Potentiometer Signal Too Low

G 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 falls below 0.2 V diagnostic trouble code (DTC) PSL/PSR-223 is set.

Possible source
- Contact resistance in terminals.
- Loose contacts in terminals.
- Defective potentiometer, motor 3.
- Open-circuit in supply lead between control module and potentiometer, motor 3.
- Open-circuit in signal lead between control module and potentiometer, motor 3.
- Signal lead between control module and potentiometer to motor 3 short-circuited to ground.
- Defective control module.

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





G B. Potentiometer signal too low

GB1: 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 between the end positions several times using the control buttons.

The potentiometer value must not fall below 0.2 V at any time.

If reading is OK:
- GD14

If reading is incorrect:
- GB2








GB2: 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:
- GB8

if reading is incorrect:
- GB3





GB3: 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:
- GB5

If reading is Incorrect:
- GB4

GB4: Replace component
Test with new potentiometer. Motors and potentiometers underneath seat, Service and Repair

Then continue with:
- GB12





GB5: Checking supply leads to potentiometer
- 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:7 and the corresponding terminal on the 3-pin connector (red lead).

The ohmmeter should read approx. 0 ohm.

If reading is OK:
- GB7

If reading is incorrect:
- GB6





GB6: Checking for an open-circuit
Check the red supply lead between the control module, terminal C:7, and the potentiometer for open-circuit.

Then continue with:
- GB12





GB7: Checking, contact resistance and oxidation
Check the 3-pin connector to the potentiometer on motor 3 for contact resistance and oxidation.

Then continue with:
- GB12





GB8: Checking potentiometer's signal lead
- Ignition OFF.
- Disconnect the black 14-pin connector C.
Connect an ohmmeter between positions C:7 and C:10 on black 14-pin connector (potentiometer side).

The ohmmeter should read between 100 - 2200 ohm depending on seat position.

If reading is OK:
- GB11

If value is lower:
- GB9

If value is higher:
- GB10





GB9: Checking for a short-circuit
Check the yellow/red supply lead between terminal C:10, and the potentiometer on motor 3 for short-circuit to ground.

Then continue with:
- GB12





GB10: Checking for an open-circuit
Check the yellow/red supply lead between terminal C:10, and the potentiometer on motor 3 for open-circuit to supply.

Then continue with:
- GB12





GB11: 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:
- GB12





GB12: 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:
- GB13

GB13: Fault-tracing information
The verification result shows that the fault persists.
Do you want to exit fault-tracing?

Yes:
- Fault not corrected

No:
- GB1








GB14: Intermittent fault
Check the black 14-pin connector C on the control module and connector on the potentiometer on motor 3 for loose contacts and contact resistance and oxidation.

Check the red supply lead between the control module position C:7, and the potentiometer on motor 3 for intermittent open-circuit.

Check the yellow/red signal lead between the control module position C:10, and the potentiometer on motor 1 for intermittent short-circuit to ground.

If the the fault persists after all checks are completed the fault might be due to linearity fault in the potentiometer. Replace potentiometer on motor 3 with a new one.

Then continue with:
- GB15

GB15: 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:
- GB1

No:
- Operation done