No spark when cranking
Asked by Falcoholic Jan 27, 2020 at 11:42 AM about the 2000 Chevrolet C/K 2500 Extended Cab LB HD 4WD
Question type: Maintenance & Repair
When I turn the key to the start position there is no spark.
When I release the key it momentarily Sparks. I check this
with a timing light. The coil has continuous 12 volt power
and the three ECM fuses in the under hood fuse box are all
good checking with a test light
3 Answers
Battery has a full charge and connections all good? Primary voltage to ignition coil, pink wire, fuse protected, Hot with key in crank and run. Should not be hot all the time. The feed to the fuse comes from ignition switch. If I understand your post, correctly, I'd probably check/replace ignition switch. I'd hate to see you throw parts at it and it not fix it? Sometimes you can use jumper wire off the positive side of battery and run primary voltage to ignition coil. Ecm 1 fuse 20 amp, underhood fuse box, I'd probably pull that fuse to stop backfeed, then use fuse on the jumper, just in case. good luck
Falcoholic answered 4 years ago
Update: the primary pink wire to the ignition coil checked good as well as the ignition switch and all of the ECM fuses. I then checked the ICM and ran a steps 1 through 4 test at step 3 it proved that the coil was defective. The coil was replaced in the truck now runs. Thank you for your help.
Falcoholic answered 4 years ago
https://easyautodiagnostics.com/gm/4.3L-5.0L- 5.7L/how-to-test-the-icm-1
