Body BIW - Active Aero - P14: 720S, 720S Spider - Follow the instructions
available in this article to install an external catch tank in the event of a

customer complaint for persistent issues with the airbrake system even though
MTI0017 has been completed on a previous visit

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Knowledge Base within the McLaren Retailer Portal to verify that this
is the current version.

Vehicles affected:

P14: 720S, 720S Spider

Location: Body BIW - Active Aero

Concern: Airbrake Warning Message On Driver's Display

Condition: Permanent

Diagnostic Trouble Codes
TCU:

C101B92 Airbrake move time out
C101C92 Airbrake movement implausible

C101A94 Airbrake not holding position

Measure

The level of the clutch fluid when is not being pumped around the transmission can
sit lower than the airbrake deploy valve (see image below) within the transmission.

When the engine is running so is the oil pump in the transmission, which will
distribute the oil covering the deploy valve stopping the risk of introducing air.

Airbrake Deploy (Up) Valve

ULI; | EA a

Oil Level (7 Litres)

However, there can be various driving and airbrake deployment conditions that could
still allow the system to pull through clutch fluid and air. The presence of air in this
hydraulic system can result in reduced functionality of the airbrake followed by
airbrake warnings and DTCs being registered as outlined in the ‘Diagnostic Trouble
Codes’ section above.

In order to eliminate the possibility of this occurring, it is advisable to retrofit an
external clutch fluid catch tank. Ultimately, this will allow for an increase in the clutch
fluid fill which will result in a higher clutch fluid level in the transmission without
causing leaks from the breather valve.

Care Point: Prior to the installation of the catch tank, ensure KA-01105 has been
carried out first.

The procedure for installing the catch tank and adjusting the clutch fluid level
accordingly can be found below:

NM

Drain the clutch oil (as per SIS instructions) and measure the quantity

With the transmission still in the vehicle, remove (pull out) the existing breather
valve (No, 8 in the graphic below)

Then remove (unscrew) the plug located at the opposite end (No. 3)

Once both plugs have been removed proceed to the installation of the new
assembly

Push in the No8. end of the breather into the location where the original
breather valve was (removed at step 2)

Then insert the banjo end to the other end (do not torque at this stage), where
the screw was (removed at step 3)

Then insert the middle bit of the assembly (highlighted in yellow) into the casing
of the transmission

Ensure the assembly sits nicely with no tension

Once satisfied that the above steps have been completed successfully proceed
to torque the banjo bolt to 15Nm

10. Then torque both grub screws (No.9) to the casing of the transmission, use

2.5Nm.

11. Ensure No. 8 end is fully inserted

Once the installation is completed, refill the clutch (as per SIS procedure) BUT the
clutch fluid level MUST be increased by 700ml compared to the instructions.

Once the clutch fluid fill procedure, including the increase of 7OOmI, has been
completed carry out the following sequences using the MDS diagnostic tool:

1,

2.

Airbrake bleed sequence
Sleep the vehicle

Airbrake calibration sequence

. Sleep the vehicle

Clear DTCs

Finally test the operation of the airbrake by means of a test drive to confirm
successful completion of the job.

Remove the
clutch breather
from the DCT

This may require
gentle heating
with a hot air
gun to remove

The breather
tank then fits
into the hole

Fit the catch
tank front line
to the front
interface plate
connection
thread

MTI Updates Information

This document is uncontrolled when printed. Before use, check the
Knowledge Base within the McLaren Retailer Portal to verify that this
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