1989 Cadillac Deville ECM Control Unit

LARKIN600

MEMBER
1989 CADILLAC DEVILLE
V8
FWD
AUTOMATIC
110,000 MILES

The air condition nor the heat comes on in my Coupe DeVille Cadillac. On the Dash all of the digital readouts are out except the speedometer etc. The only thing I see is what appears to be half of a 2, the lower part of the number 2. Does this mean the ECM module has gone bad?

1 Reply

IMPALASS

MECHANIC
3,112 POSTS

Hello

Based off of what you have said and I am understanding what you said, there seems to be a Technical Service Bulleting out on this. I have attached it for your review.

There may be a loss of power or ground.
Bulletin .No. T-91-38
File in Group 8
Number 130
Corp. Ref. No. 018126
Date Jan. 1991

SUBJECT: VACUUM FLUORESCENCE DISPLAYS FLICKER OR GO BLANK

MODELS AFFECTED: 1985-1991 DE VILLES AND FLEETWOODS

Some 1985-1991 DeVilles and Fleetwoods may experience a condition of vacuum florescence displays flickering or going blank and the Electronic Climate Control (ECC) blower going off. This may be the result of a loss of power or ground to the Body Control Module (BCM) or an internal problem with the Digital Instrument Cluster (DIC), ECC, Fuel Data Panel (FDP), or ECC power module/blower.

Within the BCM there is a regulator which provides 16 volts for the Vacuum Fluorescence (VF) displays of the DIC, FDP, and ECC. This regulator also provides the variable voltage input to the ECC power module for blower speed control.