See Figures 1 and 2
Diagnosis of the ABS system consists of 3 general steps, performed in order. First is the visual or preliminary inspection, including inspection of the basic brake system, it is always required before any other steps are taken. Next, diagnosis of the system is then made by a careful analysis of the ANTI-LOCK warning lamp display during start-up and operation. Third, the warning lamp diagnosis via the use of the Multi-Use Tester will direct the use of further charts.
The ABS systems may be checked with the Multi-Use Tester, allowing diagnostic codes to be output. Connect the tester properly; the system will enter diagnostic mode and prompt the operator through the diagnostic procedures.Visual Inspection
Before diagnosing an apparent ABS problem, make absolutely certain that the normal braking system is in correct working order. Many common brake problems (dragging lining, seepage, etc.) will affect the ABS system. A visual check of specific system components may reveal problems creating an apparent ABS malfunction. Performing this inspection may reveal a simple failure, thus eliminating extended diagnostic time.
- Inspect the brake fluid level in the reservoir.
- 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 caliper pistons for freedom of motion during application and release.
- Inspect the wheel speed sensors for proper mounting and connections. Make certain the sensor wiring is properly routed and retained in all clips.
- Inspect the toothed 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. Check also for approximately equal tire pressures.
- Confirm the fault occurrence with the operator. Certain driver induced faults may cause dash warning lamps to light. Excessive wheel spin on low-traction surfaces or high speed acceleration may also set fault codes and trigger a warning lamp. These induced faults are not system failures but examples of vehicle performance outside the parameters of the controller.
- The most common cause of intermittent faults is not a failed sensor but a loose, corroded or dirty connector. Incorrect installation of the wheel speed sensor will cause a loss of wheel speed signal. Check harness and component connectors carefully.
The diagnostic connector is located under the left side dashboard, in the kick panel. Stored diagnostic codes may be retrieved using a suitable scan tool as follows:
- With the ignition OFF , connect the scan tool to the data link connector in the left side kick panel.
- Turn the ignition ON and select the ABS diagnostics on the scan tool. Once in the diagnostic mode the anti-lock system becomes inoperative and the ABS light remains illuminated.
- If the system does not enter into diagnostics, inspect the ECU power circuit and wire harness between the ECU and data link terminals.
- Read the ECU memory stored codes.
- Erase the codes stored in the ECU memory.
- Turn the ignition OFF and disconnect the scan tool. Test drive the vehicle.
- If the vehicle goes into the fail safe mode during the test drive and diagnostic codes are stored, refer to the trouble code diagnostic charts.
The anti-lock system memory codes can only be cleared using a scan tool. Disconnecting the negative battery cable or turning OFF the ignition switch will not clear the system memory.
Refer to the manufacturers scan tool instructions. If the ECU is in the fail-safe mode and a component malfunction exists.
FILLING THE SYSTEM
The brake fluid reservoir is part of the normal brake system and is filled or checked in the usual manner. Always clean the reservoir cap and surrounding area thoroughly before removing the cap. Fill the reservoir only to the FULL or MAX mark; do not overfill. Use only fresh DOT 3 brake fluid from unopened containers. Do not use any fluid containing a petroleum base. Do not use any fluid which has been exposed to water or moisture. Failure to use the correct fluid will affect system function and component life.
BLEEDING THE SYSTEM
The brake system must be bled any time a line, hose or component is loosened or removed. Any air trapped within the system can affect pedal feel and system function. Bleeding the complete system including the modulator assembly requires the use of the Hyundai Multi-Use Tester (MUT) to cycle all of the build/decay and isolation valves of the hydraulic modulator. Make certain the fluid level in the reservoir is maintained at or near correct levels during bleeding operations. Use an inline filter when adding new brake fluid to the master cylinder reservoir. To bleed the system proceed as follows:
- Bleed the normal brake system using the standard procedure. Bleed the wheel circuits in the following order: left rear, right front, right rear and left front.
- Connect the MUT to the diagnostic connector located under the dash near the dash.
- Turn the ignition switch ON , but do not start the engine.
- Connect a clear vinyl tube to the bleeder screw to be opened and place the other end in a clear container partially filled with new brake fluid.
- Depress the brake pedal lightly and use the MUT to actuate the appropriate valves. When each valve cycles, fluid from the respective fitting will emerge. Proceed with bleeding each of the 4 modulator circuits in the order shown.
- The pedal will drop slightly as the valve is cycled. If pedal drops completely, close the bleed valve and re-apply light pressure to the pedal.
- When air bubbles no longer emerge from the bleed port, close the bleeder and proceed to the next port.
- Check and add brake fluid to the reservoir as needed.