When I stop or sit in neutral my 2000 Volvo S80 idle goes up and down, how can I fix this?

Glenn Smart

• 845 Answers
• Posted on Sep 17, 2008

SOURCE: 1999 Volvo S80 will not hold a charge

Tricky ... Was the alternator replaced with a 2nd hand one or a new one?

A defective alternator can allow the battery to discharge within a few minutes (the diodes in the rear of the alternator can burn out and cause the problem. The diode pack can be replaced). When this happens recharging the battery only replaces the power in the battery - which drains straight back to earth via the alternator, flattening the battery again - often within a couple of minutes or less.

Does the battery lose its charge when the car is standing or just when the engine is fired up?
If the battery loses its charge overnight, try disconnecting the wiring from the rear of the alternator (also look at the electrical connector that fits into the back of the alternator - look for melting/burning marks which suggest something may be amiss inside the alternator).

Let the car stand overnight with the alternator wires disconnected. Will it start up ok and drive (with the alternator wires still disconnected) the next morning?

You could also try just disconnecting the alternator wires, firing up the car and then driving it -
If the car drives ok without dying out and gets further down the street than it usually does, then it probably is the alternator at fault. The car should drive until the battery drains and has insufficient power to trigger the ignition. You certainly would get further down the street with a charged battery and disconnected alternator than you currently do.

It does sound as though you've had an alternator fault to begin with. If it has been replaced with a 2nd hand unit that unit may also be faulty. Rather than replace parts in desperation, visit an auto electrician's - within a few minutes they will be able to test the battery/alternator output and also identify where the lost current is going. It will be cheaper in the long run to have an auto electrician look at the charging system. It only takes a few minutes.

SOURCE: volvo s80 dashboard fault

I recently purchased a 2002 S60 D5 which had this problem. I am not a Volvo expert so don't know if it could be the same fault, but it sounds identical. No lights, gauges etc, but intermittently and very briefly comes on. Having heard some silly prices for replacement dash and ECU, I had a look. I found 4 poor soldered joints on the dash circuit board (top left processor & heat sink). I cleaned them and re-soldered them, although I had continuity just after cleaning the corrosion. The dashboard has worked perfectly since (3 weeks) . If you try this make sure you disconnect the battery first or you may have the SRS airbag warning light on! (I had to have it re-set at the dealers!!)

The whole process took less than an hour. If you are not electronically savvi get one of your mates who is to have a look..

Marvin

• 85242 Answers
• Posted on May 12, 2009

SOURCE: need to know what motor oil is best for my 2000 volvo s80 with 150k

any major brand is ok (Pennsoil, Quaker state etc.), use 10W-30W

SOURCE: My 2000 volvo s80 rough idles up and down how can

Have the idle air control valve checked, it might just need a cleaning, or a new one. Check all the vaccum hoses for leaks, all it takes is a pin hole to screw up the sensors.

Testimonial: "THank you so much for your help. I will definitely try this. "

SOURCE: 2000 VOLVO S80 HAS A LARGE VACUUM LEAK. HOW DO I

In the past we have used starting fluid to find vacuum leaks. Start the engine, let it idle. Spray quick shots of starting fluid at your vacuum lines in isolated areas. When the starting fluid find the vacuum leak the engine will react to it... usually by going up in rpm. Depending on your engine computer, it may stall the engine. Either way you will find your vacuum leak. Get starting fluid or "ether" at Autozone or O'Reilly.