Good evening,
Another repair in an effort to get my Z4 error free (if ever).
Seat heating stopped working. When pressing the heating button, I see a short flash of the 3 green LEDs, then LED's remain off.
ISTA show error message below.
Detailed view shows this: -17 DegC
Measurements on the middle + right pin of this connector indeed show a broken wire.
Did some measurements by inserting some known resistors.
The sensor in the seat is a NTC, 8 kOhm, approx 4050 Beta.
Using a 10 kOhm NTC (which a very common value), will give you a 5 DegC error!!!!!
An 8 kOhm NTC is much harder to find, but very accurate.
Part number I used: NRCE803K4050B1KS
Make a simple cable
Remove the seat.
Peel the rear small piece of seat cover off.
Insert the sensor assembly 10-15 cm.
Then make a nice wire modification.
Grey wire into the seat is no long needed. Grey wire from connector goes to new sensor.
Brown wire (mass) needs to be split to go to heater and to the new sensor.
Correct ISTA readings:
This repair did cost me 1 hour to do and 1 hour to find the NTC.
Total costs around 20 Euro because of the minimum quantity I had to buy of these NTC's. But the NTC's are like 1 Euro/piece.
Hope this tutorial helps someone
Greetings Matthijs
Another repair in an effort to get my Z4 error free (if ever).
Seat heating stopped working. When pressing the heating button, I see a short flash of the 3 green LEDs, then LED's remain off.
ISTA show error message below.
Detailed view shows this: -17 DegC
Measurements on the middle + right pin of this connector indeed show a broken wire.
Did some measurements by inserting some known resistors.
The sensor in the seat is a NTC, 8 kOhm, approx 4050 Beta.
Using a 10 kOhm NTC (which a very common value), will give you a 5 DegC error!!!!!
An 8 kOhm NTC is much harder to find, but very accurate.
Part number I used: NRCE803K4050B1KS
Make a simple cable
Remove the seat.
Peel the rear small piece of seat cover off.
Insert the sensor assembly 10-15 cm.
Then make a nice wire modification.
Grey wire into the seat is no long needed. Grey wire from connector goes to new sensor.
Brown wire (mass) needs to be split to go to heater and to the new sensor.
Correct ISTA readings:
This repair did cost me 1 hour to do and 1 hour to find the NTC.
Total costs around 20 Euro because of the minimum quantity I had to buy of these NTC's. But the NTC's are like 1 Euro/piece.
Hope this tutorial helps someone
Greetings Matthijs
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