BENDIX BW1396 Fiche De Données

•   All genuine Bendix replacement parts are manufactured to meet original 

OE specifications to guarantee quality,  reliability and proper operating 
performance.

•   Rely on genuine Bendix replacement parts to keep your Air Brake System 

operating efficiently.

•   With thousands of Authorized Bendix parts outlets across North America, 

you’re never far from quality genuine Bendix replacement parts.

www.foundationbrakes.com

NOTE:  A leak detector or soap solution will aid in locating the faulty component.

1.  Supply lines and fi ttings

2.  Low pressure indicator(s)

3.  Service brake relay valve(s) 

4.  Spring brake relay valve (where applicable)

5.  Dual brake valve

6.  Trailer hand control valve

7.  Parking control valve

8.  System safety valve(s) in the supply reservoir and/or air dryer 

9.  Governor (may be mounted on the air dryer as illustrated, on the compressor, or remotely)

10. Compressor discharge line 

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

1. Make and hold brake application. When ignition power is applied, each 

modulator solenoid is briefl y energized. If  the air system is fully charged and 
the service brake pedal is depressed during ignition, the modulator creates a 
single, sharp audible “chuff” of  air pressure. The modulators are energized in 
a certain pattern, as follows: right front, left front, right rear, left rear. This test 
is performed only when the vehicle is stationary (if  the vehicle moves the chuff  
test will not be performed).

NOTE:  The EC-60

™

 controller will perform a PMV chuff  test on all installed modulators in the following order:

  1.  Steer Axle Right PMV

  2. Steer Axle Left PMV

  3.  Drive Axle Right PMV

  4. Drive Axle Left PMV

  5. Additional Axle Right PMV

  6. Additional Axle Left PMV

  7. Drive Axle TCV

 The pattern will then repeat itself.

See appropriate Service Data Sheet for repairs.

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

1. Manually operate the park control, yellow button valve, and note that parking 

brakes apply and release promptly as the control valve button is pulled out and 
pushed in.

1. Manually operate the tractor protection control valve (trailer supply valve usually 

red octagonal button).  Note that trailer brakes apply and release promptly as the 
control button is pulled out and pushed in.

2. Manually operate system park control (usually yellow diamond button) and note 

all parking brakes (tractor and trailer) apply promptly.

1.  Dented or kinked lines

2.  Improperly installed hose fi tting

3.  A faulty quick release valve or spring brake control valve

4.  Damaged or improperly installed Spring Brake Chamber and/or Service Chambers

5.  Foundation Brake component binding, improper installation and/or lack of  lubrication.

1.  Tractor protection control

2.  Trailer spring brake valve

3.  Damaged spring brake chamber and/or service chambers

4.   Foundation brake component binding, improper installation and/or lack of  lubrication

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

1.  Drain the front axle or secondary reservoir to 0 psi.

A.  The rear axle or primary reservoir should retain most of  its pressure.

B.   On combination vehicles, the trailer air system should remain charged.

C. Tractor and trailer brakes should not apply automatically.

2.  With no air pressure in the front axle reservoir, make a brake application.

A. Rear axle brakes should apply and release when application is released.

B. On combination vehicles the trailer brakes should also apply and release 

when application is released.

C. The stop lamps should light and go off  when the application is released.

3. “Pop” Pressure Vehicle Test Procedure

Note: Bendix is not aware of  any federal legislation that specifi es the pressure at which the YELLOW 
parking brake control valve must automatically “trip” to apply the vehicle parking brakes.  This includes the 
Federal Motor Carrier Safety Regulations (FMCSR) for in-use vehicles, the CVSA out-of-service criteria, 
and the Federal Motor Vehicle Safety Standards (FMVSS) for newly manufactured vehicles.  Although 
the “trip” pressure for the parking brake control valve is not stipulated for in-use or newly manufactured 
vehicles, a parking brake control valve “trip” pressure of  20-40 psi is currently (02/2009) specifi ed as 
part of  the Commercial Driver License in the CDL Manual.  The CDL Manual is not consistent with the 
regulations cited above.  See Bulletin TCH-003-051.                                                          

           

continued . . .

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

1. Make and hold an 80-90 psi brake application. This can be accomplished by 

using the BVA-85

™

 brake valve actuator.  If  the vehicle is not equipped with 

a BVA-85

™

 brake valve actuator, an assistant should be used to maintain a 

constant application during these tests.

2. Allow pressure to stabilize for 1 minute; then begin timing for 2 minutes while 

watching the dash gauges for a pressure drop.

A. Pressure Drop: Single Vehicle (A 4 psi drop within 2 minutes is allowable for 

either service reservoir)

B. Pressure Drop: Tractor/Trailer (A 6 psi drop within 2 minutes is allowable for 

either service reservoir)

C. Pressure Drop: Tractor/2 Trailers (An 8 psi drop within 2 minutes is allowable 

for either service reservoir)

3. Check brake chamber push rod travel (refer to chart for allowable tolerances).  

With the parking brakes released and service brakes applied with 80 to 90 psi of  
air pressure to the service chambers.
 

 12 

1-3/8” 

1-3/4” 

 16 

1-3/4” 

2” 

 

 20 

1-3/4” 

2” 

 

 24 

1-3/4” 

2” 

 

  24 (Max Stroke) 

- 

2-1/2” 

 

 30 

2” 

2-1/2”

4. Check the angle formed between the brake chamber push rod and slack 

adjuster arm. It should be equal to or slightly less than 90° in the applied position 
(80-90 psi) and the same across the axle.

NOTE: A leak detector or soap solution will aid in locating the faulty component.

1.  Loose service lines and fi ttings 

2.  Trailer control valve

3. Stoplight switch

4.  Spring brake chamber, service chamber and/or brake chamber diaphragms

5.  Tractor protection valve

6.  Service brake relay valves 

7.  Dual brake valve

8.  Inverting relay spring brake control valve (where applicable – usually found on the spring brake relay 

valve) straight trucks and buses

9.  Double check valve

.

CAUTION:  If the brake chamber push rod travel exceeds   the  allowable  stroke,  identify  and  correct  the 
root cause of the excess stroke.  Do not make manual adjustments of an automatic slack adjuster once 
it can no longer automatically adjust the brakes.  Manual adjustment DOES NOT fi x the underlying wheel 
end adjustment.  As soon as possible, have the vehicle inspected by a qualifi ed technician or consult the 
manufacturer’s troubleshooting guidelines to fi nd and fi x the problem.





1. Drain all the reservoirs to 0 psi.

2. Start the engine and run at fast idle.  The low pressure warning should be 

on.  Note: on vehicles equipped with ABS, the warning lamp will also come 
on momentarily when the ignition is turned on.  On some systems, such as the 
AD-IS

®

 dryer system (illustrated), reservoirs may not fi ll simultaneously and one 

reservoir may fi ll to 110 psi before the other starts to fi ll.  

3. Low pressure warning; dash warning lamp should go off  above 60 psi.

4. Build up time; pressure should build from 85-100 psi within 40 seconds.

5. Governor cut-out; cuts out at the correct pressure, usually 125-135 psi.

6. Governor cut-in; reduce the service air pressure to governor cut-in. The 

difference between cut-in and cut-out pressure must not exceed 30 psi.

1.  Check the warning lamp wiring.

2.  Check the warning lamp bulb.

3.  Repair or replace the buzzer, bulb or low pressure warning switch(es).

1.  Repair, replace or adjust the governor as necessary after ensuring the compressor unloader 

mechanism is operating correctly.

1.  Check the dash gauge with test gauge known to be accurate.

2.  Repair or replace the faulty low pressure indicator switch.

1.  Examine the compressor air inlet fi lter and inlet line checking for restrictions, damage or wear.  Clean 

or replace the fi lter or inlet line as necessary.

2.  Check the  compressor discharge port and line for excessive carbon. Clean or replace the discharge 

line as necessary.  If  there is carbon, fi nd the cause of  the excessive heat.

3.  With the system fully charged and governor in the unloaded mode, listen at the compressor inlet for 

leakage. If  leakage can be heard, remove the unloaders and repair or replace as necessary.

For additional information refer to video Assessing Air Brake System Air Leakage 

(BW2327 - CD)





1. Allow the air pressure to stabilize for at least 1 minute.

2. Observe the dash gauge pressures for 2 minutes and note any pressure drop.

A. Pressure Drop: Single Vehicle (A 4 psi drop within 2 minutes is allowable for 

either service reservoir)

B. Pressure Drop: Tractor/Trailer (A 6 psi drop within 2 minutes is allowable for 

either service reservoir)

C. Pressure Drop: Tractor/2 Trailers (An 8 psi drop within 2 minutes is allowable 

for either service reservoir)





3. 

“Pop” Pressure Vehicle Test Procedure (Continued)

A. Install an accurate “shop standard” pressure gauge in the secondary service 

reservoir.

B. Build pressure in the service reservoirs until the compressor cut-out is 

reached, shut the engine off.

C. Fully open the manual drain valve on the primary service reservoir allowing 

the reservoir to drain completely.

D. Open the secondary reservoir’s manual drain valve creating a bleed rate of  

approximately 20-50 psi/min.

E. Monitor the pressure gauge noting the pressure at which the parking control 

automatically “pops”.  This is not a Federal requirement - See Note in 
previous column.

4.   For Towing Vehicles Only - Test the tractor protection valve feature

 

A. Charge the air system to governor cut-out.

B. Disconnect the service or control (blue) line to the trailer.

C. Take care to restrain the service coupling and direct fl ow safely away while 

making and holding a full service brake application via the foot valve.

D. As the service application is vented through the open gladhand, the service 

system pressure drops until the tractor protection control (red) valve trips and 
shuts off  the leak through the open coupling.  This leak must be shut off.

E. Record the pressure in the service reservoirs. Disconnect the trailer supply 

coupling to verify that the supply or emergency (red) coupling has been 
vented to atmosphere, thereby activating the trailer emergency feature.

5.  Close the drain cocks, recharge the system and drain the rear axle primary 

reservoir to 0 psi.

A. The front axle reservoir should retain most of  its pressure.

B. On combination vehicles the trailer air system should remain charged.

6. With no air pressure in the rear axle reservoir, make and release a brake 

application. 

A. Front axle brakes should apply and release.

B. On combination vehicles the trailer brakes should also apply and release. 

C. If  the vehicle is equipped with a spring brake modulating valve, typically found 

on trucks, towing trucks and buses, the rear axle brakes should also apply 
and release by exhausting spring brake air.

1. Fittings

2.  Kinked hose or tubing

3.  Pressure protection valves

4.  Double check valves

5.  Tractor protection valve

6.  Tractor protection control valve

7.  Parking control valve

8.  Relay valves (antilock modulators)

9.  Trailer spring brake control valve

10. Inverting relay spring brake control valve 

(optional) straight trucks and buses

BW1114  Quick Reference Catalog
BW1231 

BW1231  Air Brake System Troubleshooting Wallchart version of this piece.
BW1555  Brake Balance Procedure
BW2780  Troubleshooting Bendix

®

 ESP

®

 Stability System Wallchart

BW2786  Troubleshooting Bendix

®

 ESP

®

 Stability System

BW5057  Air Brake Handbook
SD-13-4863  Service Data Sheet for EC-60

™

 ABS/ATC Standard & Premium Controllers

BW1396  ©  2009 Bendix Commercial Vehicle Systems LLC, a member of  the Knorr-Bremse Group • All Rights Reserved • 08/09 • Printed in U.S.A.