But the newer Volvos are far more difficult to get up to a million miles due to all the… stuff they’ve added. First, there’s eleventy-seven airbags, and replacing them after an accident would cost more than the car would be worth after only 250K miles, and second, there are nearly as many onboard computers, and while these make diagnosis easy, they are locked to each other in mysterious ways overcome only by stealerships and Ukrainian hackers. My v50 has 16 different modules (green), some can have even more (gray).
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- VIDA Status - Yes, I AM showing off here - nothing to fix, and ready for race day EVERY day.
So, keeping the electronic modules healthy is as central to post-2000 Volvo longevity as changing fluids. What seems to kill them is heat, and problematic CEMs can be fixed by adding heat sinks. One wag even put a 12-volt fan in to blow air across the CEM. (This makes sense, as I worked my way through college by working night shift at IPL Systems out in Waltham, MA supervising the “final test” of the IBM 370 plug-compatible mainframes they made in the 1970s – we’d roll the computers into a room sized oven, start them running continual diagnostics for 48 hours, and turn up the heat to 130 degrees F to stress the chips. If something failed, we’d fix it, and start the 48 hours of “burn in” all over again for that machine.)
Most of the Volvo modules have proven to be very robust, and are best left alone, despite being in the engine compartment, but the CEM which is in the passenger compartment in both v70s and the v50 (and s40, c30, and c70…) and the REM, in the v70s back by the cargo door, are worth some attention.
While the v70 has the CEM above the driver’s feet, the v50 has it above the passenger’s feet. Removal for the v50 is perhaps best shown in the various YouTube videos, such as this one
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but, in short, I suggest the following over and above whatever video you watch:
a) First, unlock all the doors, and open the cargo bay door if you keep your toolkit in the spare tire well, then disconnect the battery. Removing the negative cable is all that is needed, and that’s a 10mm nut. Go away for a while and have a coke or a smoke. Let all the capacitors discharge in all the modules before you mess with anything.
b) Also, after you pull the battery cable, switch the ignition to “Position II” RIGHT NOW so you don’t forget. The impossible-to-reset v70-era SRS light you avoid triggering may be your own, and one must assume that all Volvos suffer this little bug, not just v70s, so NEVER reconnect the battery on any Volvo unless the key is first in “Position II”. Fail to heed my warning at your own peril here, the forums are full of the screams of agony of those who failed to heed these words, and were damned to stealership hell to get the SRS light reset, often the SRS module replaced, which will change the designation to “$R$” forever in your mind. And no, your VIDA and DiCE will not save you here, they are not a surefire way to fix that issue.
c) There is a carpet “roof” to the footwell. Find the two plastic studs holding it at the edge nearest the glove compartment, push in the small center dots with a small torx or Phillips, then pull the carpet down and towards you, and set it aside. Also remove the floor mat, as it will be in the way. The CEM is the white plastic module revealed
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d) One school of thought is to remove the connectors on the underside of the CEM first, and the other is that one should do this after removing the connectors on the top side. Either way it is a bit of a fiddly thing, so look closely at those easy-to-see connectors on the underside, and note that each has a U-shaped bar that pulls toward you to unlock the connector. The bars are locked into place by a tiny protruding bit of plastic in the centerline of the connector, and pushing that in (gently!) with a small torx or screwdriver will make pulling the U-shaped plastic bar easier, and eliminate the need to use force that might break old brittle plastic. You must pull the U-shaped bar back all the way, a full 90 degree rotation, to free the connector.
e) There are two captive thumbscrews that hold the CEM in place. Turn them counter-clockwise to loosen, they will flop down and dangle. The CEM can then fold down for connector removal.
f) Remove the connectors. Don’t worry about labeling them beyond “bottom” and “top”, each is unique, and everything goes back together only one way. This is a cramped situation, so be patient, and take a break from being a contortionist if you get frustrated.
g) Once the cables are off, you then have to push the CEM up and back toward the firewall to get it out this can be a fiddly thing, as you are working blind, and using a little force is OK, as the plastic parts upon which the CEM pivots are robust.
Eventually, you will work the damn thing free, and THEN you will see the shape of the metal bracket, and instantly see how you SHOULD have pushed the CEM up and back to free it from the bracket.
h) If you have added any kluges to your CEM, pull out the Add-A-Circuit fuses attached to your kludge wires, and note down which fuse positions each was in. I have two such wires, for my dashcam “driving” and “parking” power wires.
i) Take the CEM inside, set it down, and take a photo, so you can put back the fuses where they are supposed to go. You don’t want to mess this up, do you? There is a guide on the edge of the CEM that specifies which fuses go where, but a photo is easier to follow.
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j) Now, remove the fuses, with a pair of gently-used needle-nose pliers. If you have a “fuse puller tool” than actually works, great, but I can’t make them work.
k) Also pull the relays out with your fingers – they pull straight out, and they only go back in one way.
l) Remove the 3 screws that hold the case together, but it is still snapped together by internal plastic clips.
This photo shows the opened plastic case, so you can see where the locking tabs are, a flat-blade screwdriver can be used to pry outward near each, and you can slide in a small scrap of cardboard to keep it from re-locking as you work your way around. There are 4 locks on each long side, and 2 locks on each short side, note the protruding white plastic on the bottom part of the case with the circuit board. The plastic is thick and bendy, so this is an easy job. You wont break anything.
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Before going any further, check both sides of the board for any greenish or blackish corrosion on the connectors. If you see any, clean it off with circuit board cleaner (from Harbor Freight or Norther Tool) and an old toothbrush. Remember to also clean the connectors in the car to remove any corrosion on that side, and fix the water intrusion from the firewall entrance or from the classic clogged and leaking sunroof drain). Below is the back side of the board, with the top side connectors, the fuse clips, and a few soldered-in relays.
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I bought a collection of heat sinks intended for hobbyist use pre-provisioned with double-sided adhesive thermal tape, (“102pcs Heatsink Kit with Conductive Adhesive Tape, Cooler Heat Sink for Cooling Raspberry Pi VRM VRAM CPU GPU VGA Small IC Laptop LED MOSFET Transistor SCR Voltage Regulator”) on Amazon with multiple sellers, and I separately bought 20mm x 20mm by 10mm high heatsinks, also with self-adhesive tape, for the 2 “big” chips, as I remembered all these chips from my v70.
Look around on eBay and Amazon, I bought a set of 10 of the 20mm x 20mm heat sinks for less than some people wanted for a single heatsink. All told, I spent $20 on heatsinks.)
What sizes are needed? I ended up using these common sizes:
20x20 x 10mm high for the 2 big processor chips
15x10 x 5mm high for the rectangular 15 x 7mm chips and 12 x 7 mm chips
9x9 x 5 mm high for everything smaller (anything with 3 legs or more)
One very small chip is close to a case-closing screw, so I had to cut a 9x9 in half with a hacksaw you can see it in the last “finished” photo, as it is blue, very narrow, and some of the blue has been scraped off in cutting.
Depending upon the set of heatsinks you have, you may have “height issues” with the taller ones, so sort your heatsinks out by height/width size (color does not matter, they are all aluminum) and then sort them further by thickness. You’ll want to use the thinnest ones first.
Regardless of their height, to make room for the heatsinks, you will have to remove the cross-ribs in the plastic top of the case. This is easy, just cut with a carpet knife or diagonal cutters at each intersection, and then bend the plastic back and forth with pliers – it will snap off fairly cleanly in one or two bends.
But do NOT break off the stand-offs, those are the plastic stand-alone pins that protrude from the case. Only remove the plastic ribs. See below for items and areas to leave alone (circled yellow), and ribs to be removed (red)
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Once you have removed the ribs, put the case back onto the circuit board, and note how it extends to just below the bottom of the two circuit boards as in the photo below. As you add heat sinks, you want to test to make sure that they are not “too high”, and prevent the case from fitting down evenly all the way 'round the outside edges in reference to the circuit board. If you set a heat sink atop a chip, and lower the plastic cover down to test, you will verify that you are in the clear before you peel off the cover plastic from the adhesive.
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Here are the two large processor chips with their heat sinks. This is all most people ever do…
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…but we aren’t “most people”, are we? No! Let’s be MORE proactive!
The below shows the 25Amp “Smart Highside Power Switches”, each with a silver heatsink. 25 amps is a lot of current, so putting heat sinks on these seems… prudent.
Note that the alignment of the heatsinks allow “upward” airflow between the ribs of the heat sinks, so orientation should be as shown for all heat sinks. If the heat sinks are slightly larger than the chip or power transistor, that’s OK. The adhesive tape will keep the heat sink from shorting out any connections, and the top surfaces of all the packages are well above (several millimeters) the metal leads from the devices.
But, note well, do NOT use a heatsink **SMALLER** than the top surface of the chip or device. You don't want to cool only PART of the chip, and let the "other end" get overheated. That would create a "thermal cutout switch", as used in gas dryers. It would make the chip fail far sooner. So, first, do no harm!
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But wait, there’s more!
As you have a large collection of heat sinks, why NOT put one on every chip and power transistor? Its simple, anything with more than 2 legs generates heat, so a heat sink can help, and certainly cannot hurt. This looks like the below
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Note the one very small blue heat sink at center. I had to cut it in half with a hacksaw to get the overhang on this tiny chip out of the way of the plastic screw recess in the plastic lid. This was the only chip that was near enough to anything “structural” to make a problem, as the standard 9x9 heat sink got in the way.
Reassemble the CEM, plug the fuses and relays back in, and go put it back in the car. Wiggle it onto the support brackets before you struggle with re-attaching the cable connectors. Flip the CEM back up into place, tight the thumbscrews, and CHECK THE IGNITION TO MAKE SURE IT IS IN “POSITION II”!!!!
Now reconnect the battery, and you can start the car, attach your VIDA DiCE and verify that you have no errors, whatever you please. You are done, and your chips will run much cooler.
This will without a doubt extend their useful life, and if the v70 experience is any guide, the random glitches causing random, multiple serious alerts claimed to be brake system, transmission, and SRS tend to start on hot days about 10 years after the car was new at the earliest for cars not equipped with heat sinks early on.