No spark

Asked by Jan 30, 2017 at 11:08 PM about the 1998 GMC Sierra C/K 2500

Question type: Maintenance & Repair

Ive got a 1998 GMC C2500 5.7L Vortec. Ive done a motor
swap from a 1998 Chevrolet 1500 Z71 4x4 5.7L Vortec.
I got the motor running in my truck back in October and it
was misfiring due to having the firing order wrong. After i
got the spark plug wires right on the distributor everything
was running good until i hooked up my exhaust. After i got
my exhaust hooked up the motor started to stall out and
then died. I tried cranking it and nothing. I started to
diagnose that it was lack of spark, so i checked the crank
sensor thinking thats what was causing the problem and
replaced it,  nothing. I check out and replaced the cap and
rotor, along with the magnetic cam sensor, and ignition
coil. Still nothing. Ive got good ground on the motor too. Ive
got 12v going to the coil and from the coil to distributor but
no spark at the spark plugs. Ive even swapped the ecu from
the donor truck and motor to mine and it throws the
security light. Ive got the distributor in time, and replaced
almost everything but the ignition control module by the
ignition coil. Could the ICM be the reason ive got no spark?

2 Answers


Sure does sound like the ICM may not be working correctly ! I would go ahead and change it. If the truck was running a way to check if the ICM is no good, You can wiggle each of the wires and sometimes the truck will stall..


I'm thinking it is with the security system, can you do a reset procedure? And yes, the Ignition Control Module if bad would definitely not make it have spark. You can have that tested at an auto parts store.

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