Question about air bypass valve test


New Member
Mar 15, 2006
Hay guys, could use some help on testing an air bypass valve.

I just purchased a modified 1990 notch that has an idle problem that I've been trying to trace down (rough, unstable, won't idle cold).

Question is: When you unplug connector from the throttle air bypass valve and turn the ignition to the run position (not started) I understand you should be able to read 10v - 12v at the connector. Well I'm only getting .5v - .6v, am I doing something wrong? If not any idea what the problem could be (maybe bad computer or ground?).
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One side of the connector (power, red wire) will read 12 volts. The other side (computer, white/lt blue) will be a square wave that varies in duty cycle.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring

Diagram courtesy of Tmoss & Stang&2birds



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