RomRaider

Good afternoon gentlemen!

I'm trying to figure out how to disable some Hitachi's ROM MY 06-08 CEL routines. It looks like CEL routines table can be found by searching byte sequence "01 17 01 18" and has length of 0x400 bytes. And it differs even visually from Denso's. I disassembled and looked at the code. I found that it also differs from Denso's ROMs - in Denso ROM there is DTC table or switch, which controls creation of corresponding CEL routine. In Hitachi ROM as far as I figured there is neither DTC table nor DTC switches and all CEL routines are always built.

So, I had a question. Is it possible to disable particular CEL routine in Hitachi ROM? As far as I understand, in Denso ROM if DTC switch set to zero, that CEL routine creation is skipped. Maybe in Hitachi ROM routine also can be skipped, for example, by placing zeroes instead DTC number? Did someone try that? Or maybe there is some other way?

Hi, Did you get any further with this?
Did you try to zero out DTC number?

No futher progress. I'm sure that zeroing won't help. Hitachi ROMs look a bit like Mitsubishi ROMs, and Mitsubishi uses so called Options Set bits to control ECU behavoir. The starting point should be OBD routines, but my skills are bad.