ABS module not communicating

[0x00]

2001 V70 X/C
Lost the auto trans coming down from the high country.
Limped it around a while until it wouldn't move. Barely got it up the drive and into shop. Pushed it onto lift with lawn tractor.
Removed trans. Rebuilt trans. Reinstalled.
Battery was unhooked for at least a month or two. I periodically charged it up even unhooked.
Started car and instant ABS brake fail stop safely. I let it idle to burp cooling and circulate new steering oil and to adjust trans oil level.
Hooked up scanner to see what sensor I left unplugged, but instead it said 'module not communicating.'
I unhooked, shorted leads, reconnected battery in the magic order but same thing. Trans module reported no codes (If I recall, I could be wrong) so I think that one is talking. Everything else seems working (didn't try radio) windows, hvac.....didn't try sunroof.....

Maybe ABS module just decided to die after no outside power for a couple months?

I didn't try wiggling the plug to clean contacts yet (Is plug under front next to airbox?). Car has been indoors the whole time on the rack.

Don't bother saying it, I know already that you are all correct:
I should have found a manual trans.
I should have done an LS swap.
I should have walked away from the poorly designed, disposable car. There's a reason no one fixes them. Maybe I needed to prove that I COULD?

[jonesg]

on some years a no ABS situation triggers a no shift or delayed shift condition .
was that the original problem ?

[deano1]

Brake module not communicating really not the end of the world, but when your wife does that? Then you should worry!
So i just went through this so I can say that if you have access to scrap yards then things just got a whole lot better, but if not just use online sources for your needs. Erie VolVo come to mind.
Hears the deal, Find another module with exact part numbers that are on your original.
So mine was 8671224. It's that number Just under The Ate controller and under that it says "brake control module".
Plug and play baby!
Hopefully that helps.
Cheers

[0x00]

Thank you both!
I think this is how it played out:
Trans is not serviceable and I got it up to about 200K miles. It did get oil around 160K when I got the car.
It started going into limp mode. It would reset with key off/on. It slowly got worse. It sort of worked better in manual mode. I let wife drive it once and after that it wouldn't move (no concept of higher than normal revs means slipping, I got away with it by knowing that and doing anything else but letting it slip).
Inside of trans looked great. no hot steels and all frictions I could read the writing. Known issue, front bushing on rear? (smaller) planet walked out of bore. I think this caused loss of pressure hence no more go. I went back with a one-piece in the planet, DuraBond everywhere else, Raybestos frictions, Trans Tec kit (included the oversized seal for bevel gear splined sleeve), LocTite 638 reinforcing the housing-to-transfer gear wear area, reused steels, had Branting in Arvada rebuild the torque converter, bolted on new GM valve body with one valve swapped to make it 'volvo/nissan compatible,' and, of course, the filter that's only accessible by disassembling the box. So.....that was the ante to sit at the table. Then we: new splined sleeve into bevel gear, reseal bevel gear, reseal bevel gear sleeve (yep, there's one in there, too), new bevel gear vent, new front engine mount (tension pulls it apart, rear won't do this) new right side engine mount, new round bushing for the top torque (seems like this plastic and rubber part will last all of a few weeks, assuming the car drives again). New grommets for the shaft support and cat support, gasket and locknuts at turbo. I have to go final torque all the front end stuff and some little parts before I can drive it. And, just in case anyone is thinking about this, there will probably be 'adaptations required' for the new trans.

[0x00]

Hey Deano1:
Did you open the bad module? Still have it? Were the symptoms simply 'no communication?'
I once repaired a Porsche transfer case control module. Dealer and TSB said 'must replace both motor and module' which was a lot more $ than a motor only. I ordered a motor and opened the old module and found two 'current sensing MOSFET with built in Hall effect sensor' burned up. Some Russian eBay guy in LA had these obsolete parts listed so I put them in and away I went. Was able to rework board with no trace damage and minimal 'burn evidence.'

I was wondering if an electrolytic cap in the volvo abs module was able to last the 20+ years with power always applied and my disconnecting the battery for months let some failure mechanism 'grow' in the cap until it rendered the module (or it's comm. driver) inop. Google wasn't much help trying to learn if DC filter/decoupling caps can 'fail after long disconnection of power.' I'd love to see photos of the module guts or schematic but I don't think I'll find any.

Ill start looking for secondhand module.....

[deano1]

I didn't bother to open because with no formal electronics knowledge I'd really have no clue what to look for.
I'm still trying to figure out why my UEM is not communicating with CEM.
I have another UEM with same part number but I don't think I can just plug in another UEM with all key for info to deal with? Maybe worth a try?
This all started after I sent CEM out for rebuild at Xemodex.
Now the car completely shuts down after being turned off for 5-10 minutes and I lose the key fob fucntions/interior greeting lights?
But turn the ignition key to position 2 then back to position 1 then again to position 2 and everything powers up and all functions are active once again.
Been working with Xemodex customer service and doing a lot of searching of the webs but I'm still at a loss for why this situation persists when all was fine before the transfer?
Cheers

[0x00]

So, I went to look at the inop abs module and lo-and-behold it was a rather clean looking XemodeX reman. I sent them the serial number and requested history on the unit and never heard anything at all from them. Crickets. I removed the module and pried it open. It was very difficult to open without cutting it like everyone else does. If I had to do it again, I would cut it, I think, especially if I was on the clock for a customer's car. I found nothing amiss inside. It was evident that the small pins at the connector were reworked. There was flux not cleaned off. I cleaned it an tested pin-component traces and didn't find any problems. I gave it a careful look over then hooked it up while open and it worked. So I glued the top back on, reinstalled and reset codes. Car is still complaining about a brake light switch or a pedal position sensor but I'll dig into that later. At this point all I can conclude is that I wiggled the wires to fix. There were two or three events of removing the two 30A fuses and replacing them but I would not expect that to be different than the battery discon/recon events.

[0x00]

Hey Deano1:
It sounds like you ONLY messed with the CEM and had it reworked? Then, the upper module stopped talking but everything else works? No work at all on the rear view mirror or stuff topsides? Grounding? new windshield?

the below topic, post#3 discusses resetting the uem, but if it can't communicate at all I doubt it will help. You might try the key in position II battery connection nonsense; I am still not sure how they came to that.

https://www.volvoforums.org.uk/showthread.php?t=40932

I am going to try and see your posts in case you started a topic.

[jonesg]

" You might try the key in position II battery connection nonsense; I am still not sure how they came to that."

I think is ensures a soft boot up, prevents an airbag going off from any v spike.

[vtl]

Read the codes with DiCE/VIDA. It is a high chance you have a brake pedal position sensor gone wild, the one on the booster. The car then limps into 4th gear with torque converter unlocked.

https://www.fcpeuro.com/products/volvo- ... e-30742306