smithyzen
Member Since: 03 Feb 2013
Location: wolverhampton
Posts: 2
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Hi, has anyone had a problem with their adaptive headlights ? my left hand headlight is pointing visibly low, The lights do there normal start up routine, ie, self calibrate, but when the right one goes up the left one doesn't. I have swapped the lights over left to right, and the problem stays with the same headlight unit. I have changed the module that is held with 3 screws underneath the headlight unit but it did not cure it. I am thinking that it could be the up down swivel motor in the headlight. I cant see this one from looking inside the lamp unit, only what i think is the left right one.
There are lots of pages on the internet about this problem and some suggest it may be something called the auto levelling module, i attempted to get to this and bottled it when i realized just how difficult it was. My gut tells me its the headlight thats the problem, but before i commit to buying, they are not cheap, has anyone else come across this ?
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Fri Jan 08 2016 5:31pm |
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RRSTDV8
Member Since: 12 Aug 2011
Location: Northamptonshire
Posts: 8982
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I have had this problem with my driver's side headlight. I have noticed that on the odd occasion the headlights will go through the self calibration routine when driving. It's happened twice that I can remember although I doubt it's supposed to do it; I guess it's another symptom of a failing headlight sensor. The fault can often be cleared by restarting the car - the calibration routine is started when the AFS control module receives an "ignition on" signal. Most irritating for me is that the fault is occasional and most likely to occur if the vehicle has sat for a couple of hours after being driven. I think something must just get warm and throw an error.
The problem that causes the beam to point at the ground rather than up the road is a swivel function failure. It's annoying because one can see the light go through the calibration but not then rise to point up the road. Short of taking the headlight apart, I'm not sure that there is cure other than replace the faulty headlight unit. This is what I'm going to try, having sourced some new headlights from a forum member. Hopefully this solves the issue.
Note that there are a number of controllers. The AFS control module is the one on the passenger's A pillar. The AFS power modules are fitted to each headlight unit. It might be worth trying to find a replacement power module for your failing headlight just in case that is the cause. Not sure it will help having read the following:
Quote:
AFS Operation
The AFS controls the swiveling angle of each projector module using speed and steering angle signals. The angles of each
projector module differ to give the correct spread of light, e.g. when turning left, the left hand projector module will have a
greater swiveling angle than the right hand projector module.
Xenon Headlamp Assembly with AFS Construction
The AFS xenon headlamp construction is similar to the non-AFS xenon headlamp assembly. The AFS assembly contains an
additional carrier frame which provides the location for the AFS actuators. The remaining lamps are as described previously for
the xenon headlamp assembly. The functionality of the static bending lamp on the AFS headlamp is different from the
functionality of the cornering lamp on the xenon headlamp.
The carrier frame is attached to the AFS vertical actuator. The projector module has a central pivot point which allows the module
to move horizontally in response to operation of the AFS horizontal actuator.
The AFS actuators are bi-polar (2 phase) dc stepper motors which are driven by a power output from the AFS power module. Each
stepper motor receives its position information from the AFS control module via the applicable AFS power module. When the
actuators are powered to their requested positions, a holding current is applied to maintain the actuator position.
The actuators do not supply a positional feedback signal to the AFS control module. Each stepper motor requires referencing each
time the AFS system becomes active. When the AFS system is active, each vertical actuator is driven in the low beam position
and each horizontal actuator is driven to an inboard position until a mechanical stop in the actuator is reached. Once the stop is
reached a step counter in the AFS control module is set to zero and the actuator is then powered to the operating position as
determined by the AFS control module software.
The AFS control module receives front and rear suspension height data to provide dynamic headlamp leveling adjustment via the
vertical actuator motor. The AFS control module also receives vehicle speed signals from the ABS module to adjust the projector
module vertically to increase the beam range as the vehicle speed increases.
Initialisation Procedure
When the AFS control module receives an ignition on signal, the control module performs the initialisation procedure which
ensures that the headlamps are correctly aligned on both their vertical and horizontal axes.
The headlamp leveling initialisation takes less than 3 seconds to complete. The headlamp leveling motors are powered from their
current position, which can be either the upper or lower limit or somewhere in between, to their lower position and then back to
the 0 degrees position.
The AFS swivel initialisation starts less than 1 second after the headlamp leveling initialisation is activated to ensure that the
headlamps are at or below the 0 degree position in the vertical axis, thus preventing glare to oncoming vehicles. The AFS swivel
initialisation is completed in less than 2.5 seconds. The LH and RH AFS actuator motors are powered from the 0 degree position to
their fully inboard position, then to their fully outboard position and then back to the 0 degree position.
Failure Mode
In the event of a failure of the AFS system, a warning indicator in the instrument cluster is illuminated to warn the driver. The AFS
warning indicator illuminates when the ignition switch is in position (II) and will flash continuously until the fault is rectified. The
AFS warning indicator will also be illuminated if a failure of the steering angle sensor or the vehicle speed signal is detected.
Illumination of the AFS warning indicator does not necessarily mean that there is a fault with the AFS system. The fault may be
caused by a failure of another system preventing the AFS system operating correctly.
The AFS control module performs a diagnostic routine every time AFS is requested. If any fault is found, the AFS control module
will suspend the operation of the AFS function.
If the AFS leveling system has failed with the xenon projector module in a position other than the correct straight ahead position,
the AFS control module will attempt to drive the projector module to a position a small amount lower than the standard position.
If the swivel function has failed, the AFS control module will lower the projector module using the leveling actuator motors to a
position much lower than standard to prevent excess glare to oncoming vehicles.
The AFS control module software can detect an internal failure of the control module control circuits. The control module will
power the projector modules to the zero position and prevent further operation.
Faults can be investigated by interrogating the AFS control module using T4 to check for fault codes. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed
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Fri Jan 08 2016 10:24pm |
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