Vehicle - Excessive Hydrocarbon Exhaust Emission

Number: 86-233

Section: 6E

Date: April, 1987

SUBJECT: STATE EMISSION TESTING INSPECTION MAINTENANCE


MODELS: 1985-86 S/T TRUCKS AND M VANS WITH THE 2.5L L4 ENGINE (VIN CODE E) AND

MANUAL TRANSMISSION

Some 1985-86 S/T trucks or M vans with 2.5L engines and manual transmissions may experience difficulty meeting the hydrocarbon (HC) exhaust emission requirements of state inspection maintenance test programs. If this condition cannot be corrected using the service procedures in Section 6E-Engine Emissions of the appropriate service manual, the following service PROMs are available from GMSPO to repair the condition. Use the PROM replacement procedure in Section 6E-Engine Emissions for PROM replacement.

Service Rear
PROM Model Engine Transmission Axle Tire Size

1228389 M Van 2.5L (LN8) 4-Spd Man (MR2) 3.42 (GU6) All

1228390 M Van 2.5L (LN8) 4-Spd Man (MR2) 3.73 (GT4) All

1228391 M Van 2.5L (LN8) 4-Spd Man (MR2) 4.10 (GT5) All

1228392 M Van 2.5L (LN8) 5-Spd Man (ML3) 3.73 (GT4) All

1228393 M Van 2.5L (LN8) 5-Spd Man (ML3) 4.10 (GT5) All

1228381 S Pickup/ 2.5L (LN8) 4-Spd Man (M73) 3.73 (GT4) All
Extended Cab

1228385 S Blazer/ 2.5L (LN8) 4-Spd Man (M73) 3.73 (GT4) All

T (All) 2.5L (LN8) 4-Spd Man (MC9) 3.73 (GT4) All
4-Spd Man (M73) 4.11 (HO4) P235/75R15

1228386 S Blazer/ 2.5L (LN8) 4-Spd Man (MC9) 4.11 (HO4) All

T (All) 2.5L (LN8) 4-Spd Man (MC9) 4.11 (HO4) All
4-Spd Man (M73) 4.11 (HO4) All Tires Except
P235/75R15

1228382 S Longbed 2.5L (LN8) 4-Spd Man (M73) 4.11 (HO4) All
Pickup

1228383 S (All) 2.5L (LN8) 5-Spd Man (ML3) 3.73 (GT4) All

1228384 S Pickup/ 2.5L (LN8) 5-Spd Man (ML3) 4.11 (HO4) All
Extended Cab
1228388 T (All) 2.5L (LN8) 5-Spd Man (ML2) 4.11 (HO4) P235/75R15

1228387 S Blazer/ 2.5L (LN8) 5-Spd Man (ML3) 4.11 (HO4) All

1228353 S (All) 2.5L (LN8) 4-Spd Man (M73) 3.42 (GU6) All

The following codes identify specific transmissions.

NOTICE: Borg Warner transmissions used in S/T trucks can be identified by the separate bell housing to transmission. Isuzu transmissions are a complete assembly.

MC9 - Borg Warner 4 Speed
ML2 - Borg Warner 5 Speed
ML3 - Borg Warner 5 Speed
MR2 - Muncie 4 Speed
M73 - Isuzu 4 Speed

Use applicable labor Time and Operation Numbers.