Roadmaster Estate Wagon V8-305 5.0L (1991)
Wiring Diagram For Crank Signal
CIRCUIT DESCRIPTION:
Crank signal is a 12.0 volt signal to the ECM during cranking to allow enrichment and cancel diagnostics until engine is running. The crank signal is also
an input to the Diagnostic Energy Reserve Module (DERM) for the Supplemental Inflatable Restraint (SIR) system. When the DERM senses the engine
is being cranked, it will perform a bulb check on the "INFL REST" light.
TEST DESCRIPTION: The numbers below refer to circled numbers on the diagnostic chart.
1.
Checks for normal (cranking) voltage to terminal "C9" of the ECM. Test light should be "ON" during cranking.
2.
Checks to determine if the source of the blown fuse was a faulty ECM. Also, check crank signal to DERM for a short to ground. See WARNING
statement below.
WARNING: This vehicle is equipped with a Supplemental Inflatable Restraint (SIR). For cautions when performing service on or around SIR
components or wiring, see SERVICE PRECAUTIONS Failure to follow Service Precautions may result in an air bag deployment, personal injury, or
unneeded SIR system repair.
