R 3500 P/U 2WD V8-305 5.0L (1987)
PROM - Programmable Read Only Memory: All Technical Service Bulletins
Engine Controls - Improved Driveability/False MIL Lamp
GMC NUMBER:
88-T-25
GROUP:
6E - Engine Emissions
DATE:
July, 1987
CORPORATE
NUMBER:
836501
SUBJECT:
REVISED PROMS - TO IMPROVE DRIVEABILITY AND ELIMINATE FALSE "SERVICE
ENGINE SOON" LIGHTS
MODELS:
1987 R/V, G AND 1988 C/K MODELS WITH 5.0L (VIN CODE H) AND 5.7L (VIN CODE K) ENGINES AND LIGHT DUTY
EMISSIONS
Some 1987-88 R/V, C/K and G models with TBI engines may experience one or more of the following driveability conditions and/or false codes. If
these conditions are experienced, they can be repaired by replacing the PROMS. The new PROMs went into production in mid June, 1987.
DRIVEABILITY CONDITIONS - 5.0L (LO3) TBI ENGINE
1.
Rolling, hunting or surging idles
2.
False Code 54 - Fuel pump circuit (low voltage)
3.
False Code 43 - ESC fault
DRIVEABILITY CONDITIONS - 5.7L (LO5) TBI ENGINE
1.
Rolling, hunting or surging idles.
Notice:
In addition to the PROM change, it will be necessary to reset minimum idle speed, per the procedures on PG 4-22 of the Driveability
and Emissions Book.
A.
Automatic (Drive) 425 plus or minus 25 RPM
B.
Manual (Neutral) 500 plus or minus 25 RPM
2.
Low speed road load surge
3.
Detonation and weak acceleration during warm-up
4.
Poor cold starting at minus 20 degrees Fahrenheit
5.
False Code 24 - Vss circuit fault when using 4 wheel drive low lock.
To repair the above conditions install PROMS per the following charts.
L03 (5.0L) ENGINE
BODY STYLE
SERIES
TRANSMISSION
EMISSION SYSTEM
PROM NO.
Pickup
10/1500
3 Spd. Auto (M40)
Fed. (NA5)
16073446
Pickup
10/1500
3 Spd. Auto (M40)
Alt. (NA6)
16073245
Pickup
10/1500
4 Spd. Auto (MD8)
Fed. (NA5)
16073430
Pickup
10/1500
4 Spd. Auto (MD8)
Alt. (NA6)
16073250
Pickup
10/1500
4 Spd. Auto (MD8)
Calif. (NB2)
16073417
Pickup
10/1500
4 Spd. Man (MY6/M20)
Fed/Alt (NA5/NA6)
16073460
Suburban
10/1500
4 Spd. Auto (MD8)
Fed/Alt (NA5/NA6)
16073395
Suburban
10/1500
4 Spd. Auto (MD8)
Calif. (NB2)
16073399
Pickup
20/2500
4 Spd. Man (M20)
Fed/Alt (NA5/NA6)
16073352
Pickup
20/2500
3 Spd. Auto (M40)
Fed/Alt (NA5/NA6)
16073347
Blazer/Jimmy
10/1500
3 Spd. Auto (M40)
Fed/Alt (NA5/NA6)
16073347
Pickup 4WD
10/1500
3 Spd. Auto (M40)
Fed/Alt (NA5/NA6)
16073347
Pickup
20/2500
4 Spd. Auto (MD8)
Fed/Alt (NA5/NA6)
16073442
Blazer/Jimmy
10/1500
4 Spd. Auto (MD8)
Fed/Alt (NA5/NA6)
16073442
Pickup 4WD
10/1500
4 Spd. Auto (MD8)
Fed/Alt (NA5/NA6)
16073442
Pickup
20/2500
4 Spd. Auto (MD8)
Calif. (NB2)
16073435
Blazer/Jimmy
10/1500
4 Spd. Auto (MD8)
Calif. (NB2)
16073435
Pickup 4WD
10/1500
4 Spd. Auto (MD8)
Calif. (NB2)
16073435
Blazer/Jimmy
10/1500
4 Spd. Man (MY6/M20)
Fed/Alt (NA5/NA6)
16073334
Pickup 4WD
10/1500
4 Spd. Man (MY6/M20)
Fed/Alt (NA5/NA6)
16073334
Chevy Van/
GMC Vandura
10/1500
3-4 Spd. Man (M62/MY6)
Fed/Alt (NA5/NA6)
16073376
Chevy Van/