ENGINE MISS, USUALLY CYL#5 GROUNDED EST HARNESS

MODELS AFFECTED: 1985-87 DE VILLE AND FLEETWOOD 1986-87 ELDORADO AND SEVILLE

Some 1985-87 De Villes and Fleetwoods or 1986-87 Eldorados and Sevilles may experience a condition of an engine miss that can usually be pinpointed to number five cylinder with an ignition scope or cylinder balance test.

This condition may be caused by the EST wire intermittently grounding against the distributor rotor hub (Figure 1). If the EST wire is chafed and contacting the rotor hub, the circuit will short to ground, thus producing a miss. To correct this condition, replace the terminal block (P/N 1987621, includes connectors and wiring).

The terminal block and harness production routing as shown in Figure 1 may not allow the wires to lay flat in the distributor housing. When installing a new terminal block, use the following procedure:

1. Connect the wires from the terminal block to the H.E.I. module.

2. Orient the terminal block and wires to the position shown in Figure 1 with the wires separated and not overlapping.

3. Rotate the terminal block 360 degrees counterclockwise (1 turn CCW) as shown in Figure 2.

4. Assemble terminal block to opening in distributor housing and install ground/hold down screw.

For warranty purposes, use labor operation J4430 at .4 hour to replace the terminal block.

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.