The ECI circuit requires the use of vehicle circuit diagrams.
See truck Chassis Electrical Circuit Diagram Manual for circuit numbers, connector and fuse locations.
ECI Circuit Test – With the transmission out of gear and the clutch depressed with wheels safely blocked,
insert a harness between socket Pin 86 and 87 of the starter relay. If the engine cranks when the start switch
is engaged, check for failed ECI relay or problems with the ECM or ECM wiring harness.