Electrics: Headlight service required - active light issue

[Pablp]

Morning all,

I've had an issue with my 08 D5 XC90 since purchase (second hand).

Headlight Failure - Service Required appears on the dash from the moment I start the car - it can be cleared away on Vida/Vdash but will return almost as soon as the car is started.

Both aims were very low when purchased I the car - I reset this and they now appear good.

Error code - HCM-E010 - Control module Voltage too low.

I've tested the HCM lights within Vida and they sweep left, right, up and down so don't suspect it to be an issue with the motors. I've checked with a spare headlamp and this worked also.

Checked fuses and all appear good, cleaned contacts etc.

One of the HID does have a slight flicker but i'm suspecting the bulb is almost EOL. i Swapped the HCM from right to left and the flicker stopped however..

Can I just replace one of the HCM's located under the headlight? if so which one is Vida referring to - voltage low?

The car has had a new battery recently and when testing is plugged into a 20a tender.

Any other advice is welecome.

Thanks, Pete

[gmonag]

You are confusing modules. The HCM is under the drivers seat according to the wiring diagram. I think you swapped the ingnitors.

A Google search produced this:

Volvo DTC HCM-E010
Make:
Volvo
Code:
HCM-E010
Definition:
Control Module. Voltage Too Low
Description:
The Headlamp Control Module (HCM) checks its own system voltage by comparing the DC voltage to the system voltage in the Central electronic module (CEM). Information about the system voltage in the Central electronic module (CEM) is transmitted via CAN to the Headlamp Control Module (HCM). The diagnostic trouble code (DTC) is stored if the control module detects that: Direct voltage to control module is lower than 9.0 V. The control module's test for the diagnostic trouble code (DTC) starts in the event of: Ignition switch position II. Note! The control module can only detect the fault once the test has been started and the diagnostic trouble code (DTC) is stored when the conditions are met.
Cause:
Contact resistance, oxidation or open-circuit in the terminals.
Low battery.
Short-circuit to ground in the power supply.
Damaged fuse.

[Pablp]

Ah, thanks for that.

I've found the module (really buried under the floor of the passenger seat).

It's most certainly water damaged (connections looked slightly tarnished) and I've opened up the HCM to a sorry sight. I'm assuming this can't be saved.

https://photos.app.goo.gl/Q9W833uGsVgETqaNA

If/when I find a replacement will it need coding to the car? I'm sure I can do this with vdash for a small fee.

Thanks, Pete

[NMB]

Originally Posted by Pablp

Ah, thanks for that.

I've found the module (really buried under the floor of the passenger seat).

It's most certainly water damaged (connections looked slightly tarnished) and I've opened up the HCM to a sorry sight. I'm assuming this can't be saved.

https://photos.app.goo.gl/Q9W833uGsVgETqaNA

If/when I find a replacement will it need coding to the car? I'm sure I can do this with vdash for a small fee.

Thanks, Pete

Hi Pete,

I would imaging that you can just swap this module without any coding to the car as its job is to control the headlights which you have fitted - I therefore expect it to just plug and play.

Re the water damage - i'd look to find the cause for the water ingress to the module. Have you got a sun roof?

[Pablp]

I'm looking for a module but not having much luck within the UK, I'm not looking to spend hundreds fixing this. Perhaps looking for a car being broken.

Yes, I have a sunroof so will find time to look. I know the AC has two drains within the passenger footwell (which has been getting plenty of use the last few days) also.

Thanks, Pete

[currymunster]

Originally Posted by Pablp

I'm looking for a module but not having much luck within the UK, I'm not looking to spend hundreds fixing this. Perhaps looking for a car being broken.

Yes, I have a sunroof so will find time to look. I know the AC has two drains within the passenger footwell (which has been getting plenty of use the last few days) also.

Thanks, Pete

Hi, I would try and clean the board of all the rust.
And try to resolder some of those joints.
It's working okay it's just got as short which rust will do.
Give it as try.... You've got nothing to lose.
Failing that a local radio repair or PC repair place.
Good luck 🤞😂

[Pablp]

Originally Posted by currymunster

Hi, I would try and clean the board of all the rust.
And try to resolder some of those joints.
It's working okay it's just got as short which rust will do.
Give it as try.... You've got nothing to lose.
Failing that a local radio repair or PC repair place.
Good luck 🤞😂

I do have the basic soldering kit/knowledge required so I agree, it's worth a shot.

I'll research the components required and get to work, I'll update with my tale of woe I'm sure.

[SwissXC90]

With such relatively minor water damage the way forward is:

Use isopropyl alcohol and a toothbrusch, clean the board gently
Let dry at least 1 hr (isopropyl evaporates fast in air)
Refit to car and check operation

If it still fails, repeat a couple of times before giving up.

I worked a lot in board level repair and did a lot of water damage repair. If you are lucky and the damage is minor, cleaning the board will resolve the issue, IF the issue is caused by conductive water deposits causing the electronics to misbehave.

Only once the board is clean and dry and still fails, should you start diagnosing electronic problems. As the board is full of surface mount electronics, you may find it difficult to solder / desolder and to obtain any replacement parts.

If the damage has caused corrosion which has eaten away at the copper tracks, then it is beyond repair by any normal person. In that case, replace it.

If the board has electrically failed, I recommend a 2nd hand board from a wreckers. Ensure part numbers match!

I believe the HCM is not coded to the car.

[Pablp]

Originally Posted by SwissXC90

With such relatively minor water damage the way forward is:

Use isopropyl alcohol and a toothbrusch, clean the board gently
Let dry at least 1 hr (isopropyl evaporates fast in air)
Refit to car and check operation

If it still fails, repeat a couple of times before giving up.

I worked a lot in board level repair and did a lot of water damage repair. If you are lucky and the damage is minor, cleaning the board will resolve the issue, IF the issue is caused by conductive water deposits causing the electronics to misbehave.

Only once the board is clean and dry and still fails, should you start diagnosing electronic problems. As the board is full of surface mount electronics, you may find it difficult to solder / desolder and to obtain any replacement parts.

If the damage has caused corrosion which has eaten away at the copper tracks, then it is beyond repair by any normal person. In that case, replace it.

If the board has electrically failed, I recommend a 2nd hand board from a wreckers. Ensure part numbers match!

I believe the HCM is not coded to the car.

Thank-you for the information Swiss.

I did clean the contacts up as best I could given the time available, I'm more hopeful now that multiple attempts could actually bring this back to life.

I did see the colour bands on the resistors which will help with finding the parts. I've not had any luck with breakers online but could check my local yard.

Is this part fitted to other models? I'd imagine it's the same across Volvo's with active bending lights of this vintage?

Thanks, Pete

[SwissXC90]

Google the part number to see what matches you get, that will tell you what it is fitted to