Suburban 3/4 Ton 4WD V8-305 5.0L (1986)
13. Fully extend ISC Plunger by applying 12 volts to terminal "D" and grounding lead to terminal "C" of the ISC Motor Connection. Leave power
applied only long enough to extend the plunger.
14. Manual transmission: Using Tool J-29607 or BT-8022 or equivalent, turn ISC Plunger to obtain ISC adjustment RPM (Maximum Authority) shown
in carburetor charts.
15. Automatic Transmission:
a.
With transmission in PARK, using Tool J-29607, BT-8022 or equivalent, preset ISC plunger to obtain 1500 RPM.
b.
With parking brake set and drive wheels blocked, place transmission in drive. Using Tool J-29607 or BT-8022 or equivalent, turn ISC
Plunger to obtain ISC adjustment RPM (Maximum Authority) shown in carburetor charts.
Plunger - Maximum Adjustment
16. Recheck ISC "Maximum Authority" RPM with voltage applied to Motor (Step 13). Motor will ratchet at full extension with power applied.
17. After adjustment of ISC plunger, measure distance from back side of plunger head to ISC nose piece, Dimension "B". Dimension must NOT exceed
that shown by plunger type as either identified by plunger length or letter identification.
18. Fully retract ISC Plunger (Step 8). Place transmission in PARK (AUTO Trans.) or NEUTRAL (MANUAL Transmission) and turn ignition "Off".
Disconnect 12 Volt Power source, Ground lead, Tachometer and Dwell Meter. With ignition "Off" reconnect four Terminal Harness connectors 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.
