Code 43, No Crank Signal From Starter

ECM receives a B+ signal when starter is cranking. This signal is used by ECM to activate fuel pump. If signal is not present and engine speed is greater than 800 RPM, Code 43 will set.

1. B+ should be present on the Black/White wire while engine is cranking.
2. When ignition switch is released (engine running), no voltage should be present on Black wire.

Fig 1: Code 43 Flow Chart, No Crank Signal From Starter

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code 43 Schematic, No Crank Signal From Starter

Courtesy of GENERAL MOTORS CORP.