I was talkin to a guy in class a few days ago about how to reset a car's ECU. He told me that his 92 VW Passat had a small hard drive with the ECU that stored all the car's data so disconnecting the battery wouldn't work.

I have never heard someone associate a hard drive or any other 'permanent' storage device with an ECU. My understanding was that the ECU has a ROM chip (that stores factory base operating data) and a RAM chip that stores car feedback data that is used to modify engine management (e.g. timing, a/f curves).

Can someone give me an idea of how the ECU stores data? thanks.

 

I think your friend is full of shat to be honest.

 

Me too. But I am the first to admit I don't know everything, so I figured I'd ask.

I'm afraid I must point out that he is not my friend. He is a guy in my class, if I weren't stuck in class with him, I'd never talk to him at all. He rubs me the wrong way, personality wise.

 

Most cars have a PROM chip to run everything and a few RAM chips for memory storage. I have a hard enough time keeping a HD in Comp working, I could not imagine one in a moving, vibrating, hot, and cold car.