Mazda 6. Manual - part 261
P–100
TROUBLESHOOTING (ABS/TCS/DYNAMIC STABILITY CONTROL)
*
1 : DTC U2021 for past malfunction is not recorded in the ABS/TCS HU/CM. DTC U2021 for present malfunction
displayed, but goes out when engine coolant temperature rises above 0
°C {32F}.
*
2 : When malfunctions happen that display DTCs, flashes the ABS warning light.
2. Precautions during servicing of ABS/TCS
The ABS/TCS is composed of electrical and mechanical parts.It is necessary to categorize malfunctions as
being either electrical or hydraulic when performing troubleshooting.
(1) Malfunction in electrical system
• The ABS/TCS hydraulic unit and control module (ABS/TCS HU/CM) has an on-board diagnostic
function. With this function, the ABS warning light and/or BRAKE system warning light will come on
when there is a problem in the electrical system. Also, past and present malfunctions are recorded in
the ABS/TCS HU/CM. This function can find malfunctions that do not occur during periodic inspections.
Connect the WDS or equivalent to the DLC-2. The stored malfunction will be displayed in the order of
occurrence. To find out the causes of ABS/TCS malfunction, use these on-board diagnostic results.
• If malfunction occurred in the past but is now normal, the cause is likely a temporary poor connection of
the harness. The ABS/TCS HU/CM usually operates normally. Be careful when searching for the cause
of malfunction.
• After repair, it is necessary to clear the
DTC from the ABS/TCS HU/CM memory. Also, if the ABS/TCS related parts have been replaced, verify
that the no DTC has been displayed after repairs.
• After repairing the ABS wheel-speed sensor or ABS sensor rotor, or after replacing the ABS CM (ABS
motor or ABS motor relay or solenoid valve), the ABS warning light may not go off (
*
) even when the
ignition switch is turned on. In this case, drive the vehicle at a speed of more than 10km/h{6.2mph},
make sure that ABS warning light goes off, and then clear the DTC.
* The BRAKE system warning light also illuminates when any rear wheel malformations.
• When repairing, if the ABS/TCS related connectors are disconnected and the ignition switch is turned
on, the ABS/TCS CM will mistakenly detect a fault and record it as a malfunction.
• To protect the ABS/TCS HU/CM, make sure the ignition is off before connecting or disconnecting the
ABS/TCS CM connector.
• To protect the terminal, use the SST (ABS/TCS: 49 G066 001, DSC: 49 G066 004) when connecting
the tester lead to the ABS/TCS HU/CM connector.
(2) Malfunction in hydraulic system
• Symptom in hydraulic system malfunction are similar to those in conventional brake malfunction.
However, it is necessary to determine if the malfunction is in an ABS component or the conventional
brake system.
• The ABS hydraulic unit contains delicate mechanical parts. If foreign materials get into the component,
the ABS may fail to operate. Also, it will likely become extremely difficult to find the location of the
malfunction in the event that the brakes operate but the ABS does not. Make sure foreign materials do
not get inside when servicing the ABS (e.g. brake fluid replacement, pipe removal).
Warning lights that may
illuminate and/or flash
Cases in which the light may
illuminate
Conditions in which the
light will go out
ABS, EBD, TCS and DSC
control
All the following lights
illuminate:
• TCS OFF light
When the engine coolant
temperature is below
0
°C {32 F}.(
*2
)
When engine is started and
engine coolant temperature
rises above 0
°C {32 F}.)
ABS: Cuts control.
EBD: Cuts control.
TCS:
1. If TCS is operating, cuts
control after gradually
released TCS control
value.
2. If TCS is not operating,
cuts control.
All the following lights flash:
• ABS warning light
• BRAKE system warning
light
Following light illuminates:
• TCS OFF light
When confirming DTC,PID/
DATA and ACTIVE COMAND
MODES item using WDS or
equivalent.
When ABS ON-BOARD
DIAGNOSTIC SYSTEM is
released.
ABS: Cuts control.
EBD: Cuts control.
TCS: Cuts control.