Battery
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Battery
Hi, I’ve just done the timing chain job after all the works done the batteries dead jumped and start car no problem, the next day disconnect the battery get it charge at auto zone after installed the battery the car start right on, later on I’m getting message the alternator at fault cannot charge the battery the next day the car is dead no power at all. What is the problem pls.help thanks.
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Joined: Dec 2001
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From: Georgia
Alternator fault. Seems pretty direct. But is it an electrical, mechanical, or thermal fault? Do you have a diag tool like VCDS or OBDeleven so you can read measuring data to see what's actually what in regards to the charging system?
With the engine running, what voltage do you read between the B+ post on the back of the alternator and the alternator housing (which is grounded to the engine, which is grounded to the chassis). One, is the alternator producing voltage. Two, is the alternator producing the correct voltage. Three, is that voltage getting to the chassis (what's the voltage between the jump start posts when the engine is running, does it match the alternator produced voltage, etc).
With the engine running, what voltage do you read between the B+ post on the back of the alternator and the alternator housing (which is grounded to the engine, which is grounded to the chassis). One, is the alternator producing voltage. Two, is the alternator producing the correct voltage. Three, is that voltage getting to the chassis (what's the voltage between the jump start posts when the engine is running, does it match the alternator produced voltage, etc).
Thread Starter
AudiWorld Junior Member
Joined: Aug 2021
Posts: 9
Likes: 0
Alternator fault. Seems pretty direct. But is it an electrical, mechanical, or thermal fault? Do you have a diag tool like VCDS or OBDeleven so you can read measuring data to see what's actually what in regards to the charging system?
With the engine running, what voltage do you read between the B+ post on the back of the alternator and the alternator housing (which is grounded to the engine, which is grounded to the chassis). One, is the alternator producing voltage. Two, is the alternator producing the correct voltage. Three, is that voltage getting to the chassis (what's the voltage between the jump start posts when the engine is running, does it match the alternator produced voltage, etc).
With the engine running, what voltage do you read between the B+ post on the back of the alternator and the alternator housing (which is grounded to the engine, which is grounded to the chassis). One, is the alternator producing voltage. Two, is the alternator producing the correct voltage. Three, is that voltage getting to the chassis (what's the voltage between the jump start posts when the engine is running, does it match the alternator produced voltage, etc).
Ok I will check that later I don’t have vcds I have Carista and old OBDeleven but I don’t have adroid phone or tablet anymore I have to check some friends. Anyway the autozone guy said battery still good but I check today with my obd battery test almost dead lights is blurry only half of the letters , the amps is zero I was thinking imight be battery?
thanks
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AudiWorld Super User
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From: Georgia
A discharged battery and a bad battery are not the same thing. If the charging system is not working, then nothing is charging the battery, so of course it's a one way street to discharged. You additionally might have something constantly draining the battery even when the car is off. Pull the battery out, put it in a proper tester/charger. If the battery can restore to a full state of charge (and can pass a load test), it's not your battery. You need to find out if something is a constant drain (with the battery out, put a continuity test across the battery terminals, if it tests continuous then you have a permanent drain on the battery that you should hunt down). Otherwise, back to your original problem of a failed charging system.
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From: Georgia
It's a LIN bus managed alternator, bench testing it requires an appropriate tool that can actually communicate via LIN. Your dealership won't be able to properly bench test it either, 99% chance. That's why it's easiest to use the diag tool and monitor the communications as best can be monitored using the J533 measuring blocks to confirm the status state and commanded voltage and returned values, etc. Be more thorough to have a LIN sniffer on the bus, but the measuring values are usually sufficient.
Thus start by just measuring the voltage observed in the places I noted to see what's actually happening in the car at the basic level.
Thus start by just measuring the voltage observed in the places I noted to see what's actually happening in the car at the basic level.
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Joined: Feb 2010
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It's a LIN bus managed alternator, bench testing it requires an appropriate tool that can actually communicate via LIN. Your dealership won't be able to properly bench test it either, 99% chance. That's why it's easiest to use the diag tool and monitor the communications as best can be monitored using the J533 measuring blocks to confirm the status state and commanded voltage and returned values, etc. Be more thorough to have a LIN sniffer on the bus, but the measuring values are usually sufficient.
Thus start by just measuring the voltage observed in the places I noted to see what's actually happening in the car at the basic level.
Thus start by just measuring the voltage observed in the places I noted to see what's actually happening in the car at the basic level.