Before diagnosing an apparent ALB problem, make absolutely certain that the normal braking system is in correct working or der. Many common brake problems (dragging parking brake, seepage, etc.) will affect the ALB system. A visual check of specific system components may reveal problems creating an apparent ALB malfunction. Performing this inspection may reveal a simple failure, thus eliminating extended diagnostic time.
- Inspect the tire pressures; they must be approximately equal for the system to operate correctly.
- Inspect the brake fluid level in the reservoirs.
- Inspect brake lines, hoses, master cylinder assembly and brake calipers for leakage.
- Visually check brake lines and hoses for excessive wear, heat damage, punctures, contact with other parts, missing clips or holders, blockage or crimping.
- Check the calipers for rust or corrosion. Check for proper sliding action, if applicable.
- Check the calipers for freedom of motion during application and release.
- Inspect the wheel speed sensors for proper mounting and connections.
- Inspect the sensor wheels for broken teeth or poor mounting.
- Inspect the wheels and tires on the vehicle. They must be of the same size and type to generate accurate speed signals.
- Confirm the fault occurrence. Certain driver induced faults, such as not releasing the parking brake fully, spinning the wheels under acceleration, sliding due to excessive cornering speed or driving on extremely rough surfaces will set a fault code and trigger the dash warning light. These induced faults are not system failures but examples of vehicle performance outside the parameters of the control unit.
- Many system shut-downs are due to loss of sensor signals to or from the controller. The most common cause is not a failed sensor but a loose, corroded or dirty connector. Check harness and component connectors carefully.
Once the dash warning lamp illuminates, it will remain lit until the code (if any) is cleared. The easiest precheck of the system is simply to turn the ignition switch ON and check for the dash warning lamp to come on. Start the engine; if the warning lamp goes off after a few seconds, the system is operative with no faults found by the control unit. If the warning lamp does not extinguish, further diagnostics are required.
If the dash lamp does not come on when the ignition is turned ON , check for a failed warning bulb, an open circuit between fuse 13 on Prelude or fuse 1 on Accord and the instrument cluster, an open in the blue/red wire from the instrument cluster to the ALB control unit, or a faulty ground in the attachment of the control unit to the body.
The dash warning lamp may remain on after the engine is started. Common causes are loose or weak connection of the ALB harness to the control unit, faulty Accord ALB B2 fuse or Prelude No. 27 fuse, or an open circuit in the white wire between ALB 2 or 27 fuse and the control unit. The problem may also be caused by an open circuit between Prelude fuse 17 or Accord fuse 8 and the fail-safe relays, or an open/shorted circuit in the yellow/green wire to the fail-safe relays. Additionally, check the white/blue wire between the alternator and the control unit for an open circuit. The blue/red wire from the gauge assembly to the control unit should also be checked for shorted or open conditions.
The dashboard warning lamp will light when there is insufficient battery voltage to the control unit. Once proper voltage is restored, the light will extinguish and the system will work normally.
The electronic control unit for the ALB system possesses self-diagnostic capabilities similar to the fuel injection system. If a signal is seen to be out of range, either high or low, the controller will note the fault and trigger the ALB dash warning lamp. A fault code is stored in the system memory to identify the faulty signal.
Diagnosis of the system requires Honda's ALB checker, a sophisticated test tool available at dealerships. In the event that the warning lamp on your car stays on during normal operation, check the simple things carefully. The most frequent causes of signal error or loss are not the most difficult to investigate.
If the problem is not solved through your efforts, take the car to your Honda dealer for a system inspection.