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#1006
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Re: Memory dump of ECU
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Since the unit is quite fiddly to get at, I will resist the temptation for the moment. If anybody has a 4WS car already in bits, please post a photo of the internals of the 4WS control unit.
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II |
#1007
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Re: Memory dump of ECU
Phil,
That's what I was thinking, find a spare. There is talk of a 4WS car in a breaker in NZ. I'm sure that you would enjoy looking a 4WS computer over
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#1008
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Re: Memory dump of ECU
Well, my progress lately has been terribly slow. I've been very slowly working on F653 over the last couple weeks. The rev limiter is easy to understand since the work on that has already been done by others. It looks very simple to make a "launch control" for the manual transmission people. It looks like 86c7 and 86c8 rev limit thresholds are used when in p or n. Probably not the most ideal launch control with the hard fuel cut, but an option nonetheless.
I'm still trying to wrap my head around what's happening in the rest of that block. What keeps messing with my head is (1071 (speed) -> al) Quote:
(speed = 0 and the throttle is closed ) or (speed >= 10mph and the throttle is closed) Just seems like a weird set of conditions. I guess now it is time to see what the values this function affects do (1340 11dd 10d1) Oh yeah, this may seem like a stupid question, but does the ecu see reverse speeds as negative? The reason I ask is there is a place where it asks if 1071 (speed) is >= 0, so weather or not the ecu sees reverse as negative would determine it the other path is ever seen in reality. |
#1009
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Re: Memory dump of ECU
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David C. 1996 Laguna Blue Pearl SVX L AWD See my home page for SVX radio install/removal instructions and wiring harnesses |
#1010
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Re: Memory dump of ECU
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Figuring out why it does that is another matter. Speed >= 10 and throttle closed suggests maybe something to do with overrun fuel cut? Looking through the rest of the function I can see it looks at the torque control switch (gearchange fuel cut?). Later it looks at some 2D maps based on coolant temp. (Possibly overrun fuel resume rpm based on coolant temperature). Maybe worth extracting them into excel and plotting a graph to see what shape they are. I suspect that this function is all about various sets of conditions for fuel cut and resume. But I'm just guessing, I haven't studied it at all. Quote:
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II |
#1011
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Re: Memory dump of ECU
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I think it depends whether the branch instruction is BCC/BCS (C flag) or BMI/BPL (N flag). The first would treat the variable as unsigned (0 to 255) the second would treat it as signed (-128 to 127). The highest positive value in a signed byte variable is 127, which is 254km/h - about 159mph.
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II |
#1012
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Re: Memory dump of ECU
I pulled my 4WS unit today and opened it up to have a look. It's a big unit, about double the size of a TCU.
It has a MH73308CP8 microcontroller. That's a custom made and undocumented chip. The CPU core is probably something familiar, but as I can't read the ROM, I can't even try to guess. There are very strange looking vertical white boards containing component's I've never seen before. Like little squares of silicon. I don't see any provision for external memory, so probably not possible to reprogram it. Certainly not easy. Some of the capacitors are leaking brown goo, which doesn't bode well. Reminds me of the ones on Dell PC motherboards.
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II Last edited by b3lha; 02-13-2010 at 03:46 PM. |
#1013
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Re: Memory dump of ECU
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Field effect transistors Q16, 17, 18 & 19, provide motor switching. Motor current is sensed via voltage drop across O,3 ohm resistor R79.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#1014
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Re: Memory dump of ECU
If you're talking about the cluster of 6 electrolytics near the toroid coil, that looks like glue applied during manufacturing.
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David C. 1996 Laguna Blue Pearl SVX L AWD See my home page for SVX radio install/removal instructions and wiring harnesses |
#1015
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Re: Memory dump of ECU
Better eyes than mine. ---- Yes it does. It is there to join the ectro's together and prevent vibration causing fatigue breaks in connections.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#1016
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Re: Memory dump of ECU
Thanks Trevor, that's good information. Any idea about the little white boards shown in the final photo?
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II |
#1017
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Re: Memory dump of ECU
OK. I hope that's what it is.
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II |
#1018
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Re: Memory dump of ECU
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Often small custom made sub assemblies are attached, as means of economical and convenient assembly of a complete board. If you are in the mood, a side on photo showing the detail could help. Regards, Trevor.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#1019
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Re: Memory dump of ECU
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It's nice to know how to talk to the unit and log its data for diagnostics. Even if it could be modified, I'm not sure I would attempt it, as it is rare to the point of irreplaceability. I think as far as the hardware goes: if it ain't broke, don't fix it. The only computer on my car that I haven't yet managed to talk to is the cruise control unit. I know the command byte is "AB", but I haven't found the trick of making it talk yet. Does anybody know whether the latest Subaru Select Monitor can talk to the pre-OBD2 cars? The one that has update CDs rather than cartridges. I may be able to borrow a laptop with the SSM3 software, but all the cables with it are OBD2 connector. I suspect our cars may be considered obsolete and unsupported.
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II |
#1020
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Re: Memory dump of ECU
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I think you are dead right in presuming that the IC is application specific. I have never run across such an animal. The sub board has some very wide tracks and links, which indicates that substantial control currents are involved. Overall, that is some box of tricks. A wild thought, --- could the ASIC be involved with inertia!?? In what plane would it lie when mounted in the SVX chassis. Is there any mechanical, optically, or whatever, device associated with the ASIC? Cheers, Trevor.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
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