Deathtrap

[ASt85]

IMHO so many "hi-tech" uses of processors ignore the basic heat generation problems associated with their use - a prime example is the power control/supply in LED TVs......TVs written off instead of replacing the heat damaged resistors/capacitors - cost of replacement components less than a pound, time used less than 10 minutes - replacement cost of TVs under warranty/guarantee & etc hundreds....but it doesn't fit the current business model to maintain profits.

[R-P]

Just had the issue resurface. Drove in 30C temperatures for 300km. No issues. Parked my car in the full sun and went to put something in it half an hour later.

But the remote central locking wouldn't open the car! Opened it manually with the key.

Turned the key in the ignition, display/dashboard would come on (albeit slightly dimmed) and turn off after 5 seconds. Seemed like a timer trying to establish communications or so and give up after a few seconds and turn OFF the power to the display.

Returned to the car hours later (after dark), but still no display. Drove home 300km without indicators (!!!) and with my phone as (GPS) speedometer. About 50km in, I stopped to see if it had cooled down AND tried to see if my fuelconsumption had worsened because it is clearly running in some powerstarved mode (accelerating from standstill is even worse than normal, once it is going, power is OK), but the ~5 seconds the display works, were too short to read them out. (I managed close to 5liters/100km on the way there by staying under 100km/h, do remember mine ia an auto AWD with issues, so 5l/100km is unbelievably frugal for me)

Unhooked the PLUS cable under the hood the next day (beware that you don't touch e.g. the hood with the wrench !!!!!*) and everything is fine again.

I filled up before going on this 2x300km trip and the odometer and the tripmeter are only 300km instead of 600km higher!!!!!!!!!

My cooling works while driving, but when stood still it can still overheat. And I don't have a solution for this yet, apart from leaving my 13mm wrench in the car from now on.


* Normal way of unhooking a carbattery is unhooking the negative side ON the battery. That way, if you manage to touch the batterypole AND the car's chassis with your wrench at the same time, you are just shorting the negative pole to the chassis, which is what all cars do all the time anyway** with the earthstrap/cable of the battery to the chassis. But touching the POSITIVE side of the battery with your wrench and accidently also touching the chassis is simply shorting the battery: hundreds of amperes will now flow through the wrench. If you are lucky, you will only get some burns. Worse could be your car burning down, you loosing your eyesight due to melted metal flying around, etc. So please be extremely careful whenever attempting this and use an insulated wrench at the very least.

** There are cars that 'ground' to the chassis with the positive pole of the battery, but as far as I know, there are only a handful and they will be 75 years old or older, before the whole world agreed that grounding the negative terminal was more logical and a good way to standardise everything.

[traebbe]

Hi,
think your Problem belongs to a faulty reconnect of the battery.
I had several issues, till i do it this way:
Open the luggages door, turn all actors off (set clima to off, turn off the cabin fan) then turn ignition off.
Wait about 10 minutes to let the system shut down.
Then disconnect both cables from the battery.
Put the plus and minus-cables together to unload all power from the car.
wait another 10 minutes, take a coffee or beer, then turn the key into position II (ignition on)
Put the plus-cable to the battery
then put the minus-cable to the battery.
wait five minutes with ignition on, meanwhile you can put back the battery-cover.
Turn ignition off.
Start the engine and see what happens.
Turn the engine off, close all door.
Lock and unlock the drivers door with the key three times in between 30 second.
Now your fob should work again and the doors should been cleared to get them opened.

Glad to hear your feedback.

Regards

Joachim

[R-P]

Thanks for your input. What is this procedure you are quoting?

I will never say you are wrong, I know too little of the precise problem, but I really think my issue is simply this overheating CEM. And it functionss without issue as soon as it is reset.

Until the temps run too high again.

It failed again today (it has been exceptionally hot once again today: close to 30C).
I think I will hook up the fan to the constant 12V instead of the switched 12V. The 50mA (or less, will measure first) that this fan draws, should pose no problem for the battery unless I leave it for weeks.

If anyone has the schematics of the CEM, that would be awesome. As I have the fanwires running all the way to the cigarette lighter, so about 1meter of wire, whereas I am pretty sure I could use the empty slots on the CEM (or even the used slots by soldering the wires to one of the relays).

[R-P]

To MODs: I thought Volvoforums resized automatically, but it doesn't seem to do it in Edge right now (and logging in in Firefox is impossible for some reason). If this causes issues, just delete the pics and here's a link to the album https://imgur.com/a/Cl0nevn: Every pic starting with "Round2" has an explanation under it. I haven't found how to link pics from an album in smaller size

Round 2:
Bare processor and ROM

Shims on ROM to get them to the same height as the processor

Wedging the heatsink in place with shims and superglue. Under the heatsink is only heatsinkpaste (and the two copper shims with more heatsinkpaste)

Slight slit under metal housing that should provide some airflow


Lid on or off (metal lid will be left off).



Sliding the CEM in its housing (while missing two lids to improve airflow)

Note the two relais that are seen on the right: after finishing up and hooking up the battery again, these relais got hot! Not too hot to touch, but clearly a lot hotter (~35C?) than the surrounding relais and plastic! (25C?)

Note the red and black dot made with a marker to locate the +12V and the GND connectors for the fan lateron. Since most relais are not placed back, they are easily found in this pic should anyone else ever want to see if he can use them on his car too. I just used standard male 6.3mm sliders (I think).


Found two points on the CEM that seem to be connected to the battery (also tested with diode/continuity tester). It does run 24/7 @40mA which is about 1Ah a day on the 100Ah battery. On top of the standby currentdraw that I didn't measure. Just running the car once a month should prevent any issues.

[oragex]

Is that corrosion in there? By the way, to resize the pics there are some little free software available, or simpler I use Paint to open the pic, then zoom in to reduce size, do a PrintScreen, cut and paste again in Paint then save. A bit of a work but not bad

[ma70]

Originally Posted by oragex

Is that corrosion in there? By the way, to resize the pics there are some little free software available, or simpler I use Paint to open the pic, then zoom in to reduce size, do a PrintScreen, cut and paste again in Paint then save. A bit of a work but not bad

I didn't notice any corrosion in the pics but, given the drive-into-a-lake idea, water damage would be ironic! (and if there is corrosion then that could be a cause for concern yes)

[R-P]

I don't think I have waterdamage. Or watercooling
Many others do have waterdamage on their CEM I think.

Originally Posted by oragex

By the way, to resize the pics there are some little free software available, or simpler I use Paint to open the pic, then zoom in to reduce size, do a PrintScreen, cut and paste again in Paint then save. A bit of a work but not bad

Luckily I know how to resize pics, but thanks. The issue is as follows:

I normally upload (full resolution) pics to Imgur (after the previous two sites I used stopped working, I still have to restore my rear-wiper thread on here due to this whenever I locate the pics on some old harddisks...).

Works like a charm and I have the option how large a thumbnail I want to post. It is brilliant!

But when using this site for hosting, all kind of people start commenting on the pics, asking questions, making remarks, etc. I just want to use the site for hosting pics I use elsewhere, like here!
And I can, but only if I put them in a Private Folder. And then you loose the possibility to only link a smaller thumbnail.

So:
1: I am missing something in the options on the Imgur site, or
2: I post them publicly and ignore dozens of comments on them (which I find rude), or
3: I post them as above, or
4: I find yet another hostingsite (btw: did you post that pic on Volvoforums itself? I do use the pics elsewhere, but then it might be worth the effort putting them (and the wiperpics) on here too. Afaik this wasn't possible years ago, but maybe I just never looked into it.)

[shoebox]

Thanks for your post. Please were you able to resolve your issue with heatsinks and fan?

[R-P]

(Knock on wood) The issue has not resurfaced. It works flawlessly (that part of the car..., turbo issues, clonking issues, AC issues all still not addressed and/or fixed).