Haldex AWD Diagnosis/ Repair

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2001 - 2007 V70
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- Pete -
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Re: Haldex AWD Diagnosis/ Repair

Post by - Pete - »

That’s great news for your bevel gear & collar sleeve. Did you observe both rear tires? One could have been spinning far faster than the other seeing as there is a differential between the two.

My best guess remains that there is definitely an issue in the AOC/DEM/pump vicinity, now confirmed by the rudimentary DIM readout you did. I’m sticking with my original prediction that your pump has gotten flakey, but obviously I could be wrong.

The absence of oil indicates that there isn’t a profuse leak, so it’s likely not a fluid level issue. All fluids degrade with age, so yes, new fluid could help. Possibly only for a short while, the longevity of improved function remains to be seen. As I’m sure you can now see, the filter can only be replaced if the driveshaft is out of your way. To me, a fluid replacement alone will only be marginally beneficial unless supplemented with a filter replacement as well. Put it this way, if you end up replacing the DEM pump, you will absolutely be replacing the filter and AOC oil as well.

If you accelerate on gravel with some gusto can you feel the back end pushing? It’s pretty evident when your RWD has truly quit.

On the car I believe I mentioned earlier, I did do a AOC oil & filter change prior to changing out the DEM pump and Lo and behold, I did see some regained function of my RWD. Alas, this was short lived and my pump ended up failing completely in the end. In my book (for my cars) it is unacceptable to carry on as FWD. I do understand that fiscal & mechanical ability/space limitations are a major factor for some.
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Blacklab467
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Post by Blacklab467 »

Ok, the fuse is good, I checked yesterday. I'll check the pump resistance this morning as well as the haldex fluid level.
I find it interesting that there is a DEM code set in the DTC, yet the Haldex "kinda" still tries to work on icey roads, just not very well. I'm wondering if I should just change the filter and fluid and take the pump apart and clean it up and cross my fingers. I think a DEM repair is about $6-700 bucks at Zemodex.
Not really looking forward to removing the driveshaft! That looks like a pretty nasty job!
2003 XC 70, 2007 Duramax LBZ.

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Post by Blacklab467 »

Ok, I decided to take the plunge and service the Haldex after confirming that the bevel gear/ collar sleeve is in good shape. I just ordered the filter and fluid from IPD and will take the pump apart and clean and service it at the same time as the fluid and filter go in. I've decided that I will bite the bullet and pay for the DEM to be checked and rebuilt if required from Zemodex, I live in a part of Canada where it is necessary to have AWD and this is my ski machine and have already fixed everything else that was required.
My question is: What is the best most straightforward method to remove the driveshaft with the least trouble. I have read numerous techniques and problems encountered and know that many of you have done this job several times. I just want the least troubles when I tackle this sometime next week. Is it necessary to drop the exhaust, should I soak any bolts in WD40 now? Any other tips?
I am also going to print the Zemodex flowchart and go through it to find out if theres anything else that might help me determine why my AWD doesn't work anymore.
Thanks in advance!
2003 XC 70, 2007 Duramax LBZ.

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Post by jonesg »

Blacklab467 wrote: Sat Jun 27, 2020 7:52 am Ok, the fuse is good, I checked yesterday. I'll check the pump resistance this morning as well as the haldex fluid level.
I find it interesting that there is a DEM code set in the DTC, yet the Haldex "kinda" still tries to work on icey roads, just not very well. I'm wondering if I should just change the filter and fluid and take the pump apart and clean it up and cross my fingers. I think a DEM repair is about $6-700 bucks at Zemodex.
Not really looking forward to removing the driveshaft! That looks like a pretty nasty job!
there are cheaper alternatives , a company in Taunton Ma repairs DEM cheap.
but if the pump is the cause a new DEM repair will burn out again due to pump overloading it.

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Post by - Pete - »

I can write something up this evening (hopefully I remember!). First, though, did you see if the existing pump responds to voltage? It may be tough for an untrained ear to tell with the engine running, but you can do it that way. Also if you unhook the 2-conductor plug you can apply 12v right at the plug. The pump should spin rapidly and sound strong. I don’t have a good example of what a strong pump sounds like.

By the way, were you able to decipher what the DEM code was in relation to? This would be important in helping you to know what parts will likely need to be replaced. There is a board inside the DEM heptagonal shaped box & others have written about the possibility for water ingress and sand to be found in there. I do believe this is a pretty rare occurrence though. Seeing as the pump motor is of the brushed variety I still feel that it is the most likely culprit.
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Post by Blacklab467 »

I was just looking at the Zemodex diagnostic flow chart and was going to check the pump this morning to see if there is any life in there. I just checked the rudimentary DTC on the dashboard and found that there is a DEM SET but don't know specifically what the code(s) are.
My thoughts were that I would start by removing the driveshaft and replacing the filter and fluid when it arrives in the mail next week, and if I can see that the pump turns with 12V applied, I would disassemble and clean and lubricate it and then test the AWD operation. I will also check the physical condition of the DEM and related parts. If the AWD still doesn't work I would then send it in for repair.
Does this sound like a reasonable course of action? I'm trying to stay on a sensible budget for restoring the AWD.
2003 XC 70, 2007 Duramax LBZ.

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Post by - Pete - »

Perhaps before diving in and sending bits to Xemodex, it may behoove you to seek out someone locally who can scan your P2 with ViDA. Maybe a thread here & check in on the Facebook pages up in your area, you’d be surprised what fellow Volvo folk will do for others. Or someone who has a higher end scanner could possibly access DEM codes.

Most of the time you’ll be looking at a DEM-0006 or DEM-0007. 0006 is usually the pump, 0007 is usually a temp/oil psi sensor.

I think your approach is fine, but don’t be disappointed if you end up needing a pump. If that ends up being the case, you’re looking at $350-400 in parts. Pump runs $280ish , filter $30ish, AOC oil $30ish (all pretax USD estimates).

For driveshaft removal I’d definitely encourage you to continue reading up on the many trials people have had, namely in areas where salt is used in winter.
  • With car in the air, remove the 6 bolts holding the front CVJ (CV joint) to the output flange on the rear of the bevel gear. Best done with an impact and 2-3 wobble end extensions (think of an arch). You’ll need either M6 or M8 Allen’s 3/8” drive.
  • Remove driveshaft hanger bearing 12mm bolts X2.
  • Use a sacrificial bolt inserted through 1 of the 2 non-threaded holes on the front face of the output flange to “push” the driveshaft CVJ rearward out of the flange. There should be 8 holes on the backside of both your flanges, 6 are threaded, 2 are not. I’ve always been able to get these to pop loose with a pry bar & sacrificial bolt. Remember to be careful (especially!) with the front CVJ. It’s rubber boot (which keeps the grease from flinging all over your tunnel & downpipe) can be very fragile. The entire CVJ is replaceable & includes a new rubber boot but try to avoid destroying the one that is there if it isn’t already torn or cracked.
  • Repeat steps for front CVJ removal on the rear CVJ for removal from oscillation damper on AOC. Be very careful not to damage the plastic connectors (and also the wires) on the DEM. If you have an air hammer you can use it to drive the CVJ forward out of the oscillation damper.
3EBA9DDA-9F1C-43E4-B0DC-D679FEAC4906.png
  • Next remove oscillation damper from AOC. You’ll need an impact & a 24mm socket. Then tap the oscillation damper forward with a mallet & drift.
  • Unclip both electrical connectors. These become very brittle with age & the locking tabs are easy to break if you don’t pay attention to how they come undone. When releasing the connector, press down on the connector, towards the DEM, to relieve pressure on the connector tab. Insert a small flat-blade screwdriver under the connector tab and gently rotate the screwdriver until the tab is unlocked. See photo. Then, gently push up on the connector.
81CBA7A0-A78A-4C5C-909B-31FF542AB709.jpeg
81CBA7A0-A78A-4C5C-909B-31FF542AB709.jpeg (141.78 KiB) Viewed 250 times
  • Remove 2 Allen screws from pump, remove 2 Allen screws from filter. Remove filter and pump and filler plug and let AOC oil drain (measure how much comes out).
  • Replace filter and updated “finned” cover
  • Clean screen on pump, other than this and a light cleaning with WD-40 there’s not much else to do, unless you want to rebuild the pump.
  • Reinstall or replace pump. Plug both connectors back in. Be sure to blow compressed air around the plugs/receptacles as tiny stones can rest in the crevice & prevent you from fully getting your plugs clicked back in.
  • Grease up both flanges, maybe a couple squirts of grease in the pin-holes of either CVJ, then reassemble. Might want to use some thread locker on the 12 CVJ bolts also; I’ve had them loosen up after being out.
2001 V70XC 167k
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Blacklab467
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Post by Blacklab467 »

Thanks for the great information! I will keep the forum apprised of my progress and include some pictures. Also will try and find someone in my city that may be able to help with getting codes off of my car.
Do you think it may be possible to service/repair the pump by disassembling, cleaning, and lubricating the bearings, and then bench testing it? That was my plan to try first when I go in and change the fluid and filter. In my experience with other electrical motors they can usually be restored to good function with cleaning up the armature provided brushes and components are present and serviceable.
2003 XC 70, 2007 Duramax LBZ.

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Post by - Pete - »

If you’re going to take the pump apart you may as well have the parts on hand to rebuild it. I haven’t rebuilt a pump yet, but I have all my replacement parts ready on the shelf. I will post the link when I find it.

https://www.ebay.com/itm/323454791943

This seller ships quickly, very quickly.
2001 V70XC 167k
2004 V70 AWD 147k
2004 V70R M66 146k
2004 XC70 299k
2006 XC70 155k Sold

Blacklab467
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Post by Blacklab467 »

Ok so I got under the car and looked at the Haldex, looks pretty good, not much evidence of leakage. I then disconnected the pump and put 12 volts to it and a ground on the other terminal and there is no life in it at all. I wonder if there's any point in rebuilding it or it's probably in need of replacement. I don't know if I can afford a new pump if the DEM is not functioning and will need to be serviced.
I also took off the pan and looked at the bevel gear. It seems like it hasn't been leaking either and the fluid is just below the plug so thats good. I gave the driveshaft a turn, it will not turn without moving the front wheels so that's also good. It does turn maybe 5-10 degrees before it hits resistance when I turn it back and forth, I assume the resistance is the splines on the collar sleeve. Does this sound like too much movement?
Should I perhaps remove the bevel gear and give it and the sleeve a good inspection and oil change? It actually looks pretty easy to remove.
2003 XC 70, 2007 Duramax LBZ.

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