Discussion:
loss of vref no spark

I recently replaced head gaskets on a customers forklift. Once it was back together and time to fire it up no spark. It's a2005 with the 4.3 vortec on propane. As soon as I plug in the ignition control module I lose my 5 volt reference. If however I take the icm off its mount my vref is no longer grounded. I have so far chased every wire in case of a pinch, replaced cam sensor and icm with known good ones and pulled out a lot of hair! There seems to be power going everywhere it should bearing in mind I don't have a diagram for this rig.

The serial number is L005V08098D. Any input would be supremely awesome! Cheers
  • Posted 15 Dec 2015 11:29
  • By wally_v
  • joined 15 Dec'15 - 4 messages
  • British Columbia, Canada
It's your oil... it needs a new motor.
Showing items 1 - 3 of 3 results.
Today I put a known good crank sensor in and no difference. Very audible electric hum with the key on coming from the ecm. Goes away when the ignition control module is unplugged. Still no spark...still no start. Any more ideas?
  • Posted 18 Dec 2015 08:52
  • By wally_v
  • joined 15 Dec'15 - 4 messages
  • British Columbia, Canada
It's your oil... it needs a new motor.
Thanks for the quick reply ed t. I will try the crank sensor in the morning. Pretty sure the 4.3 is not adjustable in this respect. If I probe the harness and rotate the motor by hand I should see a change in value though if it's working right? I should have added that I had the front of the motor apart to change the internal balance shaft bearings. Timing gears lined up after 5 rotations before it went together. However I obviously had the crank sensor out and off.
  • Posted 16 Dec 2015 00:58
  • By wally_v
  • joined 15 Dec'15 - 4 messages
  • British Columbia, Canada
It's your oil... it needs a new motor.
crank sensor? (?air gap for the crank sensor?)
  • Posted 15 Dec 2015 23:08
  • By edward_t
  • joined 5 Mar'08 - 2,334 messages
  • South Carolina, United States
"it's not rocket surgery"

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