Unfortunately, I don't think that simply unhooking the battery will do it. There are 2 batteries and there will probably still be residual pressure in the reservoir. Don't know if anyone has found a safe way to do it without the appropriate software, but I haven't heard of anything.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record