Haldex woes

IVIUSTANG · Apr 26, 2019

Hey gang!

I had some pretty frustrating issues with my 2008 S80 V8 on a recent roadtrip; all of these issues started at the exact same moment on the highway. I lost adaptive cruise, DSTC, AWD and collision warning system. I did a Vida scan and came up with the following relevant codes:

BCM-U013600 Lost communication with differential module - rear
FSM-U041568 Invalid data received from brake control module - Algorithm based failures

I did some of the fault tracing steps and found the 10 Amp fuse for the DEM in the trunk was blown, I then did a test of the Haldex pump per XeModeX directions on their website(disconnect pump and ran 12v to it to verify operation) The pump ran kind of noisy but fairly smooth for about 10 seconds and then stopped completely and it started fizzling and smoking, I quickly disconnected the jumpers from the pump. If my pump wasn't bad before it certainly is now.

I have a couple of questions based on this.
1. Is it common for these pumps to fail in this manner(ie. start drawing too much power, blowing DEM fuse, then during testing with non fused power to burnout?)
2. What are the odds all of my systems failures and Vida codes are connected to my issues with the DEM/pump?

Any other helpful insight also highly appreciated. I am very worried about throwing a new Haldex pump at this car and also having to deal with additional problems that may still exist.

Thanks,
Jesse

IVIUSTANG · Apr 26, 2019

Also, would it be a bad idea to leave the pump unplugged and install a new DEM fuse; would this be a valid and safe test to see if the DEM coming back online would resolve the other issues?

Thanks!

Seamus · Apr 27, 2019

I would replace the pump and the fuse and see it it resolves the issue. I would guess the pump made the fuse blow and the blown fuse was the cause of the lost communication with the dem.

Sent from my iPhone using Tapatalk

IVIUSTANG · May 10, 2019

Just as an update to my original post, I replaced the Haldex pump, installed new filter and fluid put a new 10A fuse in, cleared all my codes in Vida and now everything is working perfectly. So it does appear the DEM being offline does disable DSTC, cruise, collision warning etc and causes a lot of warning messages on dash.

As an aside, I will say after having done AWD pumps on both a P1 S40 and P2 Xc70 that the P3 S80 is a bit easier to change the pump as the propshaft can be disconnected from the Haldex unit without lowering the exhaust. Surprisingly my old AOC fluid was pristine and there was no particle buildup on pump pickup screen, so an overloaded pump was not the cause of the pump failure as is commonly the case.

I also changed the Front and rear differential fluids with synthetic 75w90 gear oil at the same time, those fluids were nasty after 221,000KM on original fluid.

Take care!

Haldex woes

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