ECU problem? 5v at Sensor ground(B16)

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ECU problem? 5v at Sensor ground(B16)

Postby feelin_raudi on Tue Mar 03, 2020 5:17 pm

I'm on a college FSAE team and we're having an unusual issue with our M400 ecu. We actually have two identical ECUs. During assembly of our car this year, we had some electrical issues. Some shorts and blown fuses, etc. After trying to start, we found that our sensor ground(B16) is at 5v instead of 0. We checked for shorts in the harness but couldn't find anything. So we tried our other ECU running an identical config(literally just copy pasted), and sure enough, it's 0v at B16. We reflashed both ECUs, and nothing changed. It seems like there might be an internal problem shorting B16 to a 5v supply. Has anyone ever experienced anything like this? Any common issues we should be aware of? Thanks in advance! -Ivan
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Re: ECU problem? 5v at Sensor ground(B16)

Postby Blu302 on Sun Mar 29, 2020 8:27 pm

It is from the internal ground link being blown. Too much current has passed through the ground and blown the internal fuse link. They run a fuse link from the sensor/aux etc grounds to the main ground inside the case. This stops bigger problems from over-current killing the board.

I have done this from passing too much ground current from my ignition coils through the sensor ground.
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Re: ECU problem? 5v at Sensor ground(B16)

Postby Vlad on Fri May 01, 2020 12:32 am

Check on the mainboard if the pads soldered in the picture i’ve attached are blown.
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Re: ECU problem? 5v at Sensor ground(B16)

Postby SprinterTRD on Mon May 04, 2020 8:35 am

You should not solder bridges across the pads.
Doing so may permanently damage the ECU if you have a short to +12V.
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Re: ECU problem? 5v at Sensor ground(B16)

Postby Vlad on Fri May 29, 2020 7:05 am

I know...this is how i got the ecu in the shop...
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