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View Full Version : strange electrical problems; please help diagnose



roadhog
10-17-2013, 11:00 PM
Ok, this is a 2004 xc70, approx 81k miles. I'm original owner.

No history of electrical issues, but it is on the original battery (I know I know, it's too old).

Today I got in the car after work to come home. As I approached I noticed that the key fob wouldn't unlock the doors, then I noticed other quirks. The car did start and runs fine except takes longer than normal to "spool up" in rpm's from a stop to begin moving. I drove it home, but all kinds of electrical things aren't working. I checked fuses and haven't found any bad ones. Here is a list of things that do and don't work; not comprehensive I'm sure because so many things don't work.

Doesn't Work: high beams, rear automatic windows on both sides, turn signals, entire instrument panel (nether the lights in the panel nor the actual functionality..i.e. no speedo, no tach, etc...the instrument panel is completely black except for the check engine light which remains on), no controls on the steering wheel work, reverse lights, sun roof, automatic lock button

Works: Engine, ignition (it's driveable), low beams, wipers, automatic windows for driver and passenger only, tail lights, brake lights, radio and most things in the center console along with it.

Any thoughts? Thanks for the time!

guyeye
10-18-2013, 06:57 AM
Rule out that battery (sounds like you have a gut feeling about it anyway). At least have it tested. A failing battery is the root cause of many an unexplainable electrical gremlin in these cars.

howardc64
10-18-2013, 08:51 AM
I had weird electrical gremlins once where half of the car's electrical systems didn't work. Disconnect and reconnect the battery (reset the electronics) worked for me and it never occurred again. If you do this, please read up on how to do it properly to avoid damaging the electronics

http://howardsvolvos.webs.com/miscissues.htm#207347288

May need to lock and unlock door afterwards to resync a couple of electronic subsystems.

roadhog
10-18-2013, 11:29 AM
Thanks. Guy, you are right about my gut. I will never understand electronics in cars, but in the past (different car) I have been surprised about the impact of a failed battery as well. I'll pick up a new battery and install it later today and hope for the best. I'll report back.

roadhog
10-19-2013, 12:01 AM
So I replaced the battery and shazaaam! Everything works normally again. I'm an idiot. I should have known better, particularly with the known age of the battery. The symptoms just seemed so weird, but I've learned this lesson before with another car. Failed batteries cause weird things.

On the bright side, making the original volvo battery last for 9 yrs and 10 months of driving is sort of impressive, no? :)

guyeye
10-19-2013, 06:31 AM
Fan-tastic! Love the easy fixes.