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38C-3
MR-413-X44-38C000$047_eng.mif
V1
ANTI-LOCK BRAKING SYSTEM
Fault finding - Introduction
MK70 ABS
Vdiag No: 04
38C
3. REMINDERS
Procedure
To run diagnostics on the vehicle computers, switch on the ignition using the key.
Faults
Faults are declared as either present or stored (depending on whether they appeared in a certain context and have
disappeared since, or whether they remain present but have not been diagnosed within the current context).
The present or stored status of faults should be taken into consideration when the diagnostic tool is switched on
after the + after ignition feed (without any system components being active).
For a present fault, apply the procedure described in the Interpretation of faults section.
For a stored fault, note the faults displayed and apply the instructions in the Notes section.
If the fault is confirmed when the instructions in the Notes section are applied, the fault is present. Deal with the
fault.
If the fault is not confirmed, check:
–the electrical lines which correspond to the fault,
–the connectors on these lines (corrosion, bent pins, etc.),
–the resistance of the component detected as faulty,
–the condition of the wires (melted or split insulation, wear).
Conformity check
The aim of the conformity check is to check statuses and parameters that do not produce a fault display on the
diagnostic tool when they are inconsistent. Therefore, this stage is used to:
–carry out fault finding on faults that do not have a fault display, and which may correspond to a customer
complaint.
–check that the system is operating correctly and that there is no risk of a fault recurring after repairs.
This section gives the fault finding procedures for statuses and parameters and the conditions for checking them.
If a status is not behaving normally or a parameter is outside the permitted tolerance values, consult the
corresponding fault finding page.
Customer complaints - Fault finding chart
If the test with the diagnostic tool is OK but the customer complaint is still present, the fault should be processed by
customer complaint.
A summary of the overall procedure to follow is provided on the following page in the
form of a flow chart.
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38C-6
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V1
ANTI-LOCK BRAKING SYSTEM
Fault finding - Introduction
MK70 ABS
Vdiag No: 04
38C
Visual inspection of the sealing:
(Only for watertight connectors)
●Check for the seal on the connection (between the 2 parts of the connection).
●Check the seal at the back of the connectors:
–For unit joints (1 for each wire), check that the unit joints are present on each electrical wire and that
they are correctly positioned in the opening (level with the housing). Check that plugs are present on
openings which are not used.
–For a grommet seal (one seal which covers the entire internal surface of the connector), check that
the seal is present.
–For gel seals, check for gel in all of the openings without removing the excess or any protruding
sections (it does not matter if there is gel on the contacts).
–For hotmelt sealing (heat-shrink sheath with glue), check that the sheath has contracted correctly on
the rear of the connectors and electrical wires, and that the hardened glue comes out of the side of
the wire.
●Check that there is no damage to any of the seals (cuts, burns, significant deformation, etc.).
If a fault is detected, repair or replace the wiring (see Technical Note 6015A, Repairing electrical wiring, Wiring:
Precautions for repair)
5. FAULT FINDING LOG
You will always be asked for this log:
–when requesting technical assistance from Techline,
–for approval requests when replacing parts for which approval is mandatory,
–to be attached to monitored parts for which reimbursement is requested. The log is needed for
–warranty reimbursement, and enables better analysis of the parts removed.
6. SAFETY INSTRUCTIONS
Safety rules must be observed during any work on a component to prevent any damage or injury:
–check the battery voltage to avoid incorrect operation of computer functions,
–use the proper tools.
It is forbidden to carry out a road test with the diagnostic tool in dialogue with the ECU because the ABS and
Electronic Brake Distribution functions are deactivated. Braking pressure is identical on both vehicle axles
(risk of a spin under heavy braking).IMPORTANTIMPORTANT
Any fault on a complex system requires thorough fault finding with the appropriate tools. The
FAULT FINDING LOG, which should be completed during the procedure, enables you to keep
track of the procedure which is carried out. It is an essential document when consulting the
manufacturer.
IT IS THEREFORE MANDATORY TO FILL OUT A FAULT FINDING LOG EACH TIME FAULT FINDING IS
CARRIED OUT.
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38C-43
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V1
ANTI-LOCK BRAKING SYSTEM
Fault finding - Interpretation of faults
MK70 ABS
Vdiag No: 04
38C
DF188
PRESENT
OR
STOREDBRAKE LIGHT SWITCH CIRCUIT
1.DEF: Inconsistency
NOTESConditions for applying the fault finding procedure to stored faults:
Clear the stored fault, carry out a road test at a speed of > 36 mph (60 km/h) and test
the brakes using ABS. Use the interpretation of the fault if it recurs.
Special notes:
The fault is detected if the computer does not detect a brake lights switch status
change for 4 acceleration/braking cycles and/or the contact is closed for over
6 minutes with the vehicle speed above 24 mph (40 km/h).
Using the diagnostic tool, check on the statuses screen that ET017 Brake pedal recognises the depressed and
released positions of the brake pedal.
If the pedal position is not detected, use the interpretation of ET017.
If the fault is still present, contact the Techline.
AFTER REPAIRClear the computer fault memory.
Carry out a road test followed by another check with the diagnostic tool.
ABS_V04_DF188