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Haldex AWD Diagnosis/ Repair

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

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Blacklab467
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Haldex AWD Diagnosis/ Repair

Post by Blacklab467 » Wed Jun 17, 2020 4:11 pm

I have owned my 2003 XC 70 for about 5 years now. The AWD system doesn't work anymore and I could not recall when it stopped working or if it ever worked since I owned it. The car has 270,000 kms. on it and I would really like to get the AWD working. I've fixed everything else on the car and labour is cheap right now as I'm laid off due to Covid. I would be willing to spend up to about $700 on this car to get it working.
Could someone help me in determining what the problem is with it or point me to a link in diagnosing whether it might be the bevel gear or the Haldex pump or what. And also how much to repair either component.......or if it will cost way too much to repair and I should just forget it.
The check engine light is on as it always is, so I suspect there is a DEM code in there and maybe some others.
When I start driving in slippery conditions from a start the amber traction light comes on and I can feel something trying to happen in the Haldex so I can't help but think that there may be some life left in it but don't know where to start.
Thanks in advance for your advise.

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Re: Haldex AWD Diagnosis/ Repair

Post by jonesg » Wed Jun 17, 2020 8:40 pm

Mine leaked oil and I could hear the pump running so I pulled the fuse.
Theres a filter in a housing attached to the unit that can changed. The DEM box attached to the side can be removed with 2 allen bolts and checked or rebuilt by xemodex. the controller has 2 plug in pressure probes that trigger the control solenoid, they pull straight out to remove. It can be a bit of a project getting at the pump, depending which generation haldex you have.
On some you have to drop the prop shaft starting at the angle gear box.

I gave up with mine and pulled the fuse, all fixed.
xemodex and Oragex have good videos for servicing.


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Re: Haldex AWD Diagnosis/ Repair

Post by - Pete - » Wed Jun 17, 2020 10:17 pm

A new DEM pump will run the better part of $300, part only. You’ll also be wise to replace the filter and the special Volvo AOC oil that goes in the case as well.

Pulling the fuse is obviously not a fix, nor is it what you would do if you live in an area where inclement weather is imminent. But it can eliminate the annoyance of a light on your dash.

Personally, I’d attempt to drop the driveshaft & fix it properly. 270k k’s is a pretty good lifespan. It (driveshaft removal) can give a good fight so be prepared. On XC’s you must first free it from the bevel gear output flange. Then you can free it from the oscillation damper/input flange on the AOC/DEM/Haldex. You’ll also need to remove the 2 12mm bolts that secure the hanger bearing to the tunnel.

As an alternative, you can rebuild the DEM pump fairly inexpensively. There haven’t been a whole lot of detailed write-ups on it though. The last pump I bought was Volvo & came from Amazon for about $285 pretax iirc.

You can use the cars DIM display to inform you if your DEM is functioning or not. With the key on and engine running (in park), press and hold the “Read” button on the left stalk/turn signal. While holding that, press twice the rear fog light button. On the screen you can now see the various modules in the car. Press the read button to toggle through the modules to see their functional status. “Ready” means functional. Press the read button until you see “DEM _______”. Hopefully it’ll say “DEM ready”. If it does, your DEM may still be functional.

There is also the chance that if your DEM is still good that your bevel gear (it’s a transfer case bolted to the trans) or collar sleeve (transmits power from the trans to the bevel gear & is sandwiched between the two) could be kah-poot. Obviously if one or the other has gone sour it’ll need to be replaced.
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Blacklab467
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Re: Haldex AWD Diagnosis/ Repair

Post by Blacklab467 » Thu Jun 18, 2020 7:48 am

Thanks for this information. What is the best way to test if the bevel gear or collar sleeve is intact and working correctly? I was thinking that if I have to rebuild that AND spend money on the Haldex and associated components in the rear that it may be cost prohibitive to restore the AWD.
Also, if the traction light is coming on when accelerating on a slippery surface, and I can hear something happening in the rear diff, does that mean that the DEM and pump are sort of functional?
Thanks.

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Re: Haldex AWD Diagnosis/ Repair

Post by - Pete - » Thu Jun 18, 2020 8:00 am

It’s extremely unlikely that all 3 would fail simultaneously. My bet is on your DEM pump. The easiest way to verify if your bevel gear/collar sleeve is intact is to get the car in the air (safely), roll underneath it and grab the driveshaft. You should not be able to rotate it freely as it will be trying to turn the gears in the bevel gear and the transmission output splines as well. The driveshaft is always engaged to the bevel gear and transmission if the bevel gear and collar sleeve are intact. Typically a failed bevel gear/collar sleeve is preceded by loud clicking or grinding noises.

End of life DEM pumps can give some unsettling feelings, and be “sort of functional” as you say, in an intermittent manner. When the pump comes to life, traction is sent all of a sudden to the rear wheels & if you are under acceleration this can be felt as an abrupt jolt akin to accelerating over a garden hose/extension cord. The intermittent nature of a failing DEM pump means you can’t always use the rudimentary test I posted earlier to verify if your DEM pump is truly functional or not. But as a preliminary test it can tell you if there is connectivity there and if it is intermittent.
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Re: Haldex AWD Diagnosis/ Repair

Post by jonesg » Thu Jun 18, 2020 8:39 am

Blacklab467 wrote:
Thu Jun 18, 2020 7:48 am
Thanks for this information. What is the best way to test if the bevel gear or collar sleeve is intact and working correctly? I was thinking that if I have to rebuild that AND spend money on the Haldex and associated components in the rear that it may be cost prohibitive to restore the AWD.
Also, if the traction light is coming on when accelerating on a slippery surface, and I can hear something happening in the rear diff, does that mean that the DEM and pump are sort of functional?
Thanks.
if the bevel gear is good the prop shaft will spin, it should spin constant, the AOC system engages when needed to drive the rear end.
We had a discussion on getting the prop shaft loose from the rear coupler 3 yrs ago.
The guy finally succeeded by driving it forward with an air hammer, someone else mentioned putting 3 notches in the shaft to catch a chisel and allow enough purchase to drive the shaft forward. Helps to have a lift when swinging a hammer I'm sure.

if you DIY then your budget should be enough... helps if you have the tools.
theres a place in Taunton MA that repair the DEM for $200, I have no personal experience with them as I didn't go ahead.

my volvo was a daily driver, it was difficult, retired now so I might take another look, I still have the haldex fluid and filter.
I'll watch how you progress.

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Re: Haldex AWD Diagnosis/ Repair

Post by Blacklab467 » Mon Jun 22, 2020 11:38 am

Thanks everyone, so to confirm, If I jack the front wheels up and spin the tires, the driveshaft should spin also. Is this the best rudimentary test of the Angle gear/ collar sleeve?
Also, the procedure for checking the modules on the DIM doesn't seem to work on my car! I started it and left it in park, held the "read" button and pushed the rear defog button twice, nothing happened, I tried it a few times. DIM was rebuilt by Zemodex about 3 years ago.

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Re: Haldex AWD Diagnosis/ Repair

Post by - Pete - » Mon Jun 22, 2020 1:23 pm

Rear FOG light button, not defog.

I’d get the entire car off the ground. If your bevel gear is good and collar sleeve/BG input splines are intact the driveshaft should not rotate freely. If you can rotate the driveshaft your front tires should also be spinning.
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Blacklab467
2001 V70XC 146k
2004 V70 AWD 141k
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2004 XC70 287k
2006 XC70 155k Sold

Blacklab467
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Re: Haldex AWD Diagnosis/ Repair

Post by Blacklab467 » Fri Jun 26, 2020 3:40 pm

Ok, so it appears that the bevel gear is fine. I got all fours off the ground and confirmed that the driveshaft cannot be rotated freely. Also, back wheels rotate freely and independent of each other with no movement of the driveshaft. I then started the engine and put the car in drive and the back wheels and driveshaft turn with engine acceleration, only not very fast, certainly not as fast as the front.
Would this suggest that there may be some life back there? Could the pump be weak or low on fluid? There doesn't seem to be any leakage or corrosion on the DEM.
Also checked the DTC's and I do have a DEM code set in there.
What next?

jonesg
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Re: Haldex AWD Diagnosis/ Repair

Post by jonesg » Fri Jun 26, 2020 5:53 pm

Blacklab467 wrote:
Fri Jun 26, 2020 3:40 pm
Ok, so it appears that the bevel gear is fine. I got all fours off the ground and confirmed that the driveshaft cannot be rotated freely. Also, back wheels rotate freely and independent of each other with no movement of the driveshaft. I then started the engine and put the car in drive and the back wheels and driveshaft turn with engine acceleration, only not very fast, certainly not as fast as the front.
Would this suggest that there may be some life back there? Could the pump be weak or low on fluid? There doesn't seem to be any leakage or corrosion on the DEM.
Also checked the DTC's and I do have a DEM code set in there.
What next?
The problem moved from the front to the back.
Check the fuse for the haldex in the rear compartment.
theres a 2 pin connector at the pump, disconnect ,
check pump by measuring resistance of the two pins, should be around 2ohms.If its higher its time to repair.
Thats all I know, I decided to just leave the fuse out and forgetaboutit.

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