ENGINE QUITS, WHINE/WHISTLE INTERMITTENT TROUBLE CODES

Vehicles Affected: 1985 Cadillac "C" Models

A number of false intermittent trouble codes and/or engine quits at closed throttle may occur on some 1985 FWD-'C' vehicles when changing ECC blower speeds from low to high or when changing ECC operating modes from 'OFF' to another mode. The cause is an unwanted voltage variation (oscillation) from the ECC power module, which transmits through the vehicles wiring, affecting various electronic components.

This condition can sometimes be heard as a high pitched whine or whistle in the right side of the instrument panel at low blower speed and with the radio off, and appears to be more likely to occur when the power module is hot. When this condition occurs, some cars may have static coming from the car's radio which stops when the ECC mode is changed to 'OFF'.

Although a number of false intermittent ECM or BCM trouble codes may occur, the trouble codes that are most likely to occur as a result of this condition are:

ECM Codes - E13, E18, E20, E44, E47, E52, E53

BCM Codes - F30, F31, F32.

A power module production change was made effective at B.P. 234578, to eliminate this condition. The new power module (P/N 16049206) can be identified, without removing it from the evaporator assembly, by a green tag on the top surface of the unit.

To diagnose this condition, check:

1. If the intermittent trouble code or driveability condition can be duplicated when changing ECC blower speeds from low to high or when changing ECC operating modes from 'OFF' to another mode.

2. For an audible whine coming from the power module on the right side of the I.P. at low blower speed.

If either can be duplicated, the power module should be replaced with P/N 16049206. Availability of this power module will be limited initially and it may be necessary to order on a V.I.P. basis.

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.