Warning lights come and go 2001 V40 80k miles

anordheim · Post by **anordheim** » 18 Dec 2006, 12:07

I know a few others have brought up the topic. However, I've had some issues with my 2001 V40 80k miles over the last few weeks. Seems like the voltage regulator in the Alternator is malfunctioning causing all the electronics to fail at times while driving. However, the car has been fine the last couple of weeks. I've measured the power to my cigarette lighter output and it reads between 13.5V to 13.9V while the car is running depending on what accessories I have running.
My main question is that service lights have come on and gone off during this period. The ABS light was on for a little bit yesterday but went away by itself. However, the Airbag light came on and has stayed on for a couple of days. Anyone have any recommendations to what may be going on? I've spent so much money replacing O2 sensors, brakes, etc. over the last month and can't really afford any more to go wrong.
Thanks for your input!

Post by **MadeInJapan** » 18 Dec 2006, 12:14

Try disconnecting your battery for several minutes to see if all of the lights go off. Seems you've had an electrical glitch...maybe your battery got drained somehow. Don't know how it is on your car, but you may need the radio code to activate it again after this procedure, especially if it's an SC-815/815 series radio. Good luck and let us know how things go.

Not sure, but I don't think your car is prone to the ABS module issue the 850's and 70 series (earlier versions) were.

anordheim · Post by **anordheim** » 18 Dec 2006, 14:17

I tried disconnecting the battery for about half an hour. Yes, the radio required the code to be inputed. Not a problem since I have the code.
The Airbag light shut off with the rest of the dash lights but came back on immediately as the engine started. Now it stays on through the entire power up cycle without as much as shutting off for a second. This is how it's been the last few days.

anordheim · Post by **anordheim** » 19 Dec 2006, 21:00

Any other ideas?????

Post by **MadeInJapan** » 19 Dec 2006, 21:24

Wow...strange things abound.
Whenever strange electrical glitches occur, it's usually something to do with the battery and/or charging system. Measure your battery's voltagel. It should read 13+ volts. If it's below this, the battery could be your problem. Others might be able to give you better advice on this. Other than this, have you tried having your codes read? Even if there is no check engine light (CEL) on, there still might be codes stored. You can have this done for free at most any autoparts store. Just report back on any codes that you get. Come to think of it, most autoparts stores will check your battery and charging system too.

anordheim · Post by **anordheim** » 19 Dec 2006, 21:33

MadeInJapan wrote:Wow...strange things abound.
Whenever strange electrical glitches occur, it's usually something to do with the battery and/or charging system. Measure your battery's voltagel. It should read 13+ volts. If it's below this, the battery could be your problem. Others might be able to give you better advice on this. Other than this, have you tried having your codes read? Even if there is no check engine light (CEL) on, there still might be codes stored. You can have this done for free at most any autoparts store. Just report back on any codes that you get. Come to think of it, most autoparts stores will check your battery and charging system too.

The battery is almost brand new and read well over 12v without the motor running. I've checked the voltage with the car running and it seems to vary from 13.3-13.8v depending on what I have running. A friend of mine ran the code scanner and came up with a problem with the coolant thermostat which I replaced myself tonight. However, the ABS light is still on. Car runs very smooth and nice. However, as I said there was a couple of days about a month ago where all the dash lights came on during driving, the headlights started to fade, windshield wipers slowed down and the automatic transmission didn't seem to have enough power to run properly. I can also see the LED's behind the dash blink in tune with the turn signals which seems like a voltage problem to me.
You think it could be the Alternator??????

Post by **MadeInJapan** » 19 Dec 2006, 21:42

The voltage is right...you did the thermostat and the ABS might be the same issue that my S70 and the 850's have had...don't know if yours is the same. I checked Victor's site (the guy who rebuilds these) and he has 2000 S40's listed but not '01's, so if yours has a bad module, at least I know that he doesn't repair them.

The alternator certainly could be the issue but I'm thinking more in terms of some type of short...or maybe corroded ground wires somewhere- even off of the negative battery cable. It seem that it will be difficult to fault trace this one. Anyway, get the charging system/alternator checked.

anordheim · Post by **anordheim** » 19 Dec 2006, 21:53

MadeInJapan wrote:The voltage is right...you did the thermostat and the ABS might be the same issue that my S70 and the 850's have had...don't know if yours is the same. I checked Victor's site (the guy who rebuilds these) and he has 2000 S40's listed but not '01's, so if yours has a bad module, at least I know that he doesn't repair them.

The alternator certainly could be the issue but I'm thinking more in terms of some type of short...or maybe corroded ground wires somewhere- even off of the negative battery cable. It seem that it will be difficult to fault trace this one. Anyway, get the charging system/alternator checked.

What's the best way to get the Alternator checked??

Post by **MadeInJapan** » 19 Dec 2006, 22:03

Free check of the charging system at Autozone...that's what I would do. That would tell you if it's the battery or alternator. My concern however is that it's something else- like a ground wire off of the negative side of the battery or some bad ground connector in the dash. At least you can eliminate one issue and it could very well be the alternator. Could even be a loose service belt that isn't helping the alternator do it's job...hard to say, but start plugging away at it and you'll figure this thing out.

anordheim · Post by **anordheim** » 19 Dec 2006, 22:15

MadeInJapan wrote:Free check of the charging system at Autozone...that's what I would do. That would tell you if it's the battery or alternator. My concern however is that it's something else- like a ground wire off of the negative side of the battery or some bad ground connector in the dash. At least you can eliminate one issue and it could very well be the alternator. Could even be a loose service belt that isn't helping the alternator do it's job...hard to say, but start plugging away at it and you'll figure this thing out.

Thanks, I will go to Autozone first.
One more thing. The problems with the lights coming on like that seems to always happen when it's cold outside. The light came on Saturday morning which was a day with temperatures down to 28 degrees. This has seemed to be a pattern. Any thoughts around this?