Data Displays
WARNING: This page is about a different car, the 1989 Cadillac Allante. However, it is still accessible from the selected car via links, so may be relevant.
When trouble shooting a malfunction, data displays can be used to compare vehicle with problems to a vehicle which is functioning properly. The following are a summary of each parameter for Body Computer Module.
- BD20 - COMMANDED BLOWER VOLTAGE
Is read in volts from -2.9 to 18.0 Volts. - BD21 - COOLANT TEMPERATURE
Coolant temperature is displayed in degrees Celsius (°C) from -40 to 151. This value is sent from the ECM to BCM. If this circuit malfunctions as determined by ECM, the ECM will send BCM a "Failsoft" value for display. - BD22 - COMMANDED AIR MIX DOOR POSITION
Is displayed in percent (%). A value close to 0% represents a max cold air mix and a value close to 100% represents a max heat air mix. - BD23 - ACTUAL AIR MIX DOOR POSITION
Displayed in percent (%). This value should follow commanded air mix door position (BD22) when BD22 is between 20 and 95. - BD24 - AIR DELIVERY MODE
The is displayed as a number from 0 to 7. Each number is a code which represents the following air delivery modes: 0 = MAX A/C, 1 = A/C, 2 = Intermediate, 3 = Heater, 4 = OFF, 5 = Normal Purge, 6 = Cold Purge, 7 = Front Defog. - BD25 - IN-CAR TEMPERATURE
Is displayed in degrees Celsius (°C), from -40 to 102. - BD26 - ACTUAL OUTSIDE TEMPERATURE
Is displayed in degrees Celsius (°C), from -40 to 102. This value represents actual sensor temperature and is not restricted by the features used to minimize engine heat affects on the customer display value. - BD27 - HIGH SIDE TEMPERATURE
Is displayed in degrees Celsius (°C) from -40 to 215. - BD28 - LOW SIDE TEMPERATURE
Is displayed in degrees Celsius (°C) from -40 to 102. - BD32 - SUNLOAD TEMPERATURE SENSOR
Is displayed in degrees Celsius (°C) from -40 to 102. - BD40 - ACTUAL FUEL LEVEL
Actual fuel level is read in gallons between zero to 19.0 (display can read to 25.0). This value represents actual sensor position and is not restricted by features used to eliminate fuel slosh affects on customer display value. - BD41 - PRND321
PRND321 is displayed in a 4 digit binary number P=0110, R=0011, N=1010, 3=0000, 2=0101, 1=1100. - BD42 - DIMMING POT
Dimming pot is displayed in percent (%). A value close to 0% represents maximum dimming, and a value close to 100% represents maximum brightness. - BD43 - TWILIGHT DELAY POT
Is displayed in percent (%). A value close to 0% represents minimum delay time and a value close to 100% represents maximum delay time. - BD44 - TWILIGHT PHOTOCELL
Is displayed in percent (%). A value close to 0% represents daylight and value close to 100% represents darkness. - BD50 - BATTERY VOLTAGE
Battery voltage is read in volts between zero and 16.3. - BD51 - GENERATOR FIELD
Generator field is displayed in percent (%). A value close to zero % represents minimum regulator on time, and a value close to 100% represents maximum regulator on time. - BD60 - VEHICLE SPEED
Vehicle speed is displayed in miles per hour (MPH) from zero to 159. - BD61 - ENGINE SPEED
Engine speed is displayed in RPM from zero to 6375. - BD71 - OIL PRESSURE
Oil pressure value is displayed in pounds per square inch (PSI). This value should be zero with engine off, and reflect the true oil pressure with engine running. - BD98 - IGNITION CYCLE
Is the number of times that the BCM has been turned "OFF" since a BCM trouble code was last detected. After 100 ignition cycles without any malfunction being detected, all BCM codes are cleared. - BD99 - BCM PROM ID
Is used to identify what PROM is currently used in the BCM.