ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS
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ANTI-LOCK BRAKING SYSTEM (ABS)
35B-5
ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS
INTRODUCTION TO ANTI-LOCK BRAKING SYSTEM DIAGNOSIS
M1352012500396
The anti-lock braking system (ABS) operates differ-
ently from conventional brake systems. These differ-
ences include sounds, sensations, and vehicle
performance that owners and service technicians
who are not familiar with ABS may not be used to.
Some operational characteristics may seem to be
malfunctions, but they are simply signs of normal
ABS operation. When diagnosing the ABS system,
keep these operational characteristics in mind.
Inform the owner of the kind of performance charac-
teristics to expect from an ABS-equipped vehicle.
ABS Diagnostic Trouble Code Detection
Conditions
ABS diagnostic trouble codes (ABS DTCs) are set
under different conditions, depending on the mal-
function detected. Most ABS DTCs will only be set
during vehicle operation. Some ABS DTCs will also
be set during the ABS self-check immediately after
the engine is started.
When you check if an ABS DTC will be displayed
again after the DTC has been erased, you should
duplicate the ABS DTC set conditions. Depending on
the detection timing and set conditions for the spe-
cific ABS DTC, you must either drive the vehicle or
turn the engine off and restart it. To set the proper
conditions for that DTC again, refer to "ABS DTC
SET CONDITIONS" for each ABS DTC that you are
trying to reset.
ABS DIAGNOSTIC TROUBLESHOOTING STRATEGY
M1352011100566
Use these steps to plan your diagnostic strategy. If
you follow them carefully, you will be sure that you
have exhausted most of the possible ways to find an
ABS fault.
1. Gather information about the problem from the
customer.
2. Verify that the condition described by the
customer exists.
3. Check the vehicle for any ABS DTC.
4. If you cannot verify the condition and there are no
ABS DTCs, the malfunction is intermittent. Refer
to GROUP 00, How to use
Troubleshooting/Inspection Service Points
− How
to Cope with Intermittent Malfunctions
P.00-6
.
5. If you can verify the condition but there are no
ABS DTCs, or the system cannot communicate
with the scan tool, check that the basic brake
system is operating properly.
• If the basic brake system is not operating prop-
erly, refer to the GROUP 35A, Basic Brake Sys-
tem Diagnosis
P.35A-3
.
• If the basic brake system is operating properly,
refer to
P.35B-86
.
6. If there is an ABS DTC, record the number of the
DTC, then erase the DTC from the memory using
the scan tool.
NOTE: Any DTCs stored in the ABS-ECU cannot
be erased if there is a malfunction.
7. Duplicate the ABS DTC set conditions to see if the
same ABS DTC will set again.
• If the same ABS DTC sets again or the ABS DTC
cannot be erased, perform the diagnostic proce-
dures for the DTC. Refer to
P.35B-11
.
• If you cannot get the same ABS DTC to set
again, the malfunction is intermittent. Refer to
GROUP 00, How to use Troubleshooting/Inspec-
tion Service Points
− How to Cope with Intermit-
tent Malfunctions
P.00-6
.
DIAGNOSTIC FUNCTION
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ON-BOARD DIAGNOSTICS
If the ABS-ECU detects any problem in the CAN
communication line or the ECUs, which the
ABS-ECU is communicating with, it stores a diagnos-
tic trouble code. The DTCs have 26 items. The DTCs
can be confirmed by connecting scan tool MB991958
(MUT-III sub assembly.) The stored DTCs are not
erased even after the ignition switch has been turned
to the LOCK (OFF) position, or the battery has been
disconnected. The DTCs can be erased by operating
scan tool MB991958 (MUT-III sub assembly.)