Power service urgent

xallenx · Post by **xallenx** » 21 Jan 2012, 19:25

My wife said that the battery light came on and on the message center it said "Power service urgent". I started the car and no message was stored. I turned everything on to see if the message would come back but nothing. Checked voltage while the car was running with Heat, radio, all lights on and it read 13.5V. Do I need to replace the alternator? Should I go ahead and do this or wait until the message comes back?

Post by **gshadow325** » 22 Jan 2012, 05:50

its dying...will need a flatbed soon if this is not addressed soon, dont think your xc90 plays with you like that...thats your first chance, next time she'll not be so forgiving. LOL

Post by **jimmy57** » 22 Jan 2012, 09:46

2005 and later have an externally controlled voltage regulator. Don't throw unneeded money at it before getting it checked.
13.5 volts idling with lots of stuff on is fine. WHat is the voltage if the engine is at 2000 RPM with all the items on?
The voltage output will vary a lot of the newer system. CEM monitors a few things and can do cyclic high voltage with periods of lower than expected voltage to if monitored parameters indicate a need for sulphation reduction charge cycle.
An alternator with the Alternator Control Module (new name for the voltage regulator that communicates with CEM or ECM to receive and send signals about charging level) instead of a conventional voltage regulator will be more.
The alternator has a one way clutch in the pulley and those can fail and let alternator slip but usually it is noisey when you raise engine speed right after starting it. It is a screech but not like a slipping belt screech.

xallenx · Post by **xallenx** » 22 Jan 2012, 15:38

Voltage stayed at 13.6 while the engine was at 2000RPM. This is with the radio balsting, foglights on, headlights, heater on full blast with the interior lights on.

Post by **jimmy57** » 22 Jan 2012, 16:50

That is probably right on target for that system.
Make sure the wire connections on alternator are secure. Since yours is a Bosch fuel system engine the CEM is what is wired to communicate with the ACM/Alternator.

xallenx · Post by **xallenx** » 22 Jan 2012, 18:18

The wires are secured. Plan on driving it to work tom. and see how it goes. I got my AAA card ready just in case..ha!

xallenx · Post by **xallenx** » 26 Jan 2012, 18:28

UPDATE: Well, so far the xc has been running without the Power service urgent light coming on. Weird!