Diagnostic Trouble Code: B1A85-96 (28)

[Land Rover Joe]

Tribe,

I am looking for some assistance with a consistent DTC I am receiving using my GAP Tool when running diagnostics.

It is from the IPC—Instrument Panel, DTC # B1A85-96 (28): "Ambient light sensor circuit component failure – internal failure."

Image from the GAP tool below.

The workshop manual notes (image below): "B1A85-96 Ambient Light Sensor - Component internal failure. Internal light sensor failure. Check the harness connector to the Instrument Cluster for security and integrity. Clear the DTC and retest the switch function. If the problem persists, renew the Instrument Cluster. Refer to the warranty policies and procedures before renewing the module."

I thought maybe I had a bad "Ambient Light Sensor" (which is located above the dash on a square black plastic tray/counsel on my LR4 in the middle of the truck directly under the windshield). I therefore replaced that sensor in my usual shotgun approach...to no avail.

Perhaps the ground needs cleaning but I am unsure which ground this sensor is routed and perhaps it is from something else. Perhaps the replacement part/sensor is junk (superficially they look fine). Or perhaps my GAP tool is misreading this particular error.

Any insights, experience, or advice would be most welcome!

 

[Rover Range]

Do you actually have an issue, caused by this DTC?

 

[Land Rover Joe]

Thanks @Rover Range -

No and Yes.

I don’t notice anything in particular regarding "ambient light" but I don’t really know what this sensor does.

Something worth noting, however, is that I have another consistent fault which may be related: "HCMB—Headlamp. U0415-00. Invalid data received from ABS control module."

I thought I may try replacing the light sensor to narrow down what is going but that obviously didn’t work.

But that probably didn’t work, because I probably purchased the wrong part (from eBay): 2010-2016 LAND ROVER LR4 HSE L319 - DASH SUN Light / Sunlight Sensor ($34.99) Item number: 146265113487.

From more research, it appears that the Ambient Light Sensor (inside the rear-view mirror module) is NOT the same as the Sunlight Sensor (on the dash). Oops.

In the diagram from the Workshop Manual attached, one can see the “Ambient Light Sensor” (with “High Beam Assist” annotated, #2).

Back to your question: my automatic windshield wipers don’t work (which doesn’t really bother me much) but I also think my automatic, ADAPTIVE FRONT LIGHTING SYSTEM (AFS), is not working properly (which bothers me a bit more).

I say that because the lights used to dip down, and then up, upon start up, which they no longer do. I also think that the “High Beam Assist” function doesn’t work (which I haven’t been using for some time).

All that said, my 2011 workshop manual (in the External Lighting section) says this:

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 is in accessory power mode or ignition power mode 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 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 xenon projector module to the zero (straight ahead) position. If this is not possible, the AFS control module will lower the projector module using the leveling actuator motors 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 an approved Land Rover diagnostic system to check for fault codes.

I don’t have any AFS fault codes or the AFS warning indicator.

However, I keep getting these two DTC codes U0415-00 & B1A85-96 and suppose they are interrelated, perhaps with the AFS or something.

Or perhaps not?

That is what I am trying to get to.

Let me know if that makes sense (or not) -

 

[Rover Range]

If you have an aftermarket windshield, it can cause all the issues you've described.

#2 sensor controls the high beam assist.

 

[Jimmy Brooks]

Thanks @Rover Range -

No and Yes.

I don’t notice anything in particular regarding "ambient light" but I don’t really know what this sensor does.

Something worth noting, however, is that I have another consistent fault which may be related: "HCMB—Headlamp. U0415-00. Invalid data received from ABS control module."

I thought I may try replacing the light sensor to narrow down what is going but that obviously didn’t work.

But that probably didn’t work, because I probably purchased the wrong part (from eBay): 2010-2016 LAND ROVER LR4 HSE L319 - DASH SUN Light / Sunlight Sensor ($34.99) Item number: 146265113487.

From more research, it appears that the Ambient Light Sensor (inside the rear-view mirror module) is NOT the same as the Sunlight Sensor (on the dash). Oops.

In the diagram from the Workshop Manual attached, one can see the “Ambient Light Sensor” (with “High Beam Assist” annotated, #2).

Back to your question: my automatic windshield wipers don’t work (which doesn’t really bother me much) but I also think my automatic, ADAPTIVE FRONT LIGHTING SYSTEM (AFS), is not working properly (which bothers me a bit more).

I say that because the lights used to dip down, and then up, upon start up, which they no longer do. I also think that the “High Beam Assist” function doesn’t work (which I haven’t been using for some time).

All that said, my 2011 workshop manual (in the External Lighting section) says this:

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 is in accessory power mode or ignition power mode 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 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 xenon projector module to the zero (straight ahead) position. If this is not possible, the AFS control module will lower the projector module using the leveling actuator motors 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 an approved Land Rover diagnostic system to check for fault codes.

I don’t have any AFS fault codes or the AFS warning indicator.

However, I keep getting these two DTC codes U0415-00 & B1A85-96 and suppose they are interrelated, perhaps with the AFS or something.

Or perhaps not?

That is what I am trying to get to.

Let me know if that makes sense (or not) -

I’ve had this fault for years, both codes and everything. I’ve never had an issue or noticed anything wrong, everything works as it should. If I didn’t see the code I would have no idea it existed.

 

[Land Rover Joe]

Thanks @Jimmy Brooks and @Rover Range !

And I did have to put an aftermarket windshield in a long time ago...not realizing it would cause any problems like this.

A follow up question for @Rover Range : I assume this means that the AFS is disabled and the auto windshield does not work because of this windshield issue?

Many thanks again!

 

[Rover Range]

It can.
With the wipers in auto. You should be able to spray some water on the windshield and active the wipers.

Also, the high beam assist sensor could be blocked by a toll tag sticker.
The aftermarket windshield could be diffusing the light away from the sensor in the front of the mirror.

 

[powershift]

I've been wanting to swap out my windsheild to a version without the heating elements. Did you get a yellow or red bang on your dash from the windshield or is it a code that is only seen with a reader?