Rex-I Trouble Shooting

[93Regina]

Pin 20 at 4/42 (REX ECU) is suppose to be a ground, but when the C50 connector was opened, I'm reading 1.6 volts at A (ECU Pin 20's wire goes to power stage in above right position), most likely this voltage comes from pin 20 at ECU. Location of 31/33 is at intake manifold for ground

Pin 16 at 4/42 (REX ECU) is the trigger signal for power stage at terminal B

I'll have to further trouble shoot in several days, but it would appear something is amiss. Pin 20 may not be a true ground at ECU, but they may have used a common ground (via intake) for ECU and power-stage's trigger-circuit.

Here's an overall schematic

After opening up both connectors at driver's side of firewall, I checked voltages/grounds at these connectors, and power-stage's wires and discovered this by chance.