Potentiometer Signal Too High

C A. Diagnostic trouble code (DTC) information





Condition
Motor 3 controls seat height at the rear edge of the seat. If the voltage from the potentiometer for motor 3 to control module terminal V3 exceeds 4.6 V diagnostic trouble code (DTC) PSL/PSR-122 is set.

Possible source
- Contact resistance in terminals.
- Loose contacts in terminals.
- Defective potentiometer, motor 3.
- Open-circuit in ground lead between control module and potentiometer, motor 3.
- Signal wire between control module and potentiometer for motor 3 short-circuited to battery voltage.
- Supply wire between control module and potentiometer for motor 3 short-circuited to battery voltage.
- Defective control module.

Fault symptom(s)
- Memory activation does not work.
- Fault-tracing begins at CB. Potentiometer signal too high.





CB. Potentiometer signal too high

CB1: Checking status
- Ignition OFF.
Select scrolling values and read off the value from the potentiometer for motor 3.

Adjust the seat's height adjustment at rear edge, up and down between the end positions several times using the control buttons.

The potentiometer value must not exceed 4.6 V at any time.

If reading is OK:
- CB13

If reading is incorrect:
- CB2








CB2: Checking resistance in circuit to potentiometer
- Ignition OFF.
- Remove seat from car.
- Disconnect black 14-pin connector C.
Connect an ohmmeter between positions C:7 and C:14 on black 14-pin connector (potentiometer side).

The ohmmeter should read approx. 2200 ohm.

If reading is OK:
- CB8

If reading is incorrect:
- CB3





CB3: Checking potentiometer resistance
- Ignition OFF.
- Disconnect the black 14-pin connector.
- Remove potentiometer on motor 3.
Connect an ohmmeter between two outer terminals on the potentiometer.

The ohmmeter should read approx. 2200 ohm.

If reading is OK:
- CB5

If reading is incorrect:
- CB4

CB4: Replace component
- Test with new potentiometer. Motors and potentiometers underneath seat, Service and Repair

Then continue with:
- CB11





CB5: Checking potentiometer's ground
- Ignition OFF.
- Disconnect 3-pin connector to potentiometer on motor 3.
- Disconnect the black 14-pin connector C.
Connect an ohmmeter between the black 14-pin connector terminal C:14 and the corresponding terminal on the 3-pin connector (brown wire).

The ohmmeter should read approx. 0 ohm.

If reading is OK:
- CB7

If reading is incorrect:
- CB6





CB6: Checking for an open-circuit
Check the brown ground lead between the control module, terminal C:14, and the potentiometer for open-circuit.

Then continue with:
- CB11





CB7: Checking, contact resistance and oxidation
Check the 3-pin connector to the potentiometer on motor 3 for contact resistance and oxidation and take corrective action.

Then continue with:
- CB11





CB8: Checking the supply and signal leads on the potentiometer
- Ignition OFF.
- Disconnect the black 14-pin connector C.
- Connect an ohmmeter between supply lead, terminal C:7, and the six supply leads to the motors, terminals C:1-C:6, in the black 14-pin connector on the potentiometer side.

Connect an ohmmeter between signal lead, terminal C:10, and the six supply leads to the motors, terminals C:1-C:6, in the black 14-pin connector on the potentiometer side.

The ohmmeter should read infinite resistance for all readings.

If reading is OK:
- CB10

If reading is incorrect:
- CB9





CB9: Checking for a short-circuit
The measurements show that the signal lead or supply lead to the potentiometer is short-circuited to battery voltage.

Check the red signal lead between terminal C:7, and the potentiometer on motor 3 for short-circuit to supply.

Check the yellow/red supply lead between terminal C:10, and the potentiometer on motor 3 for short-circuit to supply.

Then continue with:
- CB11





CB10: Checking control module and connector C
Potentiometer and cables are fault-free

Check and correct the 14-pin black connector C for contact resistance and oxidation.
If diagnostic trouble code (DTC) persists after verification, try a new control module, Service and Repair

Then continue with:
- CB11





CB11: 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.
Select scrolling values and read off the value from the potentiometer for motor 3.

Operate the seat height adjustment at the rear edge, running the seat to the end positions in both directions.

The values indicated for potentiometer 3 must not be more than 4.6 V or less than 0.2 V.

If reading is OK:
- Fault corrected

If reading is incorrect:
- CB12

CB12: Fault-tracing information
The verification result shows that the fault persists.
Do you want to exit fault-tracing?

Yes:
- Fault not corrected

No:
- CB1








CB13: Intermittent fault
Check the black 14-pin connector C and potentiometer connector to motor 3 for loose contacts and contact resistance and oxidation.

Check the ground lead between control module, terminal C:14 (brown lead), and the potentiometer on motor 3 for intermittent open-circuit.

Control the signal and supply leads between the control module and the potentiometer on motor 3, terminal C:10 and C:7, for intermittent short-circuit to supply.

Then continue with:
- CB14

CB14: Fault-tracing information
For intermittent faults fault-tracing is not followed by a verification because the fault is not present at this moment.
Do you want to repeat fault-tracing?

Yes:
- CB1

No:
- Operation done.