Alright. So, a VERY long story short, we got this 1998 Volvo S70 numerous years ago. It was fine for a while, then the fan would kick on randomly and drain the battery. It ended up sitting for a year or two, but now it's time to get it up and running again. I did some research and found that people said the fan issue was caused by a bad coolant temp sensor. So, I got one of those, and a new thermostat, and replaced them both. Problem fixed, right? Wrong. After all that, it ran great for like, a month. I could walk outside after not starting it for a couple days and it'd be fine. Well, it was left sitting for probably around 11 days and is now dead as a hammer... Again. It had a brand new battery in it, as well. During the month that it ran fine, I noticed the "ABS" and "TRACS" lights would come on randomly, then shut off randomly. I did MORE research and found out that that is caused by a bad ABS module. So, it needs a new ABS module. That's okay. But my question is, what's draining the battery? Would the bad ABS module be doing that? Is there something else I need to look for? Any help is greatly appreciated.

 

S70's are notorious for having a hair trigger trunk release on the key fob. Trunk light stays on, battery dies. They don't open much, you may not even notice it unless you hit a bump and the trunk open light will flicker. walk around back and lift up the trunk lid with one finger.

 

Something else is drawing enough to drain the battery. The Tracs/ABS light should not do it. Our 850 had it on for three years and never effected any other system in the car.

 

Close all the doors, ignition off, disconnect the negative terminal on the battery. Get a Volt, Ohm, Meter and connect it between the negative post of the battery and the negative battery cable. Set the VOM to read amps (highest amp setting such as 10). Now you have a circuit and you should see the meter display number of amps drawn. Have a helper pull one fuse at a time to see if any of the cars circuits is drawing the majority of the current. This should isolate the problem. Keep in mind you may have to set the cars alarm system by locking the doors and engaging the hood lock with the hood open. I had a 1997 850 that had a similar issue with eating batteries every year. It turned out to be the alarm was somehow draining the battery.

 

Had the same problem on my 99 S70 T5
I found that a microswitch on the rear drivers side door was faulty, leaving the courtesy lights on whenever the switch wanted to, somehow the all the interior lights were turned off, so I did not notice this until it the locks started popping up when you put the car in gear. I disconnected one of the rear courtesy lights that had a broken switch, replaced the actuator and it has never happened again. i cannot pinpoint exactly who or what was the culprit, but in this case all I changed was those two things and the main switch ( drivers door switches) again, it might not be your solution, but it might be points to check..

 

Alright guys, new problem. Everything above has been fixed. It runs like a top, and everything checks out... Except one thing. Around the ignition switch there's a circular green light that stays on 100% of the time. I think it may be draining the battery a little bit. Is it supposed to stay on all the time, or has a new problem arisen? The car never has a problem starting, but sometimes it takes a few seconds of turning over to actually start. Is this anything to worry about? It's got a brand new battery in it. Less than 3 months old. Help.

 

That light is suppose to come on when you open the door and go out after about 30 seconds or when you insert the key. It probably pulls so little power that I doubt it would drain the battery in a day or two. Probably more like 3 weeks. Also, try to check and make sure the glove box light is not staying on and draining the battery.

 

Hmmm.... I never stood there for 30 or so seconds and see if it goes off... I should run out and see now. How would I go about seeing if the glove box light is staying on? When I open it, the light is supposed to come on anyway, right?

 

Yes, sometimes you can see it at night.