timing

V8 • 2WD • AUTOMATIC
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RDR70
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  • 1 POST
1990 chevrolet truck 350 engine will not start with the timing connector pluged in. If the truck is started fist and the connector is then pluged in the timing erractily goes up and down. The dist. has been replaced as well as the proccesor.
Nov 24, 2010 at 11:48 AM
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JDL
  • ✓Experienced Mechanic
  • 16,098 POSTS
Any applicable mil codes? Cranking rpms, it is the ignition module that controls spark timing not the computer. To set timing, my info says to disconnect one wire, tan with black tracer. Is timing ok?

When rpms get above a certain point, the computer puts a ref voltage on that tan wire mentioned, usually around 5 volts. That voltage tells the ignition module to use the signal on the white wire for spark timing. If no signal on white wire your going to have problems. Maybe a wiring circuit issue?
Nov 24, 2010 at 12:25 PM
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