The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - ecm test question

hjs · 11-24-2020, 05:28 PM

there's a 'set timing' connector on the wiring harness for tbi years (i think) 87 to 95. it's a tan/black wire.
if you unplug the connector you bypass the ecm, but the motor will run, and you can set initial timing.
would this also be a good way to test for a faulty ecm? it the motor runs with the tan/black wire unplugged, but does not run with it plugged, wouldn't this point to a bad ecm?

11-24-2020, 05:28 PM	#1
hjs Registered User Join Date: Feb 2018 Location: Arnoldsville GA Posts: 15	ecm test question - tbi there's a 'set timing' connector on the wiring harness for tbi years (i think) 87 to 95. it's a tan/black wire. if you unplug the connector you bypass the ecm, but the motor will run, and you can set initial timing. would this also be a good way to test for a faulty ecm? it the motor runs with the tan/black wire unplugged, but does not run with it plugged, wouldn't this point to a bad ecm?