SERVICE ENGINE SOON LIGHT OR GEAR SELECT PROBLEMS

SUBJECT: "SERVICE VEHICLE SOON" LIGHT OR "GEAR SELECT PROBLEM" CODE E91/E091 (REPLACE PARK NEUTRAL SWITCH)

(Revised to Update Information)

VEHICLES AFFECTED: 1991-92 CADILLAC C, E, K CARS

Some vehicles may experience a "Service Vehicle Soon" light or a "Gear Select Problem" message (Eldorado/Seville) with a code E91 or E091 ... This code may result in inoperative cruise control. The vehicle continues to start only in park or neutral.

These conditions may be caused by a neutral start backup switch, (or a loose or corroded engine ground).

To repair this condition use the following procedure:

1. Enter ECM diagnostics and record the code E91 snapshot data. Pay particular attention to parameter L.0.7 on DeVilles and Fleetwoods and ED10 on Eldorados and Sevilles. If the code data indicates battery voltage below 13.0 with the engine running, proceed to step 2. If the voltage is 13.0 or above, proceed to step 3.

2. Remove and clean the ground stud by the starter. Install a star washer, P/N 11501869 for Eldorados and Sevilles or P/N 11504332 for DeVilles and Fleetwoods, on both sides of the stud to engine block. For location on DeVilles and Fleetwoods refer to Figure 1, for Eldorados and Sevilles refer to Figure 2.

3. On all 1991 vehicles and 1992 vehicles prior to VIN breakpoint 609951 for Eldorados, 812955 for Sevilles, and 276298 for DeVilles and Fleetwoods, replace the neutral start backup switch with P/N 1994335 for DeVilles and Fleetwoods and P/N 1994334 for Eldorados and Sevilles. See Section 7Al in the appropriate Service Information Manual for replacement procedure.

Vehicles built after the breakpoint are equipped with the new parts. Refer to code E91 diagnosis in Section 6EA of the appropriate Service Information Manual for diagnosis.

NOTE: Do not adjust the shift indicator needle linkage (Labour Operation K5243) to correct a code E91.

For vehicles repaired under warranty use:

Operation Description Operation Number Vehicle Series --------------------- ---------------- -------------- C E K Ground Repair .5 .5 .5

Switch, Park/Neutral Replace J6383 1.1 .4 .4

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.