New member. Hi There
Help.
Recent purchase, 2005 XC 90 T6 Engine
Purchased the car and the owner was up front about a Alternator issue. New unit wrong Voltage Regulator. Checked up online and I changed to the supposed correct regulator.
Better but still the battery light would return now and again.( even with the warning light on shows charge at the battery )
Week ago while driving dash lights started to appear, battery, ABS, brake failure, etc. then the speedometer stopped working and finally the car ground to a halt.
tried to restart but dead battery.
Walked home took a second battery and she started right up, no lights. Ordered a new alternator just in case.
while waiting for the alt to arrive found a gas leak at the fuel sender, ordered a replacement and to cut what is becoming a very long story, installed this unit a couple of times as the replacement also had a leak. thinking i had fixed this issue I went to test the leak.
Car started but only for a few seconds. I noticed the fuel level was extremely low which was not right as the sender worked fine to start with.
I gained access to the fuel pump all looked good and after powering up the pump externally the pump started making more noise than at first. after this the car ran as before.
seems like the pump was not getting the correct voltage. also the gas gauge was still reading low for the amount of fuel in the tank.
now car starts is charging OK but I still have brake failure and the ABS light on.
Questions
1 Why would a car that is running and charging drain the battery? ( Both battery's used have been tested with a load tester )
2 Is there an electrical part on my car that controls voltage to the various systems? ( just thinking that lights came on when my battery was going low )
3 Why did I buy this car?
Regards Richard

 

1. Because the alternator is not recharging the battery. Either the alternator itself has a problem or connections from the alternator to the battery have a problem. What voltage does your load tester indicate at the battery when running?
2. Yes, the voltage regulator (in the alternator) Warning lights come on as the battery goes dead - once the voltage gets too low for say the ABS system to work properly - there's a red light that says - Hey i'm not working anymore!
3. That's a good question.

 

Thanks that the reply.
The voltage at the battery when running is between 13.4 and 14,2 or around those numbers. I'm assuming at different state of charge ) the proper Volvo battery after charge show 12.4 on the bench and holds up nicely when a load is applied.
So with the car running battery charging I still have lights etc. checked the codes. None ( at this time )
Richard

 

Which modules did you check the codes on? With what scan tool?

Lights - are these still on? - "battery, ABS, brake failure, etc"

ABS and brake failure means there are codes probably in the abs control unit.

Battery light - A basic alternator circuit has a fat red charging wire to the battery, a ground connection (usually the case) and the small D+61 wire that would go to the warning light on the dash. When the voltage in the battery was higher than the voltage coming out of the alternator - the light would come on. That's not what you have.

The d+61 wire on your alternator (labeled B:1 on the diagram) is connected to the CEM and using a LIN -bus system controls the charging rate. Not sure what alternator you have installed - but I'd bet the regulator is not capable of communicating on the LIN bus. (local interconnect network)

 

Hey there . Thanks for your persistence.
no batt light now just ABS and brake failure.
Alternator new but came with the wrong Voltage reg. I have switched to the correct one. The Batt light stayed off for a week then intermittently came back on every time i checked the batt is was indeed charging
My alt has indeed large red and one small other wire.
Yesterday i disconnected the alt completely and ran it with no charge, No change at all.
I am not expecting lights to be on when its running with a batt showing over 12 volts, even without the alt connected.
As for my scan tool. very basic. able to read whats there and clear codes. Not sure how to access a specific module.
Richard

 

Here's a diagram of all the modules that could be in your car. Most of them are. (you probably don't have a PHM (phone) or SUB (subwoofer)

A compatible scan tool can talk to all of those modules. A basic scan tool is usually just for emission related codes and can usually only communicate with the ECM and TCM (engine and trans control units)

 

Thank you very much for the info. Now i will have to learn what they all stand for.
Quite a few...
Cheers Richard