Shift Up Indication

Upshift Indication:

When the load on the engine drops below a certain level at the same time as engine speed reaches certain values, the ECM shorts the "SHIFT UP" lamp (47K to ground via pin 55.

The engine speed at which the lamp lights up depends on the intake manifold pressure and the gear that is engaged:
^ 1st: 2000 rpm
^ 2nd: 1900 rpm
^ 3rd: 1800 rpm
^ 4th: 1775 rpm