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Haldex AWD Diagnosis/ Repair

Help, Advice, Owners' Discussion and DIY Tutorials on Volvo's stylish, distinctive "P2" platform cars.

2001 - 2007 V70
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- Pete -
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- Pete -

Re: Haldex AWD Diagnosis/ Repair

Post by - Pete - » Fri Jun 26, 2020 10:40 pm

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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Blacklab467

Re: Haldex AWD Diagnosis/ Repair

Post by Blacklab467 » 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!

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