2008 XC70 going into limp mode and various electrical glitches

[IVIUSTANG]

Hi guys!

Posting this for a friend who just bought a new to him 2008 XC60 3.2l

2008 XC70 NA 3.2L AWD. 218,000 kms.
This problem started happening approx 1 month ago.
About every day I drive the car, the following cycle occurs: I drive along like normal, and after a few 90 degree left turns I have to make on my work commute, I notice my speedometer flashing up and down (4 or 5 times) between 0kph and whatever speed the car is travelling at, during the left turn. Usually one left turn later, after the speedometer waving up and down, I get a few driver messages all at once - Brake Failure Stop Safely, DTSC failure service required, and Parking Brake service required. As soon as this happens I experience about a 40% drop in power, especially noticeable when starting off from a stop.
A few other things of note:
- The gear indicator on the instrument cluster shows a dash (-) instead of D for drive, etc.
- When shutting the engine off, occasionally the 'start' button requires multiple presses before it will shut down.
- After the engine turns off, occasionally the key itself requires multiple presses into the ignition before it will release the key.
-this also happened on the highway a few times where the car completely stalled then restarted again while it was coasting, if given too much gas it would stall out
- I recently replaced both front sway bar links because the original ones had broken off from the top end where they were bolted to the hub assembly. The passenger side one was fully broken off and not connected by any material at the top, driver's side was still 50% attached at the top. One theory of mine is that the loose link had dragged a speed sensor wire out of its stable connection but upon inspection seems intact.
-The battery was replaced as it had loose posts and was leaking
- The negative battery cable is partly corroded and I am awaiting a replacement from Amazon.
- This is the only electrical issue I have. Everything inside the car works - stereo, A/C, windows, etc.

I have personally read the codes with VIDA and there are WAY to many codes for me to make sense of; I will try and find the screenshot I have of all the codes and add it to this post tomorrow. I did take a look at this XC before he bought it and I can confirm none of these codes were pre-existing when he bought it.

If you have had a similar issue with your p3 xc70 I'd be interested to know how you fixed it or what you determined to be the cause. I suspect there is a bad speed sensor somewhere or a short causing the chain reaction of symptoms but any insight would be greatly appreciated.

Thanks a ton!

[pbierre]

It seems that the car suffered 12V electrical brownouts/dropouts with the old battery. There may be codes sitting in memory from those incidents that just need to be cleared using VIDA. Clear your modules of all codes, and see which ones return.

As far as the speedometer instability and brake-service messages, you could have a bum wheel sensor. VIDA can see into ABS module for any wheel sensor codes.

[tancookbelle]

I have 2009 XC70 3.2 with 357,000 km and batteries seem to only last three to four years before they need to be replaced. The first time this happened about 2012 I would get the "parking brake service required" message when starting the car and occasionally on stopping the fob would take a couple of tries to release. I replaced the battery but found the car still seemed to start hard. So I started by first removing the battery ground to body wire at both ends and cleaning both ends. I then removed the air cleaner to access a group of ground wire connections. The main ground wire to the engine block was removed and cleaned block. There are about six smaller ground wires near the main ground including ECM, ABS, etc which I removed and cleaned. I also was not happy with overall ground arrangement from battery to body and then body to engine so I installed a ground wire between the two body points. Once the left side grounds under air cleaner were cleaned and additional ground wire installed, I no longer have starting issues, fob works great and the "parking brake service required" has not returned even though I have had to replace the battery two more times.

I would check the ground connections under air cleaner before chasing codes.