[losvre]

Hello to everyone,

I own a GT TDi 110 and although I have been a member for some time now this is my first post.

Something strange happen to me this morning. While I was driving to work, all the instuments went off, tacho, fuel, coolant, everything. At the same time the ABS, Airbag, battery and caution red light came on. I stopped over and shutt off engineand had a ckeck. Since the engine was working fine I decided to continue to my work with no indication on any of the instruments. As of a sudden, all the instruments came back and only the airbag light still ON.

After 2 days I stranded just when arrived at a wedding of a friend! When jump started the car I can drive it but checked the voltage and is only high enough to charge the battery at high revs, 2500 onwards?
What do think/suggest?

Thanks
Nikos

 

[chittychittybangbang]

Have it tested, any shop has a tool to test both the alternator or the battery without even removing them from the car. This sounds like it could be the alternator or voltage regulator. I don't know if your car has an alternator pulley clutch but if you counterhold the fan inside the alternator with a stick and turn the pulley, it should only turn 1 way.

 

[almir]

check for loose battery terminals, also in the morning before starting the engine measure voltage of the battery. Good battery should have 12.67V
if you see 12.1 or lower battery is not charged or it is old and not holding charge.

then when you start the engine use multimeter tester to test voltage at the battery again it should be over 13.5V, this will tell you if alternator is charging.

also clean all battery terminals, and main engine ground terminal on the engine.

 

[Seatman]

There's also a wire from the alternator to the battery, check it isn't damaged, you could test it for continuity with your multimeter.

 

[TDILow3]

The de-commissioning and re-commissioning of the instrumentation, ABS, air bags...is the symptom of a low voltage event, either a low battery charge state (alternator fault or a dead cell in the battery) or a loose connection in the electrical bus causing the electronics to shut down and restart when the voltage return to normal. I would use the KISS method and start with the easy and no-cost inspections:
a) Battery Voltage: Engine not running 12.5-VDC or better; engine running 13.7 to 14.1-VDC

b) Cranking Battery Voltage: If the battery voltage drops below 10-VDC during the crank cycle, but reads above 12-VDC when not being cranked: dead cell or loose/dirty battery connection

c) Loose Connections: Look for any loose electrical connections at the alternator, battery, fuse panels... Sometimes a loose connection will arc and leave you very tiny burn marks to spot the loose connection.

If your multimeter has an 'auto range' function, disable it and set the range to measure down to 1/10 of a volt. The reason is that the auto ranging feature on a multimeter will cover up short-lived events and normalize the data to give you a clean value, which is not what you want. By going to a fixed voltage measurement you will increase your ability to see quick voltage changes, which may be causing your electronics to re-commission.

 

[Keithuk]

Welcome to the forum. welcometomyturbodies

The thing is once the engine is running the battery isn't being used only as a reference to system voltage. Everything on the vehicle that uses electrical power should be fed straight from the alternator. You say you instruments went off thats more like a bad connection on the feed or earth you need to check them both.

You can do your own simple check on the condition of the battery. If you remove the stop feed of the pump remove so the engine doesn't startup and all the battery filler plugs so you can see the electrolyte and get someone to crank the engine over for 10 seconds while you have your multimeter connected to the battery terminals. Look inside each cell and see if one particular cell starts to bubble if it does then that cell is the bad one. As mensioned the terminal voltage under cranking should drop below 10v, if you have a bad cell the voltage will drop below.

 

[astavros]

How old is your battery? A good alternator will mask a tired battery up to a point, if its really your battery you should be able to repeat the symptoms by turning everything on with the engine at idle. Also any corrossion around the terminals, (white powder) or are they clean, loose or oxidation at the battery terminals will create a poor connection there and make the battery look bad.

Although to be honest if you have white powder around either battery terminal that means the terminal is leaking battery acid at the base and causing the corrosion and the battery should be replaced anyway.

If you have a DVM (voltmeter), with everything off measure the battery voltage if its less than 12V then get a regular battery charger and charge it for 3 -4 hours at the 10Amp setting or overnight at the 2Amp setting. then recheck if its still under 12Volts your battery is bad...replace it.
If its more than 12V after charging then with the engine OFF try turning on all the electrical stuff, all the lighs, windshield wipers, heater blower on high, with your DVM monitoring the battery voltage it should hang in (stay above 12V even after ~5minutes of this load, if it does then your alternator is bad or more likely the regulator that is built into the alternator is bad.
If the battery voltage drops below 12V after a few minutes then the battery needs to be replace
Good luck