[E28] How to fix your cruise control & OBC speed/mileage functions

[Click]

If both your cruise control and MPG/speed functions on your OBC don't work or are flaky likely the connector on the back of your cluster is making poor contact like mine was. Both the OBC and cruise control module get their speed input from a small blue connector that attaches to the circuit board of the speedometer through a hole in the back of the cluster housing.

The connector.





Can barely see the contacts in there.



There's the top one



Pop the rear cover off



Pop a terminal out paying attention that they are held in with small clips. I used a small flathead screwdriver





The bare terminal



I cleaned the contact surfaces with some crocus cloth, likely an unneeded step



Gently bend the two "legs" towards each other and reinstall





Before and after for the other side





Also cleaned the circuit board contacts a bit, again probably unneeded, they were pretty shiny as is



Reinstall the cluster and you should be set. The blue connector definitely took a good push to get on compared to what it used to be. Go for a drive and enjoy cruise and seeing your gas mileage!

[Nesset]

I really need to do this, thank you for the writeup!

[tschultz]

Should be obvious, but this procedure won't fix your problem if the cause is something like a bad clutch or brake switch, or cruise module...