C 1500 Truck 2WD V6-262 4.3L (1989)
Idle Speed: All Technical Service Bulletins
Engine Controls - Idle Speed Rise When Clutch Depressed
Number:
90-320-6E
Section:
6E
Date:
August 1990
Corp. Bulletin No.: 036512
Subject:
IDLE RISE BETWEEN SHIFTS
Model and Year:
1989-90 C/K TRUCKS WITH MANUAL TRANSMISSION AND 4.3L (VIN CODE Z) ENGINE
TO:
ALL CHEVROLET DEALERS
CONDITION:
Some owners of the above trucks equipped with manual transmissions may comment about a slight rise in engine idle speed when
depressing the clutch to shift gears.
CORRECTION:
To correct this condition a new service calibration PROM should be installed. The new calibration increases the rate at which Idle
Air Control (IAC) counts are removed following a rapid closing of the throttle. Use the following VIN breakpoint and application
charts to select the proper PROM usage.
VIN BREAKPOINTS: 1990 Model Year
L1126446
OSHAWA (Plant Code 1)
LZ152371
FORT WAYNE (Plant Code Z)
LE144515
PONTIAC EAST (Plant Code E)
APPLICATIONS: ALL 1989 AND 1990 BUILT PRIOR TO 1990 VIN BREAKPOINTS
