Checking Control Panel

FAULT-TRACING INFORMATION

Condition
No diagnostic trouble codes (DTCs)
The fault is permanent.

Possible source

Seat with memory
- Open-circuit on wiring between control panel and control module.
- Contact resistance in terminals.
- Loose contacts in terminals.
- Defective control panel.
- Defective control module.

Seat without memory
- Open-circuit on wiring between control panel and motors.
- Contact resistance in terminals.
- Loose contacts in terminals.
- Defective control panel.

Fault symptom(s)
- Seat will not move forward/backward.
- Seat will not adjust for height.
- No backrest angle adjustment.
- Memory activation does not work

CHECKING THE CONTROL BUTTONS STATUS




- Ignition OFF.
- Select scrolling values.

Activate the seat functions in both directions using the control buttons and read off the status for each button.

Activate the tour memory buttons and read off the status. Refer to Parameter Tables. Other Parameter Tables

The status for each function should change from NOT ACTIVE to ACTIVE when the seat is operated.

If reading is OK:
- Fault not found

CHECKING, CONTACT RESISTANCE AND OXIDATION




- Ignition OFF.
- Disconnect 10-pin connector B.
- Check and correct the 16-pin connector B for loose contact and contact resistance and oxidation.

CONNECTING THE BREAK-OUT BOX
- Ignition OFF.
- Connect break-out box to 16-pin connector. Refer to Break-Out Box. Connecting The Break-out Box

CHECKING CONTROL BUTTONS




- Ignition OFF.
- Connect an ohmmeter between the break-out box socket to the appropriate button and ground (socket 36), Connector D. Refer to Break-Out Box. Signal Tables

- The ohmmeter should read 0 ohm when the respective buttons are pressed.

If reading is OK refer to Checking the Control Module.

If reading is incorrect refer to Checking for an Open-Circuit.

CHECKING FOR AN OPEN-CIRCUIT




Check leads between control panel and control module for open-circuit.
If a fault is detected, try a new control panel.
Then refer to Verification listed below.

CHECKING THE CONTROL MODULE




- Ignition OFF.
- Connect up seat in car. Refer to Wiring Up. Wiring Up For Voltage Measurement

Select scrolling values.
Activate the seat functions in both directions using the control buttons and read off the status for each button.
Activate the four memory buttons and read off the status. Refer to Break-Out Box. Other Parameter Tables

The status for each function should change from NOT ACTIVE to ACTIVE when the seat is operated.

If reading is OK refer to Fault-tracing information listed below.

If reading is incorrect continue with Replace Component.

REPLACE COMPONENT




Try a new control module.
hen continue with Verification listed below.

FAULT-TRACING INFORMATION
No faults detected on the control panel. The fault is probably due to contact resistance in the terminals.

Then continue with:
- Fault corrected

VERIFICATION





Hint: After carrying out the repair, check that the fault has been remedied as follows:
- Ignition OFF.
- Reinstall components, connectors etc.
- Connect up seat in car. Refer to Voltage Measurement. Wiring Up For Voltage Measurement
- Select scrolling values.
- Activate the seat functions in both directions using the control buttons and read off the status for each button.
- Activate the four memory buttons and read off the status.
- The status for the defective button should change from NOT ACTIVE to ACTIVE when activated.

If reading is OK:
- Fault corrected

If reading is incorrect continue with Fault-Tracing Information.

FAULT-TRACING INFORMATION
The fault should now have been diagnosed and corrected. Since this is not the case the fault-tracing has failed.
Do you want to exit fault-tracing?

Yes:
- Fault not corrected

No, refer to Checking the Control Buttons Status listed at beginning of article.

CHECK CONTROL BUTTON




- Ignition OFF.
- Remove seat from car.
- Connect up seat in car according to Voltage Measurement. Wiring Up For Voltage Measurement
- Disconnect the connector as required; the 6-pin connector B7 or the 2-pin B8.
- Ignition ON.

Connect a voltmeter between ground and the following positions in the B7/B8 connectors:

- B7:1: Seat height adjustment upwards at the front edge
- B7:2: Seat height adjustment downward at the front edge
- B7:3: Seat height adjustment upwards at the rear edge
- B7:4: Seat height adjustment downward at the rear edge
- B7:5: Seat adjustment forwards
- B7:6: Seat adjustment backwards
- B8:1: Backrest adjustment backward.
- B8:2: Backrest adjustment forwards.

Activate the respective functions using the control buttons. The voltmeter should read battery voltage when a corresponding function is activated.

If reading is OK:
- Fault not found

If reading is incorrect:
Refer to Replace Component.

Replace component




Check that the emergency stop button has not stuck in the down position.
Try a new control panel.

Then continue with:
- Fault corrected