350 SDL cruise control question - Page 2 - PeachParts Mercedes-Benz Forum

pwogaman · #16 01-23-2015, 08:21 AM

Bad hall sensor in the speedo head?

JamesDean · #17 01-23-2015, 08:40 AM

Quote:

Originally Posted by loneranger

Update on my part time project. Made a harness to check CC inputs. I found the female connector had the wires in the right place but some dear soul had turned one of the connectors sideways so it was not plugging in. CC still did not work. I had a dimmer switch go bad on my 90 so I switched the instrument cluster out with the 91. The CC stopped working with 91 instrument cluster in worked again with 90 instrument cluster in. The CC problem is now been isolated to the 91 instrument cluster. I need your help again. Is this something I can fix, can I send it to one of you to repair or do I need to see if I can find a used part (tach?) or cluster? Thanks again for your help! :

The cruise control signal comes out of an IC chip on the speedometer circuit board. You might have a problem on the board itself. If you would like I would be happy to test the instrument cluster and make repairs as needed. I've done work on many instrument clusters. Drop me an email at JamesDean59@gmail.com.

JamesDean · #18 01-23-2015, 08:41 AM

Quote:

Originally Posted by pwogaman

Bad hall sensor in the speedo head?

On the W126 the sensor is in the transmission. The signal goes up to the instrument cluster into a ITT UAF0115/2115 IC chip and then back out of the cluster to other consumers.

The 123/124/201 have the hall sensor in the speedo head. They are driven by a mechanical cable that comes up into the cluster. Later model 124s got the electronic speedo upgrade though, 420/500 I think.