Electrics: Xenon headlight

[jnmonaghan]

I have factory fit Bi Xenon on my 2003 V70.
What does SUM stand for,and where are they located?

Jude

[Simon Jones]

SUpension Module. Not sure where it is mounted, but the sensors are fixed to the rear suspension arms.

[100K+]

Finally got my Xenons to work how I want :- Both lights now shine up the road on dip beam and not just 3 yards in front of the car.
Both lights now also lift and fall when they are switched on.
I needed to change a rear suspension sensor to get the correct voltage reading so that I could perform a SUM calibration and then fit a new stepper motor to translate that into moving the reflector in the O/S light so that it shone correctly.

Attached is a jpg of my old motor stripped down, and I now have a better understanding (I think) of how these work. The large white geared wheel (LHSide bit )is driven by the motor via the worm drive. The inside of the white wheel is threaded, so that as it turns a central "post" is pushed out or pulled back into the motor. An arm is attached to this central post ( runs back at 8 o'clock) fits into the pin on the slider which can be seen on the PCB (looks like a leg) - that is the bit I'm not sure what /how/why
Anyway, with in the central post is another threaded post which is moved in and out by the 6mm white plastic dome nut on top of the motor.
So there are two methods of moving the reflector in or out, and its the total of how much each piece is moved that gives the reflector its position. If the white wheel bit is fully retracted, regardless of how you screw the 6mm dome nut you are not going to get a good beam pattern.

The motor is a "Johnson" but apart from numbers has no other markings.

When I get 10 minutes I'm going to strip down a motor from my T5 as they appear apart from the post adjusted by the 6mm white nut, externally the same.
I'm not expecting to see the slider attachment on the PCB as i'm sure that has something to do with the auto adjustment of the lights.

Cheers

Bob

[pacman67]

I think you've confirmed what a volvo indi suggested to me that mine will probably be the sensor as I've changed both level motors. Well done.

[100K+]

Originally Posted by pacman67

I think you've confirmed what a volvo indi suggested to me that mine will probably be the sensor as I've changed both level motors. Well done.

During all my messing around with this issue I have read about a "fix" for the rear suspension sensor reading "too high/low". This depends upon how off the voltage of the sensor. The rear left won't allow you to SUM recalibrate unless less than 3.5v

Rather than replace the sensor, remove the " drop link" from the sensor to the chassis. You'll need a thin 10mm spanner to hold while you remove the nut.
Cut 1/2" out of the rod, thread both ends and get a 25mm x 5mm stand off from a PCB. Join the rod together again and you can shorten or lengthen the rod by turning the stand off until you get the correct voltage from the sensor then you can perform a SUM recalibration.
A rear sensor from Volvo cost me £42.00

Good luck

Cheers

Bob

[pacman67]

My sum does successfully calibrate on Vida though.

[100K+]

Originally Posted by pacman67

My sum does successfully calibrate on Vida though.

ouch..... Ok consider as a possibility. The fact you have swapped the old centre pins over to your new motors - suggests these motors came from non-4C suspension cars.??? Volvo told these motors (non 4C)won't work with 4C. They are considerably cheaper too.

Can you remember if the circuit board in your new motors have the "leg" on with the slider on, as shown in my jpeg, as I feel this has something to do with the 4C setup?

My gut feeling is unless you have the correct motors the lights won't rise and fall when 1st switched on. To me the fact that you can do a sum calibration means there are no issues with the rear sensors. The issue is that the SUM module can't /won't talk to the motors. Make some kind of sense??

Cheers

Bob

[pacman67]

Both cars are non 4c, both pcb were identical with the little slider on, the only difference was the pin. I compared my car to a couple of similar year r spec cars and their lights hardly moved on start up, mine appeared the same.

[100K+]

Originally Posted by pacman67

Both cars are non 4c, .

Then I think you should not be doing a sum recalibration to reset your lights. I thought SUM only applied to 4C setups. - (I could be wrong)

Non 4C Xenon lights are controlled via the CEM. but calibration is carried out in the REM (tab diagnostics/vehicle communication/REM.

This info from Vida/information/product spec/35 lighting/GDL/function.

Cheers

Bob

[pacman67]

Sorry mate, yes your right, my wording is wrong, I've done a sensor calibration via the rear module, and all was well.. Will say though light on the road in front of the car is a bit disappointing, lights look very white, just not on the road. Had them rechecked at mot station and they showed me the pattern on the test rig and it was bob on. Maybe a bulb upgrade is needed ?