Powerseat and aircon intermittent

[Mr Bagshaw]

Hi, I have a problem with my 2002 xc70. The powerseat and aircon are intermittent. I can make them work by taking out fuse 24 and putting it back in but this only fixes the problem for a short time. The fuse does not blow and the instrument cluster does not have a problem and works as it should. Any thoughts and suggestions greatly appreciated.

[billr99]

I would suggest a VIDA scan to see if it picks up anything that might connect the two systems for this. Each system is controlled by a different CPU which might say that it isn't those but might point to some common power feed problem or similar.

Just as an example, over the last year and on both my P2s I had a "power system failure" CEL come up, pointing I thought to either the batteries (both were oldish) or the alternator (both original). In each case, VIDA didn't help all that much so in both cars, the alternators and batteries were replaced with no joy ultimately. In both cases, the cars eventually got to the point of a failed to start, wherein VIDA finally indicated a failed fuel pump control module (PFM). Seemingly unrelated failure and the only thing I can figure with it was that the circuit boards in both failed PFMs were heavily corroded with that corrosion somehow producing the "power system" message.

So I guess I'm telling you is to get a VIDA scan but be prepared to do a bit of digging to find out the ultimate cause.

Good Luck,

Bill

[Mr Bagshaw]

Thanks Bill, much appreciated. Yes I was afraid that there would be some pretty serious digging to do. Can you recommend any VIDA scanners for the home tinkerer that doesn't entail selling my entire family?

[billr99]

Thanks Bill, much appreciated. Yes I was afraid that there would be some pretty serious digging to do. Can you recommend any VIDA scanners for the home tinkerer that doesn't entail selling my entire family?

Not really. I'm an old IT guy so I just used an old Dell laptop I had laying around and made a dedicated VIDA scanner out of it. VIDA isn't hard to do if you start from scratch and put nothing on the laptop otherwise. I don't even allow it to hook to my network or do any updates above the basic install of Win 7. So if you can do that much, its not a bad deal. As far as the DiCE interface, I got mine from China years ago so I'm not sure what the new version are like. Perhaps someone who reads this can add their two cents on that subject.

Cheers,

Bill

[BillAileo]

I went the same route as Bill and everything went great for quite a long time until I absent mindedly updated the laptop. Do not do that unless you want to revisit the entire process.

[pbierre]

Have you tried cold-rebooting the entire car system? This works with home computers that slide into a glitch, and it works with cars too where the problem is not hardware.

Turn car off at least 5 minutes.

Disconnect battery negative terminal cable. This kills power to everything except the security alarm (which has a small battery).

Put the ignition key in position "II".

Reconnect the battery, taking care to keep a solid contact while tightening bolt.

Leave ignition in "II" position for 2 minutes - time enough for all modules to reload sw from flash and reboot.

Car now ready to startup and test. Reset clock.

[Mr Bagshaw]

Thanks everyone. Will have a play with it at the weekend.

[Mr Bagshaw]

Just tried the cold reboot but alas the seat and aircon will only work for a bit. Its odd, if I turn ignition off, remove fuse 24, turn on ignition and then off again replace fuse all works again for a while.
Got to say and this may not be the forum to say it but this sort of problem does make my 1984 Mercedes w123 wagon and my 84 Range Rover more appealing.

[billr99]

Just tried the cold reboot but alas the seat and aircon will only work for a bit. Its odd, if I turn ignition off, remove fuse 24, turn on ignition and then off again replace fuse all works again for a while.
Got to say and this may not be the forum to say it but this sort of problem does make my 1984 Mercedes w123 wagon and my 84 Range Rover more appealing.

Not to worry. There are days that I wish I was back in my '93 RR LWB instead of having to delve into the brains of either of my '05 Volvos. Might have gotten crap mileage but it started and went in all weather including -40C.

Cheers,

Bill

[Xfingers]

Are you the only one who drives the car? Hopefully you can get the seat into a position that's comfortable and leave it there.

I'm not sure why your aircon is intermittent. Some people have had mechanical problems with the clutch on the pulley being worn and fixed it with the "bread clip" method. You can search on it for more info but you seem to suggest it's an electrical problem.

When my 02 was on the road, the DS power window worked intermittently. I could always get it to work if I turned the engine off but left the key in position 2. Never got around to cleaning the switch and electrical connections.