Trifecta lights and inaccurate speedo

[StephenVA]

OP: A proper charging system and battery is required before any electrical tests are performed. Anytime battery voltage drops below 9.6v all kinds of faults pop up. As cars get older and on newer cars, the demand on battery capacity gets more extreme. Average life span of a battery is 3 years. If you use a "battery tender/trickle charger" religiously every time the BMW is parked for more than 24 hours, you can get 5-8 years!

You can do a few quick tests before you pull off the alternator to determine battery/charging system failure. At this age and mileage the brushes wear out and give an intermittent to no charge swings, making lots of issues as mentioned.
Step 1. Remove and clean the posts at the battery. Remove and clean the positive jump point under the hood at the driver's side firewall. Remove and Clean the positive cable at the alternator (note: do this step while you have the battery disconnected)
Test one: With a volt meter on the battery posts do the following tests
- Key off, read battery voltage
- Idle read voltage
- 1500 RPMs hold for 1 min and record highest and lowest voltage
- 2500 RPMs see above
Note: You are looking for ANY fluctuation that would indicate charge/no charge, Example volts read 13.7 then drop to 12.3 then up again. It will be normal to see 13.5 to 14.1 for example while running the tests. To make the test simple turn on a few high load accessories (headlamps, heater blower, seats, rear defroster)

Last test
Engine off, turn on headlamps on (key needs to be in Acc position 1) and turn on seat heater, blower on high and rear defroster) for 15 secs or so.

Read battery voltage. If voltage is below 12.6, charge battery. If you have a less than a 15 amp charger, charge over night and reread battery voltage. When cell walls collapse in a battery, the battery will hold only a surface charge then croak when you apply a load over 100 amps for 15 secs. Hence why you need a carbon pile tester to truly test a wet cell battery. Yes there are capacitor based testers that will get you into the 85% range of accuracy for those who follow the tester world.

Note: If your battery has lots of white crud all around the posts, save yourself lots of pain and throw it away before you waste any more efforts...
Note 2: Make sure your ground cables are attached and clean as well. There are a few on the engine, frame points etc. How to test? see image attached)

Report back!

What you are doing here is to see if the battery and charging system are working properly without the proper tools like a carbon pile load tester. This type of tester allows you to properly load a battery and then the charging system to read true out puts rather than SWAG (scientific wild ass guesses) from internet postings. The tests I recommended will take a few mins and it will provide a lot better result than the local parts store's happy meter.

Typical Charging system demands
Equipment Electrical Draw
Rear Window Defroster 25 amps
High Blower 20 amps
Headlamps (Low beam) 15 amps
Windshield Wipers 6 amps
Ignition 6 amps
Brake Lights 5 amps
TOTAL 77 amps


See chart below for battery health results.


Helpful?

[Mark1998]

Will do , awesome info. As background on the electrical system. The battery is a couple years old. The alternator history is a saga. The alternator died 4 years ago 2 hours from home on a weekend. Had it towed and alternator replaced at Canadian Tire( had no choice). 10 months later that new alternator failed, was replaced under warranty. This alternator is now 3 years old but I don’t have a lot trust in it for obvious reasons.
Will complete the tests/ cleaning and report back. Thanks again!!

[StephenVA]

Good luck
Canadian tire was a customer of one of my old companies in a previous life. Well meaning but driven by price first
Alternator was more than likely a reman unit so all bets are off on quality

[Mark1998]

Totally agree on the Canadian Tire comment. That is why I inserted the “no choice “comment. At the time I felt lucky that they had an alternator that fit so I was not stranded.

[Mark1998]

Finally got to do part of the voltage tests. The x5 is off the road now due to a wiper problem.
The vehicle has been sitting for a week, it’s 1degree Celsius. At the battery I started with 11.6 volts. Started it up and have 13.8 volts at the battery, 14.0 volts at the front jump point. With engine at 1500 and 2500 little to no change, maybe .1 of a volt. Engine off , lights on etc. 11.6 volts.
I have not cleaned the terminals at this point. Hope to clear the garage in the next day or so to make room to bring the vehicle in.

[andrewwynn]

the mention of speedo error dictates more than likely your left rear abs sensor is at fault

Do you have a scanner that will show real-time wheel speeds?


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[StephenVA]

Your battery is NOT fully charged. Weak? Will it hold a charge? Who knows.

Needs a recharge with a battery charger. If you have a commercial one (40 AMP output) charge for 45 mins and retest.
Harry Home owner chargers (5-25 amps) you will need 24 hrs for a full recharge.
Retest at rest, then do a surface charge reduction like turning on the high beams, defroster, HVAC blower (high) for 15 secs and then retest. Surface charge only batteries test good until you apply the load. They die like a dog as you can see the voltage drop on a voltmeter going from 12.5 to 10V while the load is on. Anything that will not hold a load at 12V level is ready for the trash can.

Batteries and cold temps are very interesting to say the least.

Helpful?

[andrewwynn]

If the alt is working the weak battery won't trip trifecta. The speedo error is another clue there is a hardware problem.

[Mark1998]

I did change the left rear abs sensor around the same time as my speedo went weird. The sensor was from Rock Auto.
So I finally got her in the garage before the snow hits tonight.
I have a long list;
Remove battery and have it tested. It has a 4 year warranty and it is only a couple days over 2 years old
Reinstall the old abs sensor on the left rear
Clean all battery/ alternator cables
Find out what’s going on with my wipers, grinding noise, can move them by hand.
Fix leaking windshield washer fluid
I have the alternator from the 01, 530 I had. Pretty sure it is the correct one. Confirm it’s correct - maybe install it.

Nice to have a heated garage. 😀

[andrewwynn]

What scan solution do you have? Need to pull codes on the abs


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