37 90 ... Troubleshooting On Level Control System

Faults marked with * can be limited with BMW Diagnosis System.

1. Height setting not O.K. 
   HEIGHT SETTING NOT O.K.
   
   

   Fault	Cause	Remedy
   Vehicle too low when stationary but rises to correct height when vehicle is started.	a) Stationary for too long b) Large temperature drop while vehicle stationary c) Line/air tank defective d) Air supply unit defective e) Both air springs defective f) One of lines (to air springs/air reservoirs) on both sides defective	a) No fault (system-related) b) No fault (system-related) c) Check lines (in visible area), air tank and screw connections (first on distributor block and air tank, then on pneumatic spring) with leak tester spray and replace if necessary. d) Replacing air supply unit e) Replace air springs f) Replace lines
   One side of vehicle too low when stationary, but rises again after vehicle starts.	a) Line/air tank defective b) Air supply unit defective c) Air spring defective d) Line (to air spring/air reservoir) defective	a) Check lines (in visible area), air tank and screw connections (first on distributor block and air tank, then on pneumatic spring) with leak tester spray and replace if necessary. b) Replacing air supply unit c) Replace air spring d) Replace line
   * One side of vehicle too high (does not lower in response to control unit).	a) Height setting sensor mechanically defective (bracket, control rod bent) b) Lines interchanged c) A line is blocked d) Air supply unit defective	a) If necessary, replace height setting sensor, bracket and control rod b) Connect lines of same color c) Unfasten line on distributor block, check for escaping air and replace if necessary d) Replacing air supply unit
   * Both sides of vehicle always too low. If the vehicle was driven in this condition, refer to 37 00 ... NOTES ON AIR SPRING SYSTEM	a) Overload b) Failsafe on air supply unit defective c) Relay defective d) Air supply unit defective e) Line/air tank defective f) Both height setting sensors mechanically defective (bracket, control rod bent) g) Both air springs defective h) One of lines (to air springs/air reservoirs) on both sides defective	a) Partially unload vehicle b) Replace failsafe c) Replace relay d) Replacing air supply unit e) Check lines (in visible area), air tank and screw connections (first on distributor block and air tank, then on pneumatic spring) with leak tester spray and replace if necessary. f) If necessary, replace height setting sensor, bracket and control rod g) Replace both air springs h) Replace lines
   * Vehicle does not rise in response to loads	a) Overload b) Failsafe on air supply unit defective c) Air supply unit defective d) Both height setting sensors mechanically defective (bracket, control rod bent) e) Lines on both sides blocked or defective	a) Partially unload vehicle b) Replace failsafe c) Replacing air supply unit d) If necessary, replace height setting sensor, bracket and control rod e) Blow out lines and replace if necessary
   * One side of vehicle too low. If the vehicle was driven in this condition, refer to 37 00 ... NOTES ON AIR SPRING SYSTEM	a) Height setting sensor mechanically defective (bracket, control rod bent) b) Line/air tank defective c) Air supply unit defective d) Air spring defective e) Line defective	a) If necessary, replace height setting sensor, bracket and control rod b) Check lines (in visible area), air tank and screw connections (first on distributor block and air tank, then on pneumatic spring) with leak tester spray and replace if necessary c) Replacing air supply unit d) Replace air spring e) Replace line
   * Vehicle only rises on one side in response to load. If the vehicle was driven in this condition, refer to 37 00 ... NOTES ON AIR SPRING SYSTEM	a) One-sided loading b) Height setting sensor mechanically defective (bracket, control rod bent) c) Line/air tank defective d) Air supply unit defective e) Air spring defective f) Line defective	a) Partially unload vehicle b) If necessary, replace height setting sensor, bracket and control rod c) Check lines (in visible area), air tank and screw connections (first on distributor block and air tank, then on pneumatic spring) with leak tester spray and replace if necessary d) Replacing air supply unit e) Replace air spring f) Replace line
   *Both sides of vehicle too high (does not lower in response to control)	a) Control unit still in "Transport" mode b) Air supply unit defective c) Lines on both sides blocked	a) Change mode with BMW Diagnosis System b) Replacing air supply unit c) Blow out lines and replace if necessary

2. Control times not O.K. 
   CONTROL TIMES NOT O.K.
   
   

   Fault	Cause	Remedy
   * Vehicle rises too slowly	a) Overload b) Battery voltage too low c) Air supply unit defective d) Lines defective or blocked	a) Partially unload vehicle b) Charge battery/start engine c) Replacing air supply unit d) Check lines with leak tester spray or blow out and replace if necessary
   * Vehicle lowers too slowly	a) Air supply unit defective b) Line blocked	a) Replacing air supply unit b) Blow out lines and replace if necessary

3. Drive characteristics not O.K. 
   DRIVE CHARACTERISTICS NOT O.K.
   
   

   Fault	Cause	Remedy
   * Vehicle height control operates frequently while vehicle in motion	a) System leaking	a) Refer to HEIGHT SETTING NOT O.K.

4. Compressor 
   COMPRESSOR
   
   

   Fault	Cause	Remedy
   * Compressor ran significantly longer than 2 minutes	a) Air supply unit defective	a) Replacing air supply unit
   Compressor runs loudly	a) Air supply unit defective	a) Replacing air supply unit