E30 speedometer blown resistor

[rwtags]

I blew a resistor in my speedometer, It stopped working right after I reflowed all the connectors on the c2 plug tryi g to fix a fuel guage issue.
what would cause the resistors to blow? Taking it back apart I noticed that you could either have the speedometer plug having the missing pin on the bottom of the cluster or the top. I can plug it in either way but I am now not sure which is right.

[Bmjpv]

My speedo had the same problem , 91’ 325ix . Car had been just sitting around , started & moved over (2) years . By itself the speedo would go straight to 110mph when the key turned on . Replaced the VDO board with used parts & all good !

[rwtags]

i will see if i can find a picture, but you can either have one prong above or below, the cluster circuit board is not keyed, and i think that is 100% what blew the circuit board on the speedometer

[rwtags]

So it was caused by me incorrectly connecting the speedometer to the cluster board, here is both possibilities, both were able to be screwed together, none the wiser to me...


and


I believe the blank pin on the bottom is the correct way to install it, if you install it incorrectly you will have no speedometer, and odometer, or trip meter.