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Ask AMEDEE Your Own Question
Category: Chevy
Satisfied Customers: 26416
Experience:  ASE certified tech ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
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Chevrolet C2500 4x2: 1999 3/4 ton pickup, 454, cranks fine,

Customer Question

1999 3/4 ton pickup, 454, cranks fine, has no spark during cranking but will attempt to start when releasing key from crank to run? exhibits this probelm after sitting a few days, runs excellent when running.
Submitted: 2 years ago.
Category: Chevy
Expert:  AMEDEE replied 2 years ago.
Hello and welcome! Does the check engine light come on with the key on? Can I start by getting your VIN?
Customer: replied 2 years ago.
I'll have to respond with the VIN later, I left home before you responded. The MIL functions correctly, no codes stored or present. I need to know how/what tells the coil to fire during cranking mode? Fuel is present during cranking, when you release from crank to run the engine will sputter as it's then getting spark, but not spinning fast enough to run. Problem is intermittent, and is more prevelent after the truck sits for more than a dew days.
Expert:  AMEDEE replied 2 years ago.
Ok sounds good! Please respond with the VIN
Customer: replied 2 years ago.
Expert:  AMEDEE replied 2 years ago.
Thank you for the VIN! Let me do some research for you and reply back shortly
Expert:  AMEDEE replied 2 years ago.
Hello and sorry for the delay!
The ignition module and crankshaft position sensor work together to determine when the ignition coil fires spark. Either one could go bad causing a no spark condition.
IF it happens intermittently when cranking or releasing the key, you could have a bad ignition switch as this send power to the coil and ignition module.
Also, be sure that the distributor cap and rotor are in good shape.
Customer: replied 2 years ago.
Does power run thru the ignition switch in cranking mode and go directly to the ignition module, or does the switch somehow signal the ECU which in turn sends power to the ignition module? Trying to isolate either the switch or ECU? Seems strange that the problem occurs after the truck has sat for several days? Thanks
Expert:  AMEDEE replied 2 years ago.
Hello and sorry for the delay! Would you like me to send you a wiring diagram of the ignition module and circuit?
Customer: replied 2 years ago.
Sure-I'll look for
It and respond w any questions. Thanks
Expert:  AMEDEE replied 2 years ago.
Hello and sorry for the delay! Here is a wiring diagram of the power supply to the ignition coil and ignition module. The power wire is the pink wire. It gets powered up with the key in the ON and CRANK position.

Expert:  AMEDEE replied 2 years ago.
It'sCustomerfrom just answer. I am just checking in to see how things are going and to see if you need any further assistance? Please let me know!