V50 (and other P1s?) DIFFERENT Siren Module R&R and Battery Replace (Now With Part 2 - "The Battery") Topic is solved

[packetfire]

My 2010 V50 (and I assume the rest of the C30, C70, S40... so-called "P1" cars) has an "Alarm System Service Required" message on the DIM, and VIDA reported "CEM-DD1B - Communication with SCM control module Signal missing" (SCM = Siren Control Module)

But SURPRISE! The siren is not up above the passenger-side wheel well (alternatively "behind the passenger-side headlight") as it has been for the v70s and other "P2" pre-Ford cars.

So, here's the process, as it is not documented anywhere, and I do not have the time to make a video for YouTube (nor the delusion to think that I can make spare change from YouTube).

It's still on the passenger side, but its just below and in front of the windshield. To get at it, you will remove the cowl:

Pop out the plastic clips circled in red in the photo above by pressing in the center until it slightly detents, then get under the large lip with a fork of a "plastic crowbar" interior tool, and lift up the whole thing. (I replaced mine with slightly more sensible ones from the specialty fastener drawer at Lowes - 1/4-inch size, as mine were broken when the previous owner opened it up, but did not repair anything.)
Next turn the plastic Phillips-head screws (red squares) 1/4 turn to the left (from noon to 9pm) but do not remove them.
Then pop off the plastic covers on the wiper pivot points (yellow circles), and remove the nuts that hold the wiper arms on.
Lift up the wiper a bit, and wiggle the part of the arm that did not bend up with the wiper blade, and the wiper arm will come off easily. (Gotta take the tension off that is holding the wiper blade against the glass.)
Now gently wiggle the entire plastic cowl away, helping it to come free of the area around the hood hinges.

Here's a photo of a plastic phillips-head screw, pointing to 12 noon

The siren module is here - Take off the nut.

And the other nut which is hard to see, up under the ledge in front of the windshield:

Now you can take the metal bracket off the car, flip it on its side, loosen the nuts, and remove the plastic box from the metal bracket. Set it back down in the bracket for a moment, as you can now see the connector latch and pry it gently open with a screwdriver to get the cable off the alarm module plastic box.

Take the box inside, and pry it open with a medium-size flat-head screwdriver. Mine opened up easily. No need to cut anything. Put away that hacksaw.

The circuit board is held in place by 3 plastic tabs that pry back with very little force, and the connectors for the battery and speaker pull straight out, but grab the white plastic connectors, not the wires. You can see the corrosion on my battery pack easily, but there's more corrosion here - look at the leftmost pin of the right-hand connector - it is BLACK.

Pry up gently on the white plastic tab of the connector to free the wire and terminal, and pull gently on the wire to remove the terminal.

You can see in the above that the terminal is also BLACK. Clean them up with emery paper or some MEK or other electrical contact cleaner.

The battery is held in place by a very strong metal clip. Get a flat-blade screwdriver in there, and pry the metal away from the vertical plastic battery bumper, then pull it off with needle-nose pliers.

The very weirdly-shaped battery is a result of poor planning - the box could have been a tiny bit bigger, and held a standard battery, but this one is a custom job.

Not to worry, this "custom job" is nothing but the usual 4 button cells with metal tabs welded to each, in series, to give 4.8 Volts total.
If we cut open the heat shrink that holds the batteries, we find an amusing tale:

The black part on the end is - a SPACER! Yes, the clearances were tight, and they had to take a 4-stacked set of cells and "unfold" them to make a stack of 2 and 2 singletons, but the stack of 2... wasn't tall enough, and needed a SPACER to not rattle around! One can imagine all the miscommunication here, as the battery could have been a stack of 3 and 1 singleton, but nope, add an extra-cost spacer to make it really work in the production plastic "as molded". (The screaming of the engineers on both sides of this debacle can still be heard to echo...)

But what do we replace it with? A STANDARD battery, not another of these mutant things! Just a 4.8 Volt Ni-MH Button Rechargeable Battery with solder tabs, 4.8V 330 mAh will do fine. The dead battery is 4.8 V 240mAh, so any larger milli-amp-hour rating is fine.

We can do one of two things - we can cut the heat-shrink on the new battery, and "unfold" it as was done with the original battery, and then put new heat shrink (or electrical tape) around it to make it fit, or we can make the case slightly thicker by laying down successive beads of silicon caulk to make the lip of the lid about 8mm thicker, and leave the new battery alone. Either way, the red and black wires from the old battery will have to be soldered onto the new battery, and the case wants to close and be waterproof, so the case is going to be sealed with waterproof tape, after the case exterior is cleaned and de-greased.

I'm waiting on the battery to arrive, so I do not have any photos of the new battery installed as yet, but it is a 25mm diameter 35 mm high battery, and the case is 21.66 mm deep and the lid is 5.67 mm deep, so there is a 7.67 mm difference to make up before the case closes, and the case has to close and be waterproof... or perhaps be relocated to inside the cabin, behind the glove box, as I do not intend to plug in the siren speaker, I just want to be free of the error message every time I start the car.

Reassembly has one little trick - there are rubber tabs on the rubbery ends of the cowl cover, and those tabs go UNDER the windshield glass. This photo is taken from above the hood standing at the driver's outside mirror, to show the little rubber tab. Once they are in place on each side, things wiggle into place nicely.

THE NEW BATTERY

The battery came in the mail, so this section is specific to using a cheaper battery than the highly customized one that costs too much. Fair warning, you need a razor knife, some minimal soldering skills, a soldering iron and solder, pliers, small cutters or tiny scissors, electrical tape, Goop brand adhesive, Gorilla tape, and some patience. Here's the battery as it comes.

Gently nick the green plastic at an edge (don’t cut into the metal battery case!), and peel off the plastic cover, to reveal the 4 batteries inside.

If you pull the batteries apart gently, you see that they are connected by thin metal strips, each tack-welded to a battery surface. Move slowly and gently, and you won’t break the welds. If you do, you’ll have to solder them back in place, which is not a big deal, but a 60-watt minimum soldering iron will be required to generate enough heat.

You have to cut the metal tabs so that the battery will "unfold" properly, so pay close attention to the photo below, as you must cut the metal strips (easy to cut, they are thin, even cuticle scissors will do, but don't let your wife catch you using them!), and remove the scraps that are left attached to the batter case with a pair if pliers. Remove the scraps left from BOTH cuts!

As you unfold the battery, tape the metal strips with thin strips of electrical tape, so that the metal strips cannot make contact with both the “+” side (most all of the battery) and the “-“ side (the recessed circle in the top). The area inside the red circle below is the “-“ (“minus”, “negative”) contact area, and the entire rest of the battery, including the area directly outside the red circle is the “+” side (“positive”) contact area, so in this photo, the areas of the metal strip just above and just below the red circle CAN SHORT OUT THE BATTERY. (“DANGER, WILL ROBINISON!”) If the battery feels warm, it is being shorted out, so get the metal tabs wrapped with tape immediately AS YOU UNFOLD.

Here is a taped metal tab. Note that you have a stack of two, and then the other two singleton batteries to the left. All connected in series.

If a tab breaks away from a battery, don't fret, just solder it back on. You can see in the photo below where I had to solder the topmost battery.
The large blob of solder remaining atop the metal tab is how much solder I had between the soldering iron and the tab to maximize the heat transfer between the iron and the metal tab. The solder that did the job is UNDER the metal tab of course, and you can't see it. But adding solder to the "iron side" is what makes the "connection" to allow the soldering iron to heat things up, and once you are done, you don't want to try to remove that "excess solder".

Finish by wrapping the entire battery assembly with more electrical tape, or use a really, really big piece of shrink-wrap, but it you actually have massive shrink wrap for massive cables in your junk drawer, you don’t need me to tell you anything about shorting out batteries, taping, or soldering, do you?

Here is the whole assembly, cut, taped, and with wires soldered to the contact tabs. If the solder points protrude out from the battery (look above at the photo of the battery to see the "solder points" sticking out on my battery) just fold the over back onto the battery, sandwich the wire between them, and then solder, as you don't want them sticking out.

Next, we need to do some case modification for the new battery assembly – the batteries are very likely slightly larger diameter and slightly thicker than the ones that came out of the siren module, so they won’t slide under the semi-circular lip at the right in the photo below. You also need to remove the glue that is on the case under where the battery was. My glue was still flexible, and peeled off.

After cutting away the lip, we have something like the below

And now the batteries fit

If you had to clean the contacts on the connector, you had lifted up on the white plastic tab on the tiny white “molex” plug to remove the corroded connector

To get the cleaned connector to slide in and STAY in, you need to make sure that you have the metal tab (use a magnifying glass to see it) bend slightly out, so that the bent-out metal tab grabs the white plastic tab, and the metal tab stays in the white plastic connector. The metal tab that you bend out is that tiny protrusion at the left of the metal connector - it is perhaps the smallest functioning part of any Volvo that you must adjust, but these connectors are everywhere. Good mechanics have the special "molex pin removal tool" that makes this easier and faster.

Plugged back in to the circuit board, note that I have NOT plugged the siren speaker in, which is the two-prong connector above.

Reassembling the plastic case should be easy, and you may want to re-used that foam spacer, gluing it onto the top of the stack of two batteries. (I strongly endorse “Goop” adhesive for this, it held up from the 1980s to the mid-2000s on my 240 wagon in many applications).
You can sparingly apply more Goop adhesive around the perimeter of the case, which is not gasketed, but has a nice lip. If you gouged the lip anywhere, be sure to seal it with the Goop glue. I additionally ran some electrical tape around the entire perimeter of the box to cover the joint between case and lid, and then ran “Gorilla Tape” cross-ways around the box to act as a clamp while the glue dried, and to reinforce the tight seal.

WARNING – THE METAL BOX
Some variants of this same alarm siren box are enclosed in a shiny metal box of roughly the same shape these are the alarm boxes for the v70s later than 2010, c70s, s40s, etc. They are encased in metal because they are just inside the wheel well either in front of or up and behind the strut.

Those metal cases must be cut off with a grinder, and you may then have to relocate the box to a drier place, which means making an extension cable for the wiring to the box

AN ALTERNATIVE - THE SOFTWARE - ONLY APPROACH

All of this bother and expense, just to get rid of the warning message when you start the car? You've never soldered, and know no one else who ever has? Don't dispair.

Maybe the answer for you is to just admit that no one wants to steal a 2010 Volvo v50, and DELETE THE ALARM IN SOFTWARE. There is a Dealer part number for this software in the VIDA parts list, it is Part 30664430 – “Alarm remove”, described as “To remove the ‘car alarm’ function”

No idea what the stealership charges for this.

[matthew1]

Outstanding, Packetfire. I'll put this in the Repair Database, and I made your account MVS Contributor.

[packetfire]

NB: Updated 8/17/2024 with specifics on the "battery surgery" portion of the job. It just looks complicated because I took so many photos for those who have never tried stuff like this before.

"You Do Not Own That Which You Cannot Maintain and Repair"

[JacksonTNTurbo]

Youre the man Packetfire. Truly a saint!!