make sure the colors match this firs.t
blue-yell jumps to black, black is just ground.
only this wire color is correct for diagnostic mode , to see flash codes, DTCs/
freeze is timing advance spark freeze jumper input.
ISC is for setting ISC duty cycle to 50% (tricky this)
but the DIAG pin is super simple and always works if CEL lamp not burned out. or ECU bad.
![[Image: fed-car-diag.jpg]](https://fixkick.com/CEL/DLC/fed-car-diag.jpg)
blue-yell jumps to black, black is just ground.
only this wire color is correct for diagnostic mode , to see flash codes, DTCs/
freeze is timing advance spark freeze jumper input.
ISC is for setting ISC duty cycle to 50% (tricky this)
but the DIAG pin is super simple and always works if CEL lamp not burned out. or ECU bad.
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