battery 1 voltage using a scan tool. Normal battery 1 voltage range is between 8.5-16.3 volts.
-
This test checks the instrument panel electrical center and CKT 1740 for an open or short to ground. Normal battery 1 voltage range is between 8.5-16.3 volts.
-
This test checks for any other history DTC stored in the SCM memory that may cause a DTC B0851 to set.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Were you sent here from the Power Seat Diagnostic System Check? | -- | Go to Power Seats System Check | |||||||
2 | Verify that the vehicle's Starting/Charging system is functioning properly. Repair any current Starting/Charging malfunctions. Refer to Charging System Check in Engine Electrical. Is the Starting/Charging system functioning properly? | -- | Go to Charging System Check | |||||||
3 | Using a scan tool, select SCM data display and monitor battery 1 data. Does the scan tool display battery 1 voltage within the specified range? | 8.5-16.3 V | ||||||||
4 |
Is the voltage within the specified range? | 8.5-16.3 V | ||||||||
5 | Using a scan tool, select SCM DTC display and check for the following DTCs stored as history:
Are any of these DTCs stored as history? | -- | Go to the Applicable DTC Table | |||||||
6 | Locate and repair an open or short to ground in the instrument panel electrical center or CKT 1740. Is the circuit repair complete? | -- | -- | |||||||
7 | Replace the SCM. Refer to Memory Seat Control Module Replacement . Is the replacement complete? | -- | -- | |||||||
8 | Check the battery 1 circuit for an intermittent malfunction. Refer to Diagnostic Aids. Was a problem found and repaired? | -- | ||||||||
9 |
Does DTC B0851 set as history? | -- | System OK | |||||||
10 |
Is the repair complete? | -- | Go to Power Seats System Check | -- |
