Hey John, I was wondering about you! I hope you're well. I'm back in Japan and have seriously been depressed. I really hope to get back to North America before too long.
I found a Japanese web site where this person has actually opened the ABS module for repair. I'll attach pics & translation. Note, however, that this was done on V70, but I assume it's pretty much similar to 850, so I'll attach a circuit diagram (which you may also have in your Haynes manual):
Pic-1:
Remove the star washers x 4. The cover is glued onto the housing with silicone-resin and this does not come off simply by prying.
Pic-2 & 3:
Next, remove the resin with a sharp knife/screw driver slowly, around the entire housing. There are no lock tabs, but takes quite a bit of force to remove (cut through) the resin. Do not insert the tool deeply into the housing, as this will damage SMDs. I used what is called "Mac opener (the tool in the pic)"
Pic-4:
The circuit board is coated with transparent silicon film. The opposite side is mounted onto the housing, and requires unsoldering at the connector (x30 spots) and the solenoid (x14 spots) with unsoldering tool & a suction-type solder remover. This is a major work.
Pic-5:
The circuit patterns seem little to narrow for this type of module. As you cannot see the circuit pattern from the top side, expect the job to be time-consuming. The wheel sensor patterns should be the last to inspect, but re-solder the connector socket for the wheel sensors( x8 spots). For soldering, I've used a 20W solder iron. This time I have removed the clear silicone film for re-soldering. For the silicone film removal, I used a plastic scraper and a pair of tweezers.
Pic-6:
The connector pins for wheel sensors are as follows (they are for V70 and may be different on 850. See attached circuit diagram on the next post):
LF: Pin-11 & pin-4
RF: Pin-18 & pin-3
LR: Pin-2 & pin-10
RR: Pin-1 & pin-17
*The pin configuration does seem different on 850, according to the schematic.
Pic-7& 8 & 9
It is best to re-solder all connector pins (circled in red) as they are noted for cracking. The first repair failed after 6 months, so this time I used a 60W iron and used plenty of solder.
Pic-10:
I've also re-soldered other areas to ensure correct operation.
Pic-11:
After re-soldering, clean the varnish produced by the solder, apply clear electrical circuit silicone compound and smooth it out. Leave it for 24 hours before putting the cover back on. Finally, put the cover on. Apply silicone sealant onto the mating surfaces, put the cover back on and wipe off excess compound.
Re-installation Notice:
It is tricky to reconnect the large connector, as it has locking cover. If this covered is opened too wide, inserting the connector will become difficult. The cover moves as you press on the inside of the hinge, so use a small screwdriver to press on the hinge while reconnecting.
I also did some research on 850 throughout Japanese web sites, and the ATE's ABS modules
were guaranteed to fail, due to poor manufacturing and the fact that it's suffering heat & vibration damage; one of the worst enemies to electronic devices as you know a lot better than I do. But some of them noted that the damage is usually around soldering, so you may be able to re-solder some components or test them with your DMM.
P.S: Tech has not been available for a while. I'll list you with the last thread Tech has posted.
http://www.volvoforums.com/m_56118/tm.htm
Welcome back!
Kanji, a.k.a JPN
ABS Controller Cover Removal
missing pictures......
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