ELECTRONIC CONTROL PANEL AND FUEL DATA CENTER MALFUNCTION

MODELS AFFECTED: 1988-1989 DE VILLES AND FLEETWOODS

This bulletin has been revised to include new part numbers and parts information. This bulletin supersedes Serviceman Bulletin T-89-69, filed in Group 8, which should be discarded.

Some 1988-1989 DeVilles or Fleetwoods may exhibit a condition of climate control and fuel data displays blinking off then on when the dimmer switch or other high current electrical switches are used. Sometimes the displays will change settings before turning back on. (Example: With climate control set on "75/Auto" and fuel data center set on "Instant MPG", the display may blink off and come back on with "78/Front Defrost" and "Range" displayed.)

The condition is more likely to occur when the fuel data and climate control panels are warm. Headlights on for 30 minutes or more, heater air in the winter, or high sun temperatures can cause the condition.

The cause of this condition may be interference between vehicle high current circuits and the body computer 5 volt circuit to the display panels.

To repair a 1988 or 1989 vehicle, add a capacitor to the vehicle harness per the procedure described below. Do not replace the control panels.

IMPORTANT: Vehicles built late in the 1989 production year contain an improved climate control panel and fuel data center which eliminates the condition described above by including a capacitor in the panels. The improved displays also incorporate improvements to prevent sticking buttons.

The previous part numbers may be used on 1987 and prior DeVilles and Fleetwoods.

The previous part numbers should not be used on 1988 and later DeVilles and Fleetwoods.

The new part numbers may be used on all prior model DeVilles and Fleetwoods, except diesel.

The following table gives part numbers for the improved design parts:

Old P/N New P/N

Climate Control Panel With Rear Defrost, C49 1227306 16130399 Without Rear Defrost 1227307 16130400 (Parts Group 9.273)

Fuel Data Panel US/Canada 1227141/16139390 16130401 Export, MN8/Z49 16048536/16128166 16139266 (Parts Group 9.763)

Parts are currently available from GMSPO.

Adding Capacitors to Vehicle Harness:

1. Remove the center, left-hand and right hand instrument cluster trim plates as described in Section 8C of the Service Information Manual.

2. Remove the climate control panel and the fuel data center, disconnecting the wiring harness connectors.

3. Using a terminal pick, remove terminals "S" and "T" from the wiring harness connectors for the fuel data center and climate control panels.

4. Solder one capacitor, P/N 1227895, between wiring harness terminals "S" and "T" for the fuel data center. Solder another 1227895 capacitor between wiring harness terminals "S" and "T" for the climate control panel. Parts are currently available through GMSPO.

IMPORTANT:

Part Number 1227895 is a 220 to 250 micro-farad 50 volt capacitor which can be found in parts group 9.654. If the GM part number is not available, use an equivalent capacitor from an electronics supply outlet.

Be sure to solder the Positive or striped end of the capacitor to pin T. Electrolytic capacitors must be soldered in the circuit in correct polarity or they will overheat and fail.

Solder the capacitor to the removed wiring harness pins for circuits 751 and 705, not to the display panels.

If either display panel has been replaced with the new part numbers, see above, do not install a capacitor on the harness to that panel. The new part numbers already incorporate a capacitor on the circuit board.

5. Tape the capacitor leads to the wiring harness circuits 705 and 751. Be sure to completely insulate the capacitor leads.

6. Reinstall terminals into the appropriate connector.

7. Reconnect and reinstall the fuel data center and climate control panel.

8. Reinstall the instrument cluster trim plates.

For warranty purposes use Labor Operation T6370 at .8 hour.

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.