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Discussion Starter #1
Hi Everyone,
The battery light on my 1.9tdi T5 is permanently on. I recently changed the alternator as the last one failed. When I started the van the light went out for a few seconds then came back on and has stayed on ever since. I am registering 14+ volts when the van is running.
I have tried disconnecting the leisure battery and the VSR but still the light remains on. I also replaced the exciter wire connector at the alternator and cut the wires back into the harness as I was concerned there may be a break in the exposed wires.
I am totally flummoxed by this one and any suggestions or previous experience of this will be gratefully received.
Thanks
 

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140 DSG Shuttle SE full Camper
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Hi Everyone,
The battery light on my 1.9tdi T5 is permanently on. I recently changed the alternator as the last one failed. When I started the van the light went out for a few seconds then came back on and has stayed on ever since. I am registering 14+ volts when the van is running.
I have tried disconnecting the leisure battery and the VSR but still the light remains on. I also replaced the exciter wire connector at the alternator and cut the wires back into the harness as I was concerned there may be a break in the exposed wires.
I am totally flummoxed by this one and any suggestions or previous experience of this will be gratefully received.
Thanks
Probably a fault with the alternator, check the voltage at the indicator light connection on the alternator with the wire disconnected, it should be the same as the main output voltage when it's running.
 

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Discussion Starter #3
Probably a fault with the alternator, check the voltage at the indicator light connection on the alternator with the wire disconnected, it should be the same as the main output voltage when it's running.
OK thanks. I'll give it a try. I just assumed that would be OK as I'm getting the voltage at the battery
 

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Discussion Starter #4
Hi Roger,
Checked the output today 14.4 volts from the blue wire output so it's definitely not the alternator. I'm guessing either a wiring fault or the diode to the battery light.
Anyone else had anything similar?
Thanks
 

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Discussion Starter #6
Sounds like the regulator on the alternator. If it’s more that 14.4v then that’ll be it
Hi, Thanks for the response.
I'm getting a steady 14.3 - 14.4 volts output from the alternator and I've checked the output to the lamp, following Roger's suggestion, which is at the same voltage so I'm pretty sure the regulator is OK. I would have thought if I was getting more than 14.4 the battery warning light would still go out - or at least do something other than be steady on.
Have to admit this one is driving me nuts. At the moment I'm thinking of running a complete new wire from the alternator to the back of the dash once I figure out how to get it out.
 

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I think that wire to the dash (the blue DF wire) runs through the ebox under the battery then on to the dash if it is like the 2,5. On the 2.5 the J519 box under the dash on the drivers side is part of the system also. If you want to track the problem down yourself you would need to confirm continuity between the alternator and the ebox and then onwards to the J519 and the dash. Don't forget to check all fuses and earths before bothering to go further.

If you have VCDS I would be interested to know what it says 'Battery Voltage' is in the J519 controller and also in the engine ECU too.
 

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Discussion Starter #8
Hi,
Thanks for the advice. I really hate electrics at the best of times and this one is driving me nuts. I'll check the connection to the ebox and fuses but after that I'm thinking it needs expertise.

Any suggestions on how I can best get the circuit tested as I can't help but think it is more than just a wire chasing excercise? I live in Leamington Spa and there is a VW specialist nearby so maybe they can do a check using a VCDS.
 
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