Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Revs not going to idle

Please note that my suggestion above Laurens was to interrupt only the yellow/white speed signal wire which normally runs from speed distribution bombtail to the chassis loom plug to benefit only the ECU. I imagine it could be easily separated out at this bombtail leaving the other wires to distribute the speed signal to speedo and TSM. I see no reason to suspect the yellow/red and yellow/black wires on loom which appear to be common reference lines, given you have reported the car runs fine with sensor plug removed, and their loom wiring still in place. Furthermore a short to ground on either would compromise the several associated sensors. In any case it would be difficult to achieve without cutting the wires!

Ref Chris and Bruce's suggestions, I suppose a short to ground on either of the reference wires on the sensor itself could compromise (although doubt engine would run at all) but I understand you have already tried a completely different speed sensor from your other car to no avail, with intermittent idle remaining.

It would only be a temporary fix but I would be interested to learn the outcome when you are able and willing to try this, and it would hopefully leave your car driveable.