Suburban 3/4 Ton 4WD V8-305 5.0L (1986)
18. Fully retract ISC plunger (step 8). Place transmission in "PARK" (automatic) or "NEUTRAL" (manual) and turn ignition "OFF". Disconnect 12
volt power source, ground lead, tachometer and dwell meters. With ignition "OFF" reconnect four terminal harness connector to ISC motor.
19. "TRICKING" the ISC motor as described will cause the "CHECK ENGINE" light to come on and an ISC motor trouble code to be set. By
restoring the system to normal operation, the light will go out, but the trouble code will continue to be stored as an "INTERMITTENT" problem.
In this case, it will be necessary to clear the diagnostic trouble codes by removing the ECM fuse from the fuse block for about 10 seconds.
Federal
PRELIMINARY PROCEDURES
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Warm engine to normal operating temperature (upper radiator hose hot).
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Turn "OFF" all accessories, including A/C.
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Check Timing (adjust if not to specification). See: Ignition Timing
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Connect tachometer.
CAUTION: Exercise care not to ground the TACH terminal (which is located next to the BAT connector) as this may damage the Electronic
Control Module (ECM) or coil.
CURB IDLE SPEED
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Disconnect and plug vacuum hose to EGR valve and canister purge.
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Adjust curb idle speed.
