DTC 21
DTC 21, 22, 23, 24: ABS Sensor System
CIRCUIT OPERATION
^ A toothed ABS rotor generates a voltage pulse as it moves across the pickup field of each ABS sensor.
^ The amount of voltage generated at each wheel is determined by the clearance between the ABS rotor teeth and the ABS sensor, and by the speed of rotation.
^ The ABS sensors transmit the frequency of the voltage pulses and the amount of voltage generated by each pulse to the ABS-ECU.
^ The hydraulic unit modulates the amount of braking force individually applied to each wheel cylinder.
ABS DTC SET CONDITIONS
^ DTCs 11, 12, 13, 14 are output when signal is not input due to breakage of the wires of one or more of the four ABS sensors.
^ DTCs 21, 22, 23, 24 are output in the following cases:
^ Open circuit is not found but no input is received by one or more of the four ABS sensors at 10 km/h (6 mph) or more.
^ Sensor output drops due to a malfunctioning ABS sensor or warped ABS rotor.
TROUBLESHOOTING HINTS
The most likely causes for these DTCs to set are:
DTC 11, 12, 13, 14
^ Malfunction of the ABS sensor
^ Damaged wiring harness or connector
^ Malfunction of the brake modulator hydraulic unit (integrated with ABS-ECU)
The most likely causes for these DTCs to set are: DTC 21, 22, 23, 24
^ Malfunction of the ABS sensor
^ Damaged wiring harness or connector
^ Malfunction of the brake modulator hydraulic unit (integrated with ABS-ECU)
^ Malfunction of the ABS rotor
^ Malfunction of the wheel bearing
^ Excessive clearance between the ABS sensor and ABS rotor
DIAGNOSIS
Required Special Tools:
^ MB991223: Harness Set
^ MB991529: Diagnostic Trouble Code Check Harness
^ MB991958: Scan Tool (MUT-III Sub Assembly)
^ MB991824: Vehicle Communication Interface (V.C.I.)
^ MB991827: MUT-III USB Cable
^ MB991911: MUT-III Main Harness B
STEP 1. Using scan tool MB991958, check data list.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the LOOK (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 as shown in the illustration.
2. Start the engine.
3. Set scan tool MB991958 to the data reading mode, and check the data list items by driving the vehicle.
^ Item 11 (DTC 11 or 21 is set): Front right ABS sensor
^ Item 12 (DTC 12 or 22 is set): Front left ABS sensor
^ Item 13 (DTC 13 or 23 is set): Rear right ABS sensor
^ Item 14 (DTC 14 or 24 is set): Rear left ABS sensor
4. Turn the ignition switch to the LOCK (OFF) position.
Q: Is the ABS sensor input normal?
YES: This malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope With Intermittent Malfunction.
NO: Go to Step 2.
STEP 2. Check the ABS sensor installation.
Q: Is the ABS sensor bolted securely in place at the front knuckle or the rear knuckle?
YES: Go to Step 3.
NO: Install it properly. Then go to Step 15.
STEP 3. Inspect the ABS sensor and/or ABS rotor.
Check items:
^ ABS sensor internal resistance: 1.24 - 1.64 kOhms
^ Insulation between the ABS sensor body and the connector terminals
^ Toothed ABS rotor check
Q: Is the ABS sensor or ABS rotor damaged?
YES: Replace it. Then go to Step 15.
NO: Go to Step 4.
STEP 4. Check ABS sensor circuit. Measure the resistance at the ABS-ECU connector B-118.
1. Disconnect the connector B-118 and measure at the harness side.
2. Measure the resistance between the ABS-ECU connector terminals.
^ If DTC 11 or 21 is set: between terminals 29 and 30
^ If DTC 12 or 22 is set: between terminals 22 and 31
^ If DTC 13 or 23 is set: between terminals 8 and 9
^ If DTC 14 or 24 is set: between terminals 6 and 7
Standard Value: 1.24 - 1.64 kOhms
Q: Is the resistance within the standard value?
YES: Go to Step 13.
NO
NO
NO
NO
STEP 5. Check the following connectors.
^ ABS-ECU connector B-118
^ Intermediate connector A-29
^ Front ABS sensor (LH) connector A-03
Check the connectors for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are the connectors and terminals in good condition?
YES: Go to Step 6.
NO: Repair it and then go to Step 15.
STEP 6. Check the following harness wires.
^ The wire between ABS-ECU connector B-118 (terminal 22) and front ABS sensor (LH) connector A-03 (terminal 2)
^ The wire between ABS-ECU connector B-118 (terminal 31) and front ABS sensor (LH) connector A-03 (terminal 1)
Q: Is any harness wire damaged?
YES: Repair or replace it and then go to Step 15.
NO: Go to Step 15.
STEP 7. Check the following connectors.
^ ABS-ECU connector B-118
^ Intermediate connectors C-111, C-122
^ Front ABS sensor (RH) connector A-27 Check the connectors for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are the connectors and terminals in good condition?
YES: Go to Step 8.
NO: Repair it and then go to Step 15.
STEP 8. Check the following harness wires.
^ The wire between ABS-ECU connector B-118 (terminal 29) and front ABS sensor (RH) connector A-27 (terminal 1)
^ The wire between ABS-ECU connector B-118 (terminal 30) and front ABS sensor (RH) connector A-27 (terminal 2)
Q: Is any harness wire damaged?
YES: Repair or replace it and then go to Step 15.
NO: Go to Step 15.
STEP 9. Check the following connectors.
^ ABS-ECU connector B-118
^ Intermediate connectors C-113, C-122, D-34
^ Rear ABS sensor (LH) connector D-13
Check the connectors for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are the connectors and terminals in good condition?
YES: Go to Step 10.
NO: Repair it and then go to Step 15.
STEP 10. Check the following harness wires.
^ The wire between ABS-ECU connector B-118 (terminal 6) and rear ABS sensor (LH) connector D-13 (terminal 1)
^ The wire between ABS-ECU connector B-118 (terminal 7) and rear ABS sensor (LH) connector D-13 (terminal 2)
Q: Is any harness wire damaged?
YES: Repair or replace it and then go to Step 15.
NO: Go to Step 15.
STEP 11. Check the following connectors.
^ ABS-ECU connector B-118
^ Intermediate connectors C-113, C-122, D-34
^ Rear ABS sensor (RH) connector D-06 Check the connectors for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are the connectors and terminals in good condition?
YES: Go to Step 12.
NO: Repair it and then go to Step 15.
STEP 12. Check the following harness wires:
^ The wire between ABS-ECU connector B-118 (terminal 8) and rear ABS sensor (RH) connector D-06 (terminal 1)
^ The wire between ABS-ECU connector B-118 (terminal 9) and rear ABS sensor (RH) connector D-06 (terminal 2)
Q: Is any harness wire damaged?
YES: Repair or replace it and then go to Step 15.
NO: Go to Step 15.
STEP 13. Measure the ABS sensor output voltage.
Output Voltage:
^ When measured with a voltmeter: 42 mV or more
^ When measured with an oscilloscope (maximum voltage): 120 mV or more
Q: Does the voltage meet the specification?
YES: Replace the brake modulator hydraulic unit (integrated with ABS-ECU). Then go to Step 15.
NO: Go to Step 14.
STEP 14. Check the wheel bearing.
If play on the wheel bearing is not within the standard value, replace the wheel bearing.
Limit Value: 0.05 mm (0.002 inch)
Q: Is play on the wheel bearing within the standard value?
YES: Go to Step 15.
NO: Replace it and then go to Step 15.
STEP 15. Recheck for diagnostic trouble code.
Check again if the DTC is set.
1. Turn the ignition switch to the ON position.
2. Erase the DTC.
3. Turn the ignition switch to the LOCK (OFF) position.
4. Turn the ignition switch to the ON position.
5. Check if the DTC is set.
6. Turn the ignition switch to the LOCK (OFF) position.
Q: Do the diagnostic trouble codes 11, 12, 13, 14, 21, 22, 23 or 24 reset?
YES: Go to Step 1.
NO: The procedure is complete.