My iCarSoft i980 arrived :-)

When I read stored codes from the overhead control module I'm getting B1888 Sensor N701b1 value implausible.

I think this is the internal temperature sensor?

When I read the actual values I'm seeing what looks like 0.25 C...

I'm guessing I meed to replace the sensor? Am I on the right track and anyone have any experience with this?

Thanks
Gary

 

It's a humidity sensor. Here's a thread where someone replaced it on a CLK with a $2 themistor:

http://www.benzworld.org/forums/c209...re-sensor.html

 

Thank you Rodney, great information as always.

Gary

 

Following up on my previous post. Rodney put me on the right track.

There's a temperature sensor in the overhead console. Part of the unit is a temperature sensitive resistor known as a thermistor. It looks like one of those spiders with very long thin legs (except the spider has 6 legs, the thermistor has only two). Those long thin legs are prone to breaking and the thermistor can go bad. I think a replacement unit is about $350, but a replacement thermistor can be had for 25 cents.

I got a pack of 10 off EBay from Tayda Electronics, the spec on them is:

10 x 10K OHM NTC Thermistor 5mm
B Constant 4050K
Resistance 10K OHM
Temperature -30°C to +125°C
Thermistor Type NTC Thermistor
Tolerance ±5%

My indie sucessfully opened up the overhead console, removed the board, soldered in a new thermistor and put it all back together.

The climate control now works as you would expect. In the past on hot days the AC would over cool the cabin. On short journeys and mild days you wouldn't notice, but after around an hour driving on a hot day the cabin would start to get really cold. Turning up the heat a few degrees at a time made no difference. Turning to max heat warmed things up, but the minute you dialed it down the AC would over cool again.

I'm guessing the climate control is quite sophisticated and uses a combination of sensors to manage the heating and cooling. In my case loss of the overhead sensor resulted in over cooling. I've read of cases - maybe in very cold climates - where it resulted in over heating the cabin.

More info and pictures here, the SL isn't identical, but the thermistor is the same and the unit is near enough that my indie was able to figure it out - http://www.benzworld.org/forums/c209...re-sensor.html

Thanks to Rodney for the pointer and also for suggesting the iCarSoft i980. Even if you don't plan on working on these cars yourself it's worth having around.

Gary

 

Glad you got it fixed! Don't credit me with that - i just "borrowed" the fix from a guy on benzworld.

 

Great result, thanks for sharing.

Maybe someone is harvesting spider legs to make these thermistors!?