BCM Data Displays

Data displays are operated as defined under SELECTING TEST  . When troubleshooting a malfunction, the BCM data display can be used to compare the vehicle with problems to a vehicle which is functioning properly. A brief summary of each parameter is provided below:

1. BD20 - COMMANDED BLOWER VOLTAGE
   
   Is read in volts from -2.9 to 18.0 Volts. BD20 is the blower voltage that the BCM is requesting of the power module.
2. BD21 - COOLANT TEMPERATURE
   
   Coolant temperature is displayed in degrees Celsius (°C) from -40 to 151. BD21 is the coolant temperature sent from the ECM to the BCM. If the coolant temperature sensor circuit malfunctions causing ECM code EO14 or EO15 to set. See SELF-DIAGNOSTICS -- ALLANTE article in ENGINE PERFORMANCE. The ECM will send the BCM a "Failsoft" value for display.
3. BD22 - COMMANDED AIR MIX DOOR POSITION
   
   Is displayed in percent (%). BD22 is the air mix door position that the BCM is requesting of the programmer. A value close to 0% represents a Max cold air mix and a value close to 100% represents a Max heat air mix.
4. BD23 - ACTUAL AIR MIX DOOR POSITION
   
   Displayed in percent (%), from 0 to 100. BD23 should follow the commanded air mix door position (BD22) when BD22 is between 20 and 95.
5. BD24 - AIR DELIVERY MODE
   
   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.
6. BD25 - IN-CAR TEMPERATURE
   
   Is displayed in degrees Celsius (°C), from -40 to 102. BD25 is the interior temperature reading of the vehicle, that is received at the BCM from a sensor mounted in the I/P, to the left of center.
7. BD26 - ACTUAL OUTSIDE AIR TEMPERATURE
   
   Is displayed in degrees Celsius (°C), from -40 to 102. BD26 is the actual outside air temperature reading, around the vehicle, that is received at the BCM from a sensor mounted in a protective housing just behind the radiator grille.
8. BD27 - HIGH SIDE TEMPERATURE
   
   Is displayed in degrees Celsius (°C) from -40 to 215. BD27 is the high side temperature reading, of the A/C refrigerant, that is received by the BCM from a sensor mounted in the liquid refrigerant line between the condenser and the orifice tube.
9. BD28 - LOW SIDE TEMPERATURE
   
   Is displayed in degrees Celsius (°C) from -40 to 102. BD28 is the low side temperature reading, of the A/C refrigerant, that is received by the BCM from a sensor mounted in the refrigerant line between the orifice tube and the evaporator.
10. BD32 - SUNLOAD TEMPERATURE SENSOR
    
    Is displayed in degrees Celsius (°C) from -40 to 102. BD32 is the sun load temperature reading, of the heat load induced in the vehicle by the sun, that is received by the BCM from a sensor mounted under the defroster grille, center position, at the base of the windshield.
11. BD40 - ACTUAL FUEL LEVEL
    
    Actual fuel level is read in gallons between zero to 19.0 (display can read to 25.0). BD40 is the actual fuel level reading, of the fuel in the fuel tank, that is received by the BCM from a sensor mounted in the fuel tank.
12. BD41 - PRND321 SENSOR
    
    PRND321 is displayed in a 4 digit binary number P=0110, R=0011, N=1010, 3=0000, 2=0101, 1=1100. BD41 is the PRND321 code reading that is received by the BCM from a position switch sensor mounted on the transaxle.
13. BD42 - DIMMING POT
    
    Dimming pot is displayed in percent (%) FROM 0 to 100. BD42 is the dimming pot reading, of the I/P light intensity control, that is received by the BCM from a potentiometer mounted in the headlight (left) switch assembly. A value close to 0% represents maximum dimming and a value close to 100% represents maximum brightness.
14. BD43 - TWILIGHT DELAY POT
    
    Is displayed in percent (%) from 0 to 100. BD43 is the twilight delay pot reading, of the twilight sentinel, that is received by the BCM from a potentiometer mounted above the headlight switch on the I/P. A value close to 0% represents minimum delay time and a value close to 100% represents maximum delay time.
15. BD44 - TWILIGHT PHOTOCELL
    
    Is displayed in percent (%) from 0 to 100. BD44 is the twilight photocell reading, of the twilight sentinel, that is received by the BCM from a photo-voltaic sensor mounted in the front defroster grille. A value close to 0% represents daylight and a value close to 100% represents darkness.
16. BD50 - BATTERY VOLTAGE
    
    Battery voltage is read in volts between zero and 16.3. BD50 is the battery voltage reading that is received by the BCM from the central power supply.
17. BD51 - GENERATOR FIELD
    
    Generator field is displayed in percent (%) from 0 to 100. BD51 is the generator field reading, of the percent "ON" time of the regulator, that is received by the BCM from the generator. A value close to 0% represents minimum regulator "ON" time and a value close to 100% represents maximum regulator "ON" time.
18. BD60 - CAR SPEED
    
    Car speed is displayed in miles per hour (MPH) from zero to 159. BD60 is the car speed reading that is received by the BCM from the vehicle speed sensor mounted on the transaxle.
19. BD61 - ENGINE RPM
    
    Engine speed is displayed in RPM from zero to 6375. BD61 is the engine speed reading, in revolutions per minute, that is received by the BCM from the ECM.
20. BD71 - OIL PRESSURE
    
    Oil pressure value is displayed in pounds per square inch (PSI) from 0 to 85.0. BD71 should be zero with the engine off, and reflect the true oil pressure with the engine running.
21. BD98 - IGNITION CYCLE
    
    Is displayed in number of ignition cycles, from 0 to 100. BD98 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.
22. BD99 - BCM PROM ID
    
    Is displayed from 0 to 9999. BD99 is used to identify what PROM is currently used in the BCM.