Safari Van M V6-262 4.3L (1985)
FIGURE NO. 2 - ECM - ASSEMBLY
1986 MODEL 4.3L TBI ENGINES
The cold engine idle speed of the 1986 models is to be reduced by the replacement of the PROM, reference Figure No. 2. 1986 model vehicles built
before VINS listed below require PROM replacement
GMC
GB524481
Federal Emissions
GB524599
California Emissions
Chevrolet
GB203188
Federal Emissions
GB203623
California Emissions
Vehicles built after these VIN breakpoints have the recalibrated PROM factory installed.
NOTE:
Any time the PROM is installed backwards and the ignition switch turned on, the PROM is destroyed and must be replaced.
1.
Disconnect negative battery cable.
2.
Remove kick panel from right side of the vehicle (1 screw) interior.
3.
Remove ECM (2 screws).
4.
Disconnect electrical harnesses from ECM module.
5.
Remove ECM cover (2 screws).
6.
Remove PROM from ECM and replace with new PROM, P/N 16068877 (Federal), P/N 16068926 (California).
7.
Replace ECM cover.
8.
Reconnect electrical harness.
9.
Secure ECM module to its mounting location.
10.
Replace kick panel.
PARTS LIST
Label
(1985 Model Only)
P/N 10066488
PROM
Federal/High Altitude
P/N 16068877
Emissions
PROM
California Emissions
P/N 16068926
Technical Service Bulletin # 85T105
Date: 861201
Fuel - Revised Fast Idle Adjustment Speeds
GMC NUMBER:
85-T-105
SECTION:
6C - Engine Fuel
DATE:
December, 1986
SUBJECT:
REVISED FAST IDLE ADJUSTMENT SPEEDS
MODELS:
1985 M VAN WITH 4.3L V6 (VIN CODE N) AND AUTOMATIC TRANSMISSIONS
THIS BULLETIN CANCELS AND SUPERCEDES CHEVROLET DEALER SERVICE BULLETIN 85-209 DATED JULY, 1986, ALL COPIES OF
WHICH SHOULD BE DESTROYED.
Some 1985 M vans equipped with the 4.3L V6 engine and automatic transmissions may experience harshness when shifting from Park or Neutral into
gear. This condition only occurs when the engine is on fast idle (cold engines) and the engine fast idle speed is set at 2200 rpm.