Question about 1990 Volvo 780

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How to reset alarm on a Volvo 780 so it will start?

Battery died. I replaced the battery and now the alarm goes off and the ignition won't turn over?

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  • 2 Answers

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Posted on Jan 02, 2017

  • 818 Answers

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.

Posted on Sep 17, 2008

  • 77939 Answers

SOURCE: Alarm sounds everytime key removed from ignition?

There is a switch either in or on the driver door that turns on the interior lights and tells the module the door is open and the key is still in the ignition, this sounds the alarm, check all the doors and make sure they turn the interior lights on and off when the doors are opened and closed.

Posted on Nov 21, 2008

  • 1 Answer

SOURCE: 91 volvo 240 won't start after long trips/multiple short trips

If you mean that when you try and start it the engine actually turns over but does not start, then check out the following info (I had a similar problem on my 1989 Volvo 240. It would start fine sometimes, other times it would not start even though it would crank) . It turned out to be the fuel pump relay. 
When you try starting your car and you can not hear the fuel pump turned on (sound coming from the left underside of the car in front of the left rear tire), do the following if you think this is your issue (no cost for trouble shooting and takes 10 minutes to do):
The fuel pump relay is behind the access panel under the glove box. The panel is easy to remove - just unscrew each of the 5 panel knobs/fasteners a quarter turn and the panel comes out/down.  The fuel pump relay is a white plastic cartridge with a wire harness going to it. Just unclip it from the metal clip that retains it and leave it hanging there. When the car doesn't start and just cranks, lean over and tap the relay while you are trying to start the car (tapping it shakes the contacts inside that would normally switch over to complete the circuit when it is energized). If this is your issue and you can repeat the solution by tapping the relay when starting the car, buy a new one (I got mine at for around $14) and kept the old one in the trunk just in case.
Hope this helps.

Posted on May 28, 2009

  • 1871 Answers

SOURCE: I replaced the battery in

Hello! Tell me Is the hood open or closed? Do you have a spare door key?
If the doors are locked, the hood is closed, your key will not unlock the doors, and neither will your spare...Your going to need a locksmith...

Send a comment with a full description as to what happened and I'll attempt a fix...........Guru...........saailer

Posted on Feb 24, 2010

  • 1 Answer

SOURCE: Volvo S60 R will not

Pull the immobilizer fuse.wait one minute then reinstall.This only works 75% of the time.

Posted on Mar 22, 2010

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