Anti-Lock Brake System - Introduction Acura SLX I

MODEL IDENTIFICATION

MODEL IDENTIFICATION

DESCRIPTION

The Anti-Lock Brake System (ABS) operates on all 4 wheels. ABS operation is controlled by the Electronic Brake Control Module (EBCM). The EBCM receives input signals from wheel speed sensors to monitor wheel speed. If EBCM determines a wheel is about to lock, hydraulic pressure is adjusted to maintain optimum braking. ABS system consists of an EBCM, "G" sensor/accelerometer, hydraulic unit, Brake Pressure Modulator Valve (BPMV), ABS warning light, wheel speed sensors, differential speed sensor and Vehicle Speed Sensor (VSS). Not all components are common to each model. Components vary depending on model and application. See COMPONENT LOCATIONS.

Note. For additional information on brake system, see appropriate DISC & DRUM article. For models with rear ABS, see REAR ANTI-LOCK - PASSPORT, RODEO & SLX article.

ABS WARNING LIGHT

Amber ABS warning light is located on instrument cluster. ABS warning light will illuminate during engine start for about 3 seconds. If ABS warning light remains illuminated, a malfunction is present. Anti-lock braking function is disabled until system is repaired.

BRAKE PRESSURE MODULATOR VALVE (HOMBRE)

Brake Pressure Modulator Valve (BPMV) is located in engine compartment, and regulates hydraulic pressure in brake system during ABS operation. BPMV consists of 3 channels; right front, left front and rear brakes. Each channel consists of an isolation valve and dump valve. Front channels share a low pressure accumulator, attenuator and pump. Rear channel also has these components and controls both rear wheels simultaneously.

DIFFERENTIAL SPEED SENSOR

Differential speed sensor is used on 2WD Passport, Rodeo and SLX. Sensor is of the variable reluctance type and is mounted on rear differential in close proximity to an internal toothed ring. As teeth pass by sensor head, an AC voltage is produced. Sensor signal frequency increases as ring rotation speed increases.

ELECTRONIC BRAKE CONTROL MODULE (EBCM)

EBCM receives inputs from wheel speed sensors, VSS, "G" sensor/accelerometer and brakelight switch. EBCM determines if a wheel is beginning to lock. If a locking condition is detected, EBCM sends a signal to hydraulic unit or BPMV, adjusting brake pressure to provide for maximum braking without wheel lock.

"G" SENSOR/ACCELEROMETER (4WD)

"G" sensor/accelerometer is mounted under center console, and is used to detect vehicle deceleration during 4WD operation. This allows ABS control to compensate for changes in road surface condition.

HYDRAULIC UNIT (PASSPORT, RODEO, SLX & TROOPER)

Hydraulic unit components consist of motor, plunger pump, solenoid valve and check valve. A relay box containing motor relay and valve relay is installed on outside of hydraulic unit. Hydraulic unit is controlled by inputs from EBCM.

Check Valve

Check valve controls brake fluid flow.

Motor

Motor operates plunger pump based on EBCM signal.

Plunger Pump

Plunger pump supplies brake fluid to master cylinder from reservoir.

Solenoid Valve

Solenoid valve reduces, holds or increases caliper/wheel cylinder fluid pressure for front and rear brakes as determined by EBCM signal.

WHEEL SPEED SENSOR

Wheel speed sensors are of a variable reluctance type. Each sensor is mounted in close proximity to a toothed ring. As teeth pass by sensor head, an AC voltage is produced. Sensor signal frequency increases as ring rotation speed increases. See COMPONENT LOCATIONS .

VEHICLE SPEED SENSOR (HOMBRE)

Vehicle Speed Sensor (VSS) performs same function as rear wheel speed sensors. VSS is located on left side of transmission and measures output shaft speed.

COMPONENT LOCATIONS (HOMBRE)

COMPONENT LOCATIONS (HOMBRE)

COMPONENT LOCATIONS (PASSPORT, RODEO & SLX)

COMPONENT LOCATIONS (PASSPORT, RODEO & SLX)

COMPONENT LOCATIONS (TROOPER)

COMPONENT LOCATIONS (TROOPER)

BLEEDING BRAKE SYSTEM

HOMBRE

Note. A two person procedure is required for bleeding brake system. DO NOT perform gravity, pressure or vacuum bleeding procedures.

Two Person Procedure

1. Bleed wheel cylinders and calipers in order specified. See «BRAKE BLEEDING SEQUENCE»(/acura/slx/i-1995-1999/remont/anti-locktraction-control/#anti-lock-brake-system-introduction__brake-bleeding-sequence) . Attach clear bleed hose to bleeder valve on wheel cylinder or caliper. Place other end of bleed hose in container partially filled with brake fluid.
2. Open bleeder valve. Have an assistant slowly depress brake pedal. Close bleeder valve and release brake pedal. Wait 10-15 seconds. Repeat this procedure until pedal feels firm and no air bubbles are detected. Repeat procedure for each wheel cylinder and caliper.

Manual Bleeding (Hydraulic Modulators)

1. Using scan tool, perform motor re-home function. If current Diagnostic Trouble Codes (DTCs) are present, vehicle must be repaired and DTCs cleared before re-home function can be performed. Check fluid level in master cylinder reservoir and fill with DOT 3 brake fluid as required.
2. Attach clear bleed hose to rearward bleeder valve on hydraulic modulator. Place other end of bleed hose in container partially filled with brake fluid. Open bleed valve 1/2-3/4 turn. Slowly depress brake pedal until fluid begins to flow. Close bleed valve and release brake pedal.
3. Repeat procedure until fluid flows with no air bubbles present. Check fluid level in master cylinder frequently and refill as required. Repeat this procedure for forward hydraulic modulator bleed valve.

Manual Bleeding (Wheel Cylinders & Calipers)

1. Bleed wheel cylinders and calipers in order specified. See «BRAKE BLEEDING SEQUENCE»(/acura/slx/i-1995-1999/remont/anti-locktraction-control/#anti-lock-brake-system-introduction__brake-bleeding-sequence) . Attach clear bleed hose to bleeder valve on wheel cylinder or caliper. Place other end of bleed hose in container partially filled with brake fluid.
2. Open bleeder valve. Have an assistant slowly depress brake pedal. Close bleeder valve and release brake pedal. Wait 5 seconds. Repeat this procedure until pedal feels firm and no air bubbles are detected. Repeat procedure for each wheel cylinder and caliper.

TROOPER

Manual Bleeding

1. Clean master cylinder cap and surrounding area, then remove cap. Fill master cylinder. Start engine and allow it to idle.
2. Install clear bleed hose onto first bleed screw to be serviced. See «BRAKE BLEEDING SEQUENCE»(/acura/slx/i-1995-1999/remont/anti-locktraction-control/#anti-lock-brake-system-introduction__brake-bleeding-sequence) . Place other end of bleed hose in container partially filled with brake fluid. Pump brake pedal 3 times and hold depressed. Open bleed screw until brake fluid flows through hose. CAUTION: DO NOT release brake pedal until bleed screw has been tightened.
3. Close bleed screw, and release pedal slowly. Repeat procedure until flow of brake fluid is clear and no air bubbles are detected. Repeat procedure for each wheel. Install ABS main fuse when finished.

Note. Check fluid level in master cylinder frequently during bleeding sequence.

Pressure Bleeding

1. Clean master cylinder cap and surrounding area, then remove cap. With pressure tank at least 1/2 full, connect pressure tank to master cylinder using proper adapter(s). Start engine and allow it to idle.
2. Attach clear bleed hose to first bleed screw to be serviced. See «BRAKE BLEEDING SEQUENCE»(/acura/slx/i-1995-1999/remont/anti-locktraction-control/#anti-lock-brake-system-introduction__brake-bleeding-sequence) . Place other end of hose in clean, transparent container. Partially fill container with clean brake fluid until end of hose is submerged in fluid.
3. Open release valve on pressure tank. Open bleed screw, noting fluid flow. When fluid flowing into container is clear and free of bubbles, close bleed screw securely.
4. Continue bleeding system in the same manner, using appropriate sequence. Close release valve, and remove pressure tank from master cylinder. Install ABS main fuse. Check master cylinder reservoir fluid level.

BRAKE BLEEDING SEQUENCE

BRAKE BLEEDING SEQUENCE

TROUBLE SHOOTING

Note. To verify ABS operation (normal or faulty), perform ABS self-check. See ANTI-LOCK SYSTEM SELF-CHECK under DIAGNOSIS & TESTING.

The Anti-Lock Brake System (ABS) is capable of storing Diagnostic Trouble Codes (DTCs) when a system malfunction is detected. During a malfunction, ABS warning light may flash or remain illuminated. On Passport, Rodeo and Trooper, DTCs can be retrieved by observing ABS warning light, or by using scan tool. On Hombre, a scan tool must be used to retrieve DTCs. See SELF-DIAGNOSTICS. If a DTC is not present, but a malfunction is evident, trouble shooting may be performed by symptom. See SYMPTOM DIAGNOSIS .

SYMPTOM DIAGNOSIS

Symptom diagnosis covers malfunctions not diagnosed using ABS warning light, and which are not detected by EBCM self-diagnostic function. To diagnose by symptom, identify symptom and proceed to specified circuit test under CIRCUIT TESTS . See appropriate SYMPTOM DIAGNOSIS table.

Note. Before proceeding with any circuit tests, perform DIAGNOSTIC SYSTEM CHECK for Hombre, or DIAGNOSTIC CIRCUIT CHECK for Passport and Rodeo. See appropriate 4-WHEEL ANTI-LOCK - SELF-DIAGNOSTICS article. On Trooper, proceed directly to CIRCUIT TESTS.

SYMPTOM DIAGNOSIS (HOMBRE)

SYMPTOM DIAGNOSIS (PASSPORT, RODEO & SLX)

SYMPTOM DIAGNOSIS (TROOPER)

ANTI-LOCK SYSTEM SELF-CHECK

Note. BRAKE warning light should remain on if parking brake is applied and ignition is on.

1. Turn ignition on. ABS warning light and BRAKE warning light should illuminate. Once engine is started, they should go out in a few seconds. If one or both lights stay on, it could indicate a problem associated with system. If both lights turn off, go to next step.
2. Test drive vehicle. ABS system will self-test hydraulic portion of system when vehicle begins to move faster than 8 MPH. A noise coming from the BPMV may be heard during this test. If a problem is detected, a DTC should be set by EBCM.

Passport, Rodeo & SLX

1. Turn ignition on. EBCM will automatically perform self-diagnostics as part of initialization procedure. Initialization procedure will verify motor, modulator, solenoid, relay and indicator operation as well as check wheel speed sensor circuits for shorts to ground/power or opens.
2. If EBCM detects a malfunction in itself or any other system component, a DTC will be set and ABS warning light will remain illuminated. If no malfunction is detected, ABS warning light should turn off about 3 seconds after engine start.
3. About one second after engine start, EBCM will test hydraulic unit. During this test, it is normal to hear a slight mechanical noise from hydraulic unit. If driver's foot is on brake pedal during engine start, initialization will not occur until foot is removed, or until vehicle begins moving faster than 3 MPH.
4. If a malfunction is detected, a DTC will be set and ABS warning light will remain illuminated. If no malfunction is detected, ABS warning light should turn off.

1. Turn ignition on. Note operation of ABS warning light on instrument panel. ABS warning light should illuminate for 3 seconds and then turn off.
2. If ABS warning light does not operate as specified, check for a system malfunction. System malfunction(s) can be detected by different ABS warning light illumination patterns when ignition switch is turned to ON position.
3. ABS warning light may illuminate immediately after power is supplied to EBCM, about 15 seconds after engine start, or when a specified vehicle speed has been reached. Type of malfunction can be narrowed down by knowing timing of light illumination. (Scheme 1)
4. If ABS warning light indicates that a DTC has been set, retrieve DTCs. See RETRIEVING DTCS USING SCAN TOOL or RETRIEVING DTCS USING ABS WARNING LIGHT under SELF-DIAGNOSTICS.
5. ABS warning light will turn off when ignition switch is turned off. If fault is still not repaired, ABS warning light illuminates again with same pattern when ignition switch is turned to ON position.

Scheme 1

SELF-DIAGNOSTICS

Note. Some diagnostic procedures may require use of a Tech 1 or other OBD-II compatible scan tool. Limited information is available on scan tool operating procedures. See scan tool manufacturer's instructions.

RETRIEVING DTCS USING SCAN TOOL

1. Connect scan tool to Data Link Connector (DLC). See «COMPONENT LOCATIONS»(/acura/slx/i-1995-1999/remont/anti-locktraction-control/#anti-lock-brake-system-introduction) . Following scan tool manufacturer's instructions, select appropriate mode to view DTCs. Once DTCs are retrieved, proceed to appropriate DTC IDENTIFICATION table.
2. Identify DTC and perform diagnostic test specified. See appropriate 4-WHEEL ANTI-LOCK - SELF-DIAGNOSTICS article. After repairs, DTCs must be cleared. See CLEARING DIAGNOSTIC TROUBLE CODES.

RETRIEVING DTCS USING ABS WARNING LIGHT

Note. On Hombre, DTCs may only be retrieved or erased with scan tool. See RETRIEVING DTCS USING SCAN TOOL.

Passport, Rodeo, SLX & Trooper

1. When ABS warning light remains on, EBCM will store DTCs and disable ABS system. If DTCs are not displayed, wiring harness from EBCM to ABS warning light may be disconnected. Check and repair harness if necessary.
2. Ensure ignition is off and brake pedal is released. Using a jumper wire, jumper Data Link Connector (DLC) terminals No. 4 and 12. (Scheme 2) Turn ignition on. DTC will be displayed by flashing ABS warning light.
3. A stored DTC will be displayed 3 times, each being separated by a 3.2 second pause. If multiple DTCs are set, second DTC will follow after first DTC is displayed a third time. All DTCs contain 2 digits. First digit of DTC is identified by a series of 0.4 second flashes. After a 1.2 second pause, second digit of DTC will follow in another series of 0.4 second flashes. If no DTCs have been stored, ABS warning light will repeat DTC 12 (system normal).
4. Once DTCs are retrieved, proceed to appropriate DTC IDENTIFICATION table. Identify DTC and perform diagnostic test specified. See appropriate 4-WHEEL ANTI-LOCK - SELF-DIAGNOSTICS article. After repairs, DTCs must be cleared. See CLEARING DIAGNOSTIC TROUBLE CODES.

Scheme 2

Note. Before proceeding with any diagnostic tests, perform DIAGNOSTIC SYSTEM CHECK (Hombre), or DIAGNOSTIC CIRCUIT CHECK (Passport and Rodeo). See appropriate 4-WHEEL ANTI-LOCK - SELF-DIAGNOSTICS article. On Trooper, proceed directly to DIAGNOSTIC TESTS in appropriate 4-WHEEL ANTI-LOCK - SELF-DIAGNOSTICS article.

DTC IDENTIFICATION (HOMBRE)

DTC IDENTIFICATION (PASSPORT, RODEO & SLX)

DTC IDENTIFICATION (TROOPER)

DTCs are cleared from EBCM memory by using a scan tool. EBCM will not allow clearing of DTCs until all DTCs have been displayed. DTCs cannot be cleared by unplugging EBCM, disconnecting battery or turning ignition off. Follow scan tool manufacturer's instructions when clearing DTCs.

Three methods may be used to clear DTCs from EBCM memory

1. Scan Tool Method To clear DTCs using scan tool, follow scan tool manufacturer's instructions.
2. Flash Code Method Enable flash codes by jumping DLC terminals. See RETRIEVING DTCS USING ABS WARNING LIGHT. Depress brake pedal 6 or more times within 3 seconds. Current and history DTCs will be cleared from EBCM memory.
3. Ignition Cycle Default Method One ignition cycle equals ignition on, and vehicle driven faster than 10 MPH. If no DTCs occur for 100 ignition cycles, any existing DTCs are cleared from EBCM memory. Manufacturer does not recommend this method for clearing DTCs.

EBCM will not allow clearing of DTCs until all DTCs have been displayed. DTCs cannot be cleared by unplugging EBCM, disconnecting battery or turning ignition off.

Without Scan Tool

1. With the ignition off jumper pins 4 &12 of the DLC connector.
2. Switch the ignition on & allow the ABS lamp to flash at least once before proceeding.
3. Depress the brake pedal by hand until you hear the solenoid click, then release the pedal. Repeat 8 times within 3 seconds.

After the 8th pedal cycle the ABS lamp stops flashing, lights for 1 second, then begins flashing code 12 (no codes). Memory is erased once code 12 flashes 4 times.

Two methods may be used to clear DTCs from EBCM memory

1. With Scan Tool Connect scan tool to DLC. Follow scan tool manufacturer's instructions to clear DTCs.
2. Without Scan Tool Ensure ignition is off and brake pedal is not depressed. Using a jumper wire, jumper DLC terminals No. 4 and 12 together, and within 3 seconds, depress and release brake pedal 6 or more times. (Scheme 2) DTCs will not be cleared if brake pedal is not depressed within 3 seconds of jumping DLC terminals.

TEST A-1: ABS WARNING LIGHT OFF, NO DTCS STORED

1. Turn ignition off. Disconnect EBCM harness connector (10-pin). Using a fused jumper wire, jumper EBCM harness connector terminal "B" (Green wire) to ground. Turn ignition on. If ABS warning light illuminates, go to next step. If ABS warning light does not illuminate, go to step 3).
2. Inspect EBCM harness connector for damage or corrosion. Repair as necessary. If harness connector is okay, replace EBCM.
3. Inspect GAUGE fuse (10-amp), located in interior fuse block. If fuse is blown, go to next step. If fuse is okay, go to step 5).
4. Turn ignition off. Replace GAUGE fuse (10-amp). Turn ignition on. Remove GAUGE fuse and inspect. If fuse is blown, repair Pink wire between GAUGE fuse and instrument cluster for a short to ground. If fuse is okay, check Pink wire for an intermittent problem.
5. Remove ABS warning light bulb and inspect. Replace if necessary. If bulb is okay, repair open in Pink wire between GAUGE fuse and ABS warning light, or Green wire between ABS warning light and EBCM.

TEST A-2: ABS (AMBER) WARNING LIGHT ON CONSTANTLY, NO DTCS STORED

1. Connect scan tool to DLC. Using scan tool, select LAMP TEST. Attempt to flash ABS warning light. If ABS warning light flashes, malfunction is not present at this time. If ABS warning light does not flash, go to next step.
2. Turn ignition off. Disconnect EBCM harness connector. Turn ignition on. Using a fused jumper wire, connect terminal No. 6 (Violet wire) at EBCM harness connector to ground. If ABS warning light remains illuminated, go to next step. If ABS warning light turns off, check Violet wire for poor connection. If no problem is found, replace EBCM.
3. Turn ignition off. Remove ABS fuse (10-amp), located in interior fuse box. Turn ignition on. Using DVOM, measure voltage between ground and terminal No. 6 (Violet wire) at EBCM harness connector. If voltage is one volt or less, go to next step. If voltage is not as specified, repair Violet wire for a short to power.
4. Turn ignition off. Reinstall ABS fuse. Disconnect lamp driver relay from harness, located in relay box next to EBCM. Turn ignition on. If ABS warning light is off, go to next step. If ABS warning light is on, repair Violet wire between lamp driver relay and instrument cluster for a short to ground.
5. Turn ignition off. Using DVOM, resistance of Violet wire between terminal No. 4 of lamp driver relay and terminal No. 6 of EBCM. If resistance is greater than 2 ohms, go to next step. If resistance is 2 ohms or less, reconnect all harness connections. Turn ignition on. If ABS warning light illuminates, replace EBCM.
6. Check for an open in Violet wire between terminal No. 4 of lamp driver relay and terminal No. 6 of EBCM. Repair as necessary. If Violet wire is okay, replace lamp driver relay.

TEST A-3: ABS WORKS FREQUENTLY, BUT VEHICLE DOES NOT DECELERATE

1. Turn ignition off. Disconnect "G" sensor and EBCM harness connectors. Using DVOM, check for continuity between EBCM terminals No. 28 and 41. If continuity is present, go to next step. If continuity is not present, replace EBCM.
2. Reconnect EBCM harness connector. Turn ignition on. Measure voltage between "G" sensor harness connector terminals No. 1 (Yellow/Red wire) and No. 2 (Yellow/Black wire). If voltage is 5 volts, go to next step. If voltage is not as specified, go to step 4).
3. Turn ignition off. Measure resistance between "G" sensor harness connector terminals No. 2 (Yellow/Black wire) and No. 3 (Yellow/Green wire). If resistance is 51 k/ohms or less, go to step 6). If resistance is not as specified, go to step 7).
4. Check for continuity in Yellow/Red wire between "G" sensor and EBCM. If continuity is present, go to next step. If continuity is not present, repair open in Yellow/Red wire.
5. Check for continuity in Yellow/Black wire between "G" sensor and EBCM. If continuity is present, replace EBCM. If continuity is not present, repair open in Yellow/Black wire.
6. Check "G" sensor. See TEST C-1: "G" SENSOR INSPECTION under COMPONENT TESTS. Repair as necessary. If "G" sensor tests okay, go to step 8).
7. Check for continuity in Yellow/Green wire between "G" sensor and EBCM. If continuity is present, replace EBCM. If continuity is not present, repair open in Yellow/Green wire.
8. Check each wheel speed sensor for looseness or powdered iron sticking to components. Check axle components for proper installation. Test drive vehicle and check for equal braking force distribution between front and rear of vehicle. Repair as necessary. If no problem is found, go to next step.
9. Check output of each wheel speed sensor. See TEST C-2: SENSOR OUTPUT INSPECTION under COMPONENT TESTS. Repair as necessary. If wheel speed sensors and harnesses are okay, go to next step.
10. Check transmission switch input. See TEST C-4: TRANSMISSION INPUT INSPECTION under COMPONENT TESTS. Repair as necessary. If transmission switch input is okay, go to next step.
11. Check front axle switch input. See TEST C-3: FRONT AXLE SWITCH INSPECTION under COMPONENT TESTS. Repair as necessary. If transmission switch input is okay, replace EBCM.

TEST A-4: UNEVEN BRAKING OCCURS WHILE ABS IS OPERATING

1. Check each wheel speed sensor for looseness, or powdered iron sticking to wheel sensor or sensor ring. Repair as necessary. If no problem is found, go to next step.
2. Check output of each wheel speed sensor. See TEST C-2: SENSOR OUTPUT INSPECTION under COMPONENT TESTS. Repair as necessary. If wheel speed sensors and harnesses are okay, go to next step.
3. Ensure all hydraulic brakelines are connected properly (in correct location and order). Repair as necessary. If no problem is found, replace EBCM.

TEST A-5: WHEELS LOCK DURING BRAKING

1. If ABS system does not operate, go to step 3). If ABS system operates, check for normal transmission input. See TEST C-4: TRANSMISSION INPUT INSPECTION under COMPONENT TESTS. If transmission input is okay, go to next step. If transmission input is not okay, repair or replace transmission switch and/or wiring as necessary.
2. Check front axle switch for normal operation. See TEST C-3: FRONT AXLE SWITCH INSPECTION under COMPONENT TESTS. Repair or replace front axle switch and/or wiring as necessary. If front axle switch is okay, ensure hydraulic unit is properly grounded. If ground is okay, replace hydraulic unit.
3. Ensure wheel speed sensor output is normal. See TEST C-2: SENSOR OUTPUT INSPECTION under COMPONENT TESTS. If wheel speed sensor output is okay, go to next step. If wheel speed sensor output is not okay, repair or replace sensor and/or wiring as necessary.
4. Ensure transmission switch input is normal. See TEST C-4: TRANSMISSION INPUT INSPECTION under COMPONENT TESTS. If transmission switch input is okay, go to step 2). If transmission switch input is not okay, repair or replace transmission switch and/or wiring as necessary.

TEST A-6: BRAKE PEDAL FEEL IS ABNORMAL

1. Depress brake pedal. If brakelights illuminate, go to next step. If brakelights do not illuminate, go to step 3).
2. Turn ignition off. Disconnect EBCM harness connector. Using DVOM, measure voltage between EBCM harness connector terminals No. 28 (Black wire) and No. 48 (Green/Yellow wire). If reading is battery voltage, go to step 4). If reading is not as specified, go to next step.
3. Remove and inspect STOP fuse (15-amp), located in interior fuse block. If fuse is okay, go to next step. If fuse is blown, check for a short circuit and replace fuse.
4. Check for continuity between ground and EBCM harness connector terminals No. 28, 29 and 39 (Black wires). If continuity is present, go to step 6). If continuity is not present, repair body ground harness.
5. Check brakelight switch. Repair as necessary. If brakelight switch is okay, repair brakelight switch harness.
6. Check all harness connectors for damage or corrosion. Repair as necessary. If no problem is found, check for hydraulic system leakage. Repair as necessary. See DISC & DRUM article.

TEST A-7: BRAKING SOUND FROM HYDRAULIC UNIT (BRAKES RELEASED)

Note. A sound may be heard from hydraulic unit the first time vehicle begins to move forward after engine start, or when moving slower than 6 MPH. Sound is caused by ABS self-check and is normal operation. Also, ABS may operate without depressing brake pedal under certain conditions such as: clutch operation, high-speed turns, poor road conditions, when entering a driveway, or during excessive engine RPM (greater than 5000 RPM).

1. If sound is heard after vehicle starts to move and is not the first engine start, or when vehicle speed is greater than 6 MPH, go to next step.
2. Check wheel speed sensor and toothed ring condition. Check for looseness or powdered iron sticking to components. Repair as necessary. If no problem is found, go to next step.
3. Check each wheel speed sensor output. See TEST C-2: SENSOR OUTPUT INSPECTION under COMPONENT TESTS. Repair as necessary. If wheel speed sensors and harnesses are okay, replace EBCM.

TEST B-1: ABS WARNING LIGHT ON, NO DTCS STORED

Turn ignition off. Disconnect EBCM harness connector (10-pin). Turn ignition on. If ABS warning light illuminates and remains on, repair Green wire between ABS warning light and EBCM for a short to ground. If ABS warning light does not remain on, replace EBCM.

TEST B-2: ABS (AMBER) WARNING LIGHT ON INTERMITTENTLY, NO DTCS STORED

1. Turn ignition off. Disconnect EBCM harness connector. Connect a test light between ground and terminal No. 13 (Red/Yellow wire) at EBCM harness connector. Observe test light while moving wiring harness and connections. If test light remains on steady, go to next step. If test light does not remain on steady, repair poor connection in Red/Yellow wire.
2. Connect test light between ground and terminal No. 4 (Yellow wire) at EBCM harness connector. Turn ignition on. Observe test light while moving wiring harness and connections. If test light remains on steady, go to next step. If test light does not remain on steady, repair poor connection in Yellow wire.
3. Problem is not present at this time. Check for incorrect wiring harness routing or loose ground connections. Repair as necessary. If no problem is found, go to TEST A-2: ABS (AMBER) WARNING LIGHT ON CONSTANTLY, NO DTCS STORED.

TEST B-3: ABS WARNING LIGHT DOES NOT ILLUMINATE WITH KEY ON/ENGINE OFF

1. Ensure GAUGE fuse (10-amp) is okay. Fuse is located in interior fuse block. Ensure ABS warning light bulb is not burned out. Replace if necessary. Go to next step.
2. Turn ignition off. Disconnect EBCM harness connector. Turn ignition on. Using DVOM, measure voltage between EBCM harness connector terminals No. 28 (Black wire) and No. 30 (Yellow wire). If battery voltage is present, go to next step. If battery voltage is not present, repair wiring or connections as necessary.
3. Turn ignition off. Check for continuity between ground and EBCM harness connector terminals No. 28, 29 and 39 (Black wires). If continuity is not present, repair appropriate wiring or connections as necessary. If continuity is present, check for loose harness connectors and repair as necessary. If harness connectors are okay, replace EBCM.

TEST C-1: ABS (AMBER) WARNING LIGHT OFF CONSTANTLY, NO DTCS STORED

1. Connect scan tool to DLC. Turn ignition on. Using scan tool, select LAMP TEST. Attempt to command ABS warning light on. If ABS warning lamp illuminates, malfunction is not present at this time. If ABS warning light does not illuminate, go to next step.
2. Turn ignition off. Disconnect lamp driver relay from harness, located in relay box next to EBCM. Turn ignition on. Using a fused jumper wire, connect terminal No. 5 (Violet/White wire) at lamp driver relay harness connector to ground. If ABS warning light illuminates, go to step 7). If ABS warning light does not illuminate, go to next step.
3. Turn ignition off. Disconnect instrument cluster harness connector. Using DVOM, measure resistance of Violet/White wire between terminal No. 5 of lamp driver relay harness connector and terminal No. 2 of instrument cluster harness connector. If resistance is 2 ohms or less, go to next step. If resistance is not as specified, repair open or poor connection in Violet/White wire.
4. Inspect ABS warning light bulb. Replace bulb if faulty. If bulb is okay, go to next step.
5. Turn ignition on. Connect test light between ground and terminal No. 5 (Violet/White wire) at lamp driver relay harness connector. If test light illuminates, repair Violet/White wire for a short to power. If test light does not illuminate, go to next step.
6. Turn ignition off. Reconnect lamp driver relay, instrument cluster and EBCM harness connectors. Turn ignition on. If ABS warning light illuminates for 3 seconds, and then turns off, problem is intermittent. If ABS warning light operation is not as specified, replace EBCM.
7. Turn ignition off. Using DVOM, measure voltage between ground and terminal No 2 (Yellow wire) at lamp driver relay harness connector. If voltage is 10 volts or greater, go to next step. If voltage is not as specified, repair open or poor connection in Yellow wire.
8. Check Violet wire between terminal No. 4 of lamp driver relay harness connector and terminal No. 6 of EBCM harness connector. Repair as necessary. If wire is okay, replace lamp driver relay.

TEST D-1: ABS ACTIVE INDICATOR LIGHT MALFUNCTIONING

1. Turn ignition on. If ABS ACTIVE indicator light is illuminated constantly, go to step 6). If ABS ACTIVE indicator light is not illuminated constantly, go to next step.
2. Check ABS and BRAKE warning lights. If operation is okay, go to next step. If operation is not okay, check instrument cluster warning light circuits. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT section. Repair as necessary.
3. Turn ignition off. Check connections of White/Green wire at terminal No. 5 of instrument cluster and terminal No. 7 of EBCM. Repair as necessary. If connections are okay, inspect ABS ACTIVE light bulb. Replace if necessary. If bulb is okay, go to next step.
4. Disconnect EBCM harness connector. Using DVOM, measure resistance of White/Green wire between terminal No. 5 of instrument cluster harness connector and terminal No. 7 of EBCM. If resistance is 2 ohms or less, go to next step. If resistance is not as specified, repair open or high resistance in White/Green wire.
5. Remove and inspect instrument cluster. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT section. Repair as necessary. If no problem is found, replace EBCM.
6. Turn ignition off. Disconnect EBCM harness connector. Turn ignition on. If ABS ACTIVE indicator light illuminates, go to next step. If ABS ACTIVE indicator light does not illuminate, replace EBCM.
7. Check White/Green wire between terminal No. 5 of instrument cluster and terminal No. 7 of EBCM for a short to ground. Repair as necessary. If wire is okay, remove and inspect instrument cluster. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT section. Repair as necessary.

COMPONENT TESTS

Note. The following component tests apply to Trooper only. On Hombre, Passport and Rodeo, component testing is combined in diagnostic tests. See appropriate 4-WHEEL ANTI-LOCK - SELF-DIAGNOSTICS article.

TEST C-1: "G" SENSOR INSPECTION

Remove "G" sensor mounting bolt (leave harness connector connected). Turn ignition on. Using DVOM, measure voltage (backprobe) between "G" sensor harness connector terminals No. 2 (Yellow/Black wire) and No. 3 (Yellow/Green wire). Move "G" sensor forward and backward. If voltage varies between zero and 5 volts, check for an intermittent problem. If voltage is not as specified, replace "G" sensor.

TEST C-2: SENSOR OUTPUT INSPECTION

1. Turn ignition off. Disconnect EBCM harness connector. Raise and support vehicle. Using DVOM set to AC scale, measure AC voltage between EBCM harness connector terminals No. 10 (White wire) and No. 35 (Red wire) while turning left front wheel by hand at least one Revolution Per Second (RPS). If voltage is less than 200 millivolts, go to next step. If voltage is 200 millivolts or greater, sensor output is okay.
2. Measure AC voltage between EBCM harness connector terminals No. 14 (Blue wire) and No. 15 (Green wire) while turning right front wheel by hand at least one RPS. If voltage is less than 200 millivolts, go to next step. If voltage is 200 millivolts or greater, sensor output is okay.
3. Measure AC voltage between EBCM harness connector terminals No. 12 (White/Blue wire) and No. 40 (Orange/Blue wire) while turning left rear wheel by hand at least one RPS. If voltage is less than 200 millivolts, go to next step. If voltage is 200 millivolts or greater, sensor output is okay.
4. Measure AC voltage between EBCM harness connector terminals No. 11 (Orange wire) and No. 38 (White wire) while turning right rear wheel by hand at least one RPS. If voltage is less than 200 millivolts, go to next step. If voltage is 200 millivolts or greater, sensor output is okay.
5. Disconnect wheel speed sensor harness connectors. Using DVOM, measure resistance of each wheel speed sensor. If resistance is 1.3-1.9 k/ohms, connector or harness between wheel speed sensor and EBCM is faulty. Repair as necessary. If resistance is not as specified, replace appropriate wheel speed sensor.

TEST C-3: FRONT AXLE SWITCH INSPECTION

1. Turn ignition off. Disconnect EBCM harness connector. Turn ignition on. Place transfer case gear selector in 2H position. Using DVOM, measure voltage between EBCM harness connector terminals No. 28 (Black wire) and No. 44 (Light Green wire). If battery voltage is present, leave DVOM connected and go to next step. If battery voltage is not present, go to step 4).
2. Place transfer case gear selector in 4H position. If zero volts is present, leave DVOM connected and go to next step. If voltage is not as specified, go to step 4).
3. Place transfer case gear selector in 4L position. If zero volts is present, front axle switch is okay. If voltage is not as specified, go to next step.
4. Turn ignition off. Disconnect front axle switch harness connector. Place transfer case gear selector in 2H position. Using DVOM, check for continuity between front axle switch terminals. If continuity is present, replace front axle switch. If continuity is not present, leave DVOM connected and go to next step.
5. Check for continuity between front axle switch terminals with transfer case gear selector in 4L and 4H positions. If continuity is present, repair faulty front axle switch connector or harness. If continuity is not present, replace front axle switch.

Automatic Transmission

1. Turn ignition off. Place gear selector lever in "P" position. Disconnect EBCM harness connector. Using DVOM, check for continuity between EBCM harness connector terminals No. 22 (Purple/White wire) and No. 28 (Black wire). If continuity is present, repair Purple/White wire for a short to ground. If continuity is not present, go to next step.
2. Turn ignition on. Measure voltage between EBCM harness connector terminals No. 22 (Purple/White wire) and No. 28 (Black wire). If voltage is less than 6 volts with gear selector lever in "L" and "R" positions, leave DVOM connected and go to next step. If voltage is not as specified, check for faulty harness between transmission switch and EBCM. Repair as necessary. If no problem is found, replace transmission switch.
3. If voltage is 6.6-9.0 volts with gear selector lever in 2nd, 3rd, 4th and "N" positions, transmission switch is okay. If voltage is not as specified, check for faulty harness between transmission switch and EBCM. Repair as necessary. If no problem is found, replace transmission switch.

Manual Transmission

1. Turn ignition off. Place gear selector lever in "N" position. Disconnect EBCM harness connector. Using DVOM, check for continuity between EBCM harness connector terminals No. 22 (Purple/White wire) and No. 28 (Black wire). If continuity is present, repair Purple/White wire for a short to ground. If continuity is not present, go to next step.
2. Turn ignition on. Measure voltage between EBCM harness connector terminals No. 22 (Purple/White wire) and No. 28 (Black wire). If voltage is greater than 9.6 volts with gear selector lever in 1st, 2nd and "R" positions, leave DVOM connected and go to next step. If voltage is not as specified, check for faulty harness between transmission switch and EBCM. Repair as necessary. If no problem is found, replace transmission switch.
3. If voltage is 6.6-9.0 volts with gear selector lever in 3rd, 4th, 5th and "N" positions, transmission switch is okay. If voltage is not as specified, check for faulty harness between transmission switch and EBCM. Repair as necessary. If no problem is found, replace transmission switch.

TEST C-5: MOTOR RELAY INSPECTION

1. Remove motor relay. Using fused jumper wires, apply battery voltage and ground to motor relay terminals No. 2 and 3. (Scheme 3) Using DVOM, ensure continuity is present between motor relay te rminals No. 1 and 4.
2. Remove jumper wires. Ensure continuity is not present between motor relay terminals No. 1 and 4. Replace motor relay if continuity is not as specified.

TEST C-6: VALVE RELAY INSPECTION

1. Remove valve relay. Using fused jumper wires, apply battery voltage and ground to valve relay terminals No. 2 and 3. (Scheme 4) Using DVOM, ensure continuity is present between motor relay te rminals No. 1 and 5. Continuity should not be present between valve relay terminals No. 1 and 4.
2. Remove jumper wires. Ensure continuity is not present between valve relay terminals No. 1 and 5. Continuity should now be present between valve relay terminals No. 1 and 4. Replace valve relay if continuity is not as specified.

Scheme 3

Scheme 4

REMOVAL & INSTALLATION

Note. Some removal and installation procedures may require the use of a scan tool. Limited information is available on scan tool operating procedures. See scan tool manufacturer's instructions.

Removal & Installation (Hombre)

1. Disconnect negative battery cable. Disconnect EBCM harness connectors. Disconnect harness connector from combination valve. Disconnect front and rear brakelines. Remove 3 hydraulic lines from tube adapters on BPMV. Remove bolts securing BPMV bracket to vehicle mounting bracket. Remove BPMV from vehicle.
2. Remove 4 EBCM mounting bolts and remove EBCM from BPMV. (Scheme 5) To install, reverse removal procedure using a NEW EBCM gasket. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/acura/slx/i-1995-1999/remont/anti-locktraction-control/#anti-lock-brake-system-introduction).

Removal & Installation (Passport, Rodeo & SLX)

Disconnect negative battery cable. Remove EBCM harness connector mounting screw and disconnect EBCM harness connector. Remove EBCM mounting nuts. (Scheme 6) Remove EBCM. To install, reverse removal procedure. Tighten nuts to specification. See TORQUE SPECIFICATIONS.

Removal & Installation (Trooper Dash Mounted)

Disconnect negative battery cable. Remove front console and lower cluster assemblies. Disconnect EBCM harness connector. Remove 4 EBCM mounting bolts. Remove EBCM from bracket. (Scheme 7) To install, reverse removal procedure.

Removal & Installation (Trooper Seat Mounted)

Disconnect negative battery cable. Remove appropriate front seat. Remove EBCM mounting bolts. Disconnect EBCM harness connector. Remove EBCM. To install, reverse removal procedure.

Scheme 5

Scheme 6

Scheme 7

1. Raise and support vehicle. Remove front wheel. Remove brake caliper, hub and rotor. Disconnect wheel speed sensor harness connector. Remove harness clips from front side of upper control arm. Remove wheel speed sensor mounting bolts and splash shield mounting bolts. (Scheme 8)
2. Remove wheel speed sensor and splash shield assembly. Remove splash shield gasket. To install, reverse removal procedure. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/acura/slx/i-1995-1999/remont/anti-locktraction-control/#anti-lock-brake-system-introduction).

Removal & Installation (Passport, Rodeo, SLX & Trooper)

1. Raise and support vehicle. Remove front wheel. Disconnect wheel speed sensor harness connector. Remove upper and lower wheel speed sensor harness mounting bolts. (Scheme 9)
2. Remove wheel speed sensor mounting bolt. Remove wheel speed sensor. To install, reverse removal procedure. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/acura/slx/i-1995-1999/remont/anti-locktraction-control/#anti-lock-brake-system-introduction).

Scheme 8

Scheme 9

1. Remove center console. Remove "G" sensor/accelerometer harness connector. Remove "G" sensor/accelerometer mounting bolt. Remove "G" sensor/accelerometer. (Scheme 10)or (Scheme 11).
2. To install, reverse removal procedure. Ensure "G" sensor/accelerometer is installed facing in the correct direction. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/acura/slx/i-1995-1999/remont/anti-locktraction-control/#anti-lock-brake-system-introduction).

Scheme 10

Scheme 11

1. Disconnect negative battery cable. Disconnect EBCM harness connectors. Disconnect combination valve harness connector. (Scheme 5) Disconnect front and rear brakelines. Seal brakeline ends using tape or other suitable material to prevent foreign matter from entering brakelines.
2. Remove hydraulic lines from tube adapters on BPMV. Remove BPMV bracket mounting bolts. Remove BPMV from vehicle. Remove EBCM mounting bolts. Remove EBCM from BPMV. Remove 3 Allen bolts from combination valve. Remove combination valve from BPMV.
3. Remove transfer tubes. Remove bolts retaining BPMV to bracket. To install, reverse removal procedure using NEW EBCM gasket and transfer tubes. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/acura/slx/i-1995-1999/remont/anti-locktraction-control/#anti-lock-brake-system-introduction).

HYDRAULIC UNIT

1. Using Tech 1 scan tool, perform GEAR TENSION RELIEF function (F5). Follow scan tool manufacturer's instructions.
2. Disconnect negative battery cable. Drain brake fluid in reservoir, master cylinder and hydraulic unit. Remove hydraulic unit mounting bolt. (Scheme 12) Disconnect hydraulic unit solenoid harness connectors. Remove hydraulic unit from vehicle. To install, reverse removal procedure. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/acura/slx/i-1995-1999/remont/anti-locktraction-control/#anti-lock-brake-system-introduction).

Removal & Installation (Trooper)

Disconnect battery cables. Remove battery and battery bracket assembly. Disconnect hydraulic unit harness connector. Disconnect brakelines and plug openings. Remove ground wire bolt. Remove bracket bolt and nut. Remove bracket. To install, reverse removal procedure. Tighten bolts to specification. See TORQUE SPECIFICATIONS .

Scheme 12

Removal & Installation (2WD Passport, Rodeo & SLX)

Disconnect rear wheel speed sensor harness connector. Remove rear wheel speed sensor mounting bolt and remove sensor from differential. (Scheme 13) To install, reverse removal procedure. Tighten bolts to specification. See TORQUE SPECIFICATIONS.

Removal & Installation (4WD Passport, Rodeo, SLX & Trooper)

Disconnect rear wheel speed sensor harness connector. Remove clips, sensor cable bolt, sensor retaining bolts and speed sensors from each rear wheel. (Scheme 14) To install, reverse removal procedure. Tighten bolts to specification. See TORQUE SPECIFICATIONS.

Scheme 13

Scheme 14

Disconnect VSS harness connector. Remove clips, sensor cable bolt, sensor retaining bolt and VSS. (Scheme 15) To install, reverse removal procedure. Tighten bolts to specification. See TORQUE SPECIFICATIONS.

Scheme 15

TORQUE SPECIFICATIONS (HOMBRE)

TORQUE SPECIFICATIONS (HOMBRE)

TORQUE SPECIFICATIONS (PASSPORT, RODEO & SLX)

TORQUE SPECIFICATIONS (PASSPORT, RODEO & SLX)

TORQUE SPECIFICATIONS (TROOPER)

TORQUE SPECIFICATIONS (TROOPER)

4-Wheel Anti-Lock Brake System Wiring Diagram (Hombre 2.2L). Scheme 16

4-Wheel Anti-Lock Brake System Wiring Diagram (Hombre 4.3L). Scheme 17

4-Wheel Anti-Lock Brake System Wiring Diagram (Oasis). Scheme 18

4-Wheel Anti-Lock Brake System Wiring Diagram (Rodeo & Honda Passport). Scheme 19

4-Wheel Anti-Lock Brake System Wiring Diagram (Trooper & Acura SLX - 1 Of 2). Scheme 20

4-Wheel Anti-Lock Brake System Wiring Diagram (Trooper & Acura SLX - 2 Of 2). Scheme 21

See also:
• COMPONENT LOCATIONS
• BRAKE BLEEDING SEQUENCE
• ANTI-LOCK SYSTEM SELF-CHECK
• SYMPTOM DIAGNOSIS
• TEST A-1
• TEST B-1
• TEST A-2
• TEST B-2
• TEST C-1
• TEST D-1
• TEST A-3
• TEST A-4
• TEST A-5
• TEST A-6
• TEST A-7
• TEST B-3