Hello all,

I have not had good luck with the AWD on these cars. The first car we bought (used) was a 2004. I didn't test the AWD before we bought it and found out after the purchase the engagement gear (sliding coupler?) was stripped on the inside and the outside. That was not a cheap repair.

On the second car we bought (current one) we didn't have a chance to have the car tested before purchase and it too did not have the AWD working. This time is was a plugged hydraulic line. With that fixed we had AWD, however I am not happy with it.

My understanding is that one or both of the rear wheels are engaged when there is a difference in speed detected between them and the front wheels. When this happens a hydraulic pump disengages a clutch and power is sent to the rear wheels. What I have found is that sometimes with the front wheel(s) spinning the rear wheels don't engage at all and I am stuck, causing me to reverse out of my position. Other times I'll get stuck and with the front wheel(s) spinning the rear wheel(s) won't engage for 5 to 10 seconds or longer and when they do they come on with a bang (not gradually engaged and it is very unnerving). The cannot be good for the sliding gear set. Other times as soon as the car is stuck the rear wheel(s) engage immediately and the car starts moving again.

I do not know how this system works, but it seems to me that the speed difference between front and rear wheels is only sensed off one of the front wheels. If it happens that the other front wheel is spinning then the AWD does not engage. When the un-sensed wheel is spinning and gradually finds traction and then with the open differential it causes the sensed wheel to spin, then the rear wheels are engaged. I proposed that this is the delayed engagement scenario described above. However, if the wheel that is sensed is the one spinning then the rear wheels are engaged immediately.

Am I understanding the system correctly or do we have a problem with our vehicle?

TIA,
Blane

 

Yes, there is a problem with the haldex system. It should provide power to the rear wheels when the fronts spin faster than the rears.

 

Thank you for your reply. Looks like I need to educate myself on the Haldex system to see what my next step will be.

Blane

 

A good first step would be a scan with a compatible scan tool. xemodex has a diagnostic flow chart that might help.

https://xemodex.com/us/diagnostic-flow-charts/

 

hoonk,

This is great information. Thank you very much for posting. I took a quick look at one of the flow charts and if the others are similar it may be beyond my skill level. Nonetheless I'll dig a bit deeper to see how they can be of value to me.

Thanks again,
Blane