LH low beam not working - 05 XC70 Topic is solved

Post by **vtl** » 25 Jul 2026, 12:00

I don't know if CEM has one relay for headlights or two. If two, it can't be one of these big black relays, as one powers BCM - the one that went belly up in my case. Here's two pairs of smaller relays that L-shaped CEM has:

Post by **cn90** » 25 Jul 2026, 12:27

@vtl,

Are you saying Tyco V23086 C1021 A502 is the HL bulb relay?
If true, then these relays are available on eBay.

It seems to be correct if you look into the V40 video:

Post by **scot850** » 25 Jul 2026, 16:54

I don't believe wither of these are the correct images (happy to be corrected). The relays on various how too, look like this and they seem to have 2 options, one which is a plug in (not what is needed) and a 2nd option which has multiple pins for surface mount:

https://datasheet4u.com/datasheets/TE/V ... 455/752910

You can see both options on this data sheet.

Hopefully this link is clearer to see for a 2005-09 P2 CEM:

https://volvoforums.com/forum/volvo-s60 ... id=1&pid=1

Neil.

Post by **vtl** » 25 Jul 2026, 20:29

My pictures are of CEM from 2005 XC70.

Post by **scot850** » 26 Jul 2026, 10:12

Hm. Mine were from someone repairing one? Strange. I guess we won't know until we crack it open. But thanks for that info as I'll research those part numbers for availability. I wonder if they got the year wrong. Possibly a 04?

If only one light goes out, it would tend to suggest there may be 2 relays. Maybe a redundancy in case one fails you still have one light?

Neil.

Post by **vtl** » 26 Jul 2026, 10:27

scot850 wrote: 26 Jul 2026, 10:12 Hm. Mine were from someone repairing one? Strange. I guess we won't know until we crack it open. But thanks for that info as I'll research those part numbers for availability. I wonder if they got the year wrong. Possibly a 04?

If only one light goes out, it would tend to suggest there may be 2 relays. Maybe a redundancy in case one fails you still have one light?

Neil.

Model Year 2005 started in summer of 2004 and ended in summer of 2005 (in August, I think).

Basic safety redundancy is very Volvish, I would expect it to have a redundant electric circuit for lighting.

Post by **scot850** » 26 Jul 2026, 17:55

Well, We have taken a running car to a non-running car!

Although the car is an 05, the cover on the top of the CEM is of the older style, so we had hope of no corrosion on the smaller connector.

However, there was a lot of corrosion. Looks like what we thought were dummy/non-existing pins, were actually (as we have now found) are actually broken off/corroded off pins. They are the control wire for the alternator, and the windshield wipers...!!

So we now have a working headlight, but a broken car. I don't think Xemodex replace the connectors on the CEM. So it looks like I have to find a good working CEM for this car.

Neil.

Post by **vtl** » 26 Jul 2026, 19:38

scot850 wrote: 26 Jul 2026, 17:55 Well, We have taken a running car to a non-running car!

Although the car is an 05, the cover on the top of the CEM is of the older style, so we had hope of no corrosion on the smaller connector.

However, there was a lot of corrosion. Looks like what we thought were dummy/non-existing pins, were actually (as we have now found) are actually broken off/corroded off pins. They are the control wire for the alternator, and the windshield wipers...!!

So we now have a working headlight, but a broken car. I don't think Xemodex replace the connectors on the CEM. So it looks like I have to find a good working CEM for this car.

Neil.

You can clone it yourself. m16c-flasher.de + USB-TTL adapter for flash and hot air/soldering iron for EEPROM chip.

Vova585 · Post by **Vova585** » 26 Jul 2026, 21:39

vtl wrote: 26 Jul 2026, 19:38
scot850 wrote: 26 Jul 2026, 17:55 Well, We have taken a running car to a non-running car!

Although the car is an 05, the cover on the top of the CEM is of the older style, so we had hope of no corrosion on the smaller connector.

However, there was a lot of corrosion. Looks like what we thought were dummy/non-existing pins, were actually (as we have now found) are actually broken off/corroded off pins. They are the control wire for the alternator, and the windshield wipers...!!

So we now have a working headlight, but a broken car. I don't think Xemodex replace the connectors on the CEM. So it looks like I have to find a good working CEM for this car.

Neil.
You can clone it yourself. m16c-flasher.de + USB-TTL adapter for flash and hot air/soldering iron for EEPROM chip.

I am so impressed with your knowledge and expertise! Mad respect!

Post by **scot850** » 26 Jul 2026, 23:24

Or I can find a connector and swap it over. I will speak to Xemodex tomorrow, and depending on what they say, I feel a junkyard may be in my future. It would be great if I can find one without a bad set of pins and transfer the connector.

My confidence in myself for transferring an eeprom is not high enough to try that, but I love the idea though. I will post a couple of pictures tomorrow as I hope to try and remove the CEM. The hard part of getting it out from under the dash has still to be done!

As far as I can see, all 05-09 P2's and also many years of the XC90 also did. Another option is buying one off Ebay or the likes.

Neil.