# 18010/P1602/005634 - Power Supply B+ Terminal 30: Voltage too Low



## jbdubn (Feb 3, 2009)

My AEB 1.8t always has this code. The only time it doesnt is when i clear the code while the car is running, then check again its gone. But when i turn the car back on the code comes back. 

Yes i have read this: http://wiki.ross-tech.com/wiki/inde...ower_Supply_B.2B_Terminal_30:_Voltage_too_Low

Its a new battery. Connections are good. 
I have not ruled out the alternator, but its been like this for a year and still not a dead alternator.

What voltage does the ecu have to see before this code comes on?

Anything else it could be? Bad ground to the ecu? Bad ground elsewhere?


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## Uwe (Jan 16, 2000)

Find the system voltage that your ECU "sees" in the measuring blocks and compare it to the voltage a meter shows at the battery. 

-Uwe-


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## jbdubn (Feb 3, 2009)

Ok. I am not sure that I can do that without the car running. Basically what im trying to to is figure out why i cannot connect to the ecu with the engine off ignition on. I figured this fault code has something to do with it. 
What voltage does the ecu have to see to connect through vagcom? I can try and check right at the ecu while the engine is off and ignition on. I know i am getting constant and a switched power source to the ecu. I assume im checking the switched power source. 
I will post back later on tonight after i check to see if i have different voltage readings between engine running and engine off key on. 

If somebody has the info on what the ecu needs for voltage to connect that would be great.


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## Uwe (Jan 16, 2000)

10 Volts should be enough for the ECU to communicate. 

-Uwe-


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## twin2626 (May 11, 2006)

My car has the same fault 
i also have a new battery and clean terminals but when I turn my headlights on or something else that uses a decent amount of power the car idles a little rougher 
Maybe the alternator but it still works so I'm not going to replace it


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## animaniac (May 26, 2005)

Check the engine management fuses and the ecu relay!


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## jbdubn (Feb 3, 2009)

I checked all the fuses and the Relays. All seems to be good. Any other ideas?
I have verified all my ecu connections again. I have power and ground to all the appropriate pins. I have a constant 12v to the ecu but i still get this code. ....?


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## NL TECHNO (Apr 14, 2021)

jbdubn said:


> My AEB 1.8t always has this code. The only time it doesnt is when i clear the code while the car is running, then check again its gone. But when i turn the car back on the code comes back.
> 
> Yes i have read this: 18010/P1602/005634 - Ross-Tech Wiki
> 
> ...



BATTERY NEEDS CODING WITH VCDS !!! 
Audi A6 C6 3.2 fsi Quatro with Bosch S5 013 (100Ah / 830EN) looks like
Part Number :* 4F0915105C *
Serial Number : *600402083H* or 600402083S
Vendor : *VARTA*


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## chrisqc (Aug 7, 2008)

NL TECHNO said:


> BATTERY NEEDS CODING WITH VCDS !!!
> Audi A6 C6 3.2 fsi Quatro with Bosch S5 013 (100Ah / 830EN) looks like
> Part Number :* 4F0915105C *
> Serial Number : *600402083H* or 600402083S
> Vendor : *VARTA*


This thread is 11 years old. AEB Passat does not have the capability to code the battery to the car.


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