Astro Van M L4-151 2.5L (1985)
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 PROM factory installed.
Notice:
Anytime 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.
1985 - 1986 2.5L TBI Engine
C.
Vehicles equipped with this engine do not require PROM replacements.
D.
Brake Burnish Procedure
On a dry clean level roadway, make twelve stops using the following procedure:
First Stop:
Stop vehicle from 40 mph by applying the brakes to achieve a deceleration rate of 10 ft/sec/sec. (A 10 ft/sec/sec deceleration is
equivalent to stopping the vehicle from 40 mph in 6 seconds.)
Second through Eleventh Stops:
Stop vehicle from 50 mph by applying the brakes to achieve a deceleration rate of 15 ft/sec/sec. (A 15
ft/sec/sec deceleration is equivalent to stopping the vehicle from 50 mph in 5 seconds.)
Twelfth Stop:
Stop vehicle from 40 mph by applying the brakes to achieve a deceleration rate of 10 ft/sec/sec.
In order to allow brake temperatures to stabilize, it will be necessary to drive 1/2 mile between stops without applying brakes. Following
completion of burnish procedure (twelfth stop), drive vehicle 3 miles keeping brake usage to a minimum in order to achieve sufficient brake cool down.
1987 MODELS
Effective 1987 start of production, all Safari/Astro models were manufactured with new wheel cylinders described earlier in this bulletin, however the
new combination valve was not installed in the first several months of production. The new combination valve was installed effective with the following
Vehicle Identification Numbers:
GMC:
HB509335
Chevrolet:
HB137507
1987 vehicles produced prior to these VIN breakpoints can be modified by following the service procedure listed below: