EXPERTEC TSB (91-157-6E)

Publication date: 1991-09-30
Reference number: 91-157-6E

EXPERTEC TSB

TECHNICAL SERVICE BULLETIN

Reference Number(s): 91-157-6E, Date of Issue: 09/30/91

SERVICE ENGINE SOON LIGHT (CODE 22)

Model(s): 1991 Chevrolet Caprice, Camaro

1991 Chevrolet Trucks

1991 Chevrolet Lumina (APV)

Bulletin No.: 91-157-6E

Date: September 30, 1991

NOTE: This bulletin cancels and supersedes Dealer Service Bulletin No. 92-02-6E, dated August 1991. The 1992 model year has been deleted, TBI engines only added and 2.8L engine included. All copies of 92-02-6E should be discarded.

VEHICLES AFFECTED

1991 Caprice and Camaro 1991 all trucks with 2.8L/4.3L, 5.0L/5.7L and 7.4L TBI engines only 1991 Lumina (APV) with 3.1L TBI engine only.

NOTE: This bulletin pertains to the 5.0L and 5.7L engine for passenger cars and 2.8L, 4.3L/3.1L, 5.0L/5.7L and 7.4L engines for light duty trucks TBI only.

VIN INFORMATION

Plant	VIN Breakpoint
Shreveport	1GCCS14ZLM8177329
Moraine	1GNCS13ZLM2211006
Pontiac	1GCCT14Z5M0149156

CONDITION

Some owners of the above vehicles may comment on a Service Engine Soon Light - Code 22 - Throttle Position Sensor low. Additional comments may include no upshift to 4th gear, no TCC, harsh transmission shifts, or poor idle quality. These conditions may be more prevalent after initial startup.

CAUSE

The above concerns may result from an intermittent electrical contact inside the Throttle Position Sensor (TPS).

CORRECTION

If any of the subject conditions are found, complete the following procedure:

Perform the normal diagnostics per Section 6E of the Service Manual.
Check TPS/ECM connectors per Dealer Service Bulletin No. 91-106-6E, dated November, 1990.
If no problems are found using the normal 6E diagnostics or the bulletin, replace the TPS with a new TPS kit, P/N 17112679 per the procedure in Section 6E of the Service Manual. The new TPS will have a yellow dot at the connector area for easier identification.

PARTS INFORMATION

Part is currently available from GMSPO.

NOTE: The lack of 4th gear, no TCC and harsh transmission shift concerns are only associated on truck applications with the HYDRA-MATIC 4L80-E (4 speed automatic) electronic transmission.

WARRANTY INFORMATION

Use applicable labor times.