DaveT

Yes, there is a crystal right there. I'll check the frequency. I have one of those plug in breadboards, so it is possible to pull a cpu and wire it up on one of those without having to spend for a PCB. I can try tracing out the LED. I also want to figure out which wires on which connectors are power and GND.

yep, either one of those pretty much make it clear. Add in the WOT on top of the other manageable conditions, no doubt.

You might have to crop them or resize to get them under 2megabytes so the forum will allow upload.

That this is a swap, adds another layer of unknowns - as in correctly wired. The power travels that path, the white wire goes to one end of a link, the other end of the link goes to the battery through another wire. The link box pops right out of the slot on the tank, so it should be pretty easy to trace. Yes, sometimes someone is close enough to look, first hand is nearly always faster. The rectifiers are semiconductors that change the AC that the alternator generates into DC that can be used to charge a battery. They are inside the alternator. alternatorparts.com sells all of the internal parts for alternators.

Looks like MPFI to me. Turbo compresses air before it hits the throttle body / manifold, no? I think the turbo would be to the left & rear of the air tube in your picture, kind of hard to miss.

Headgaskets & reseal, expensive to pay a shop for. Lots of us on the forum have done it. I've done it a number of times. There are a lot of threads with all of the tips and tricks. Maybe not the best thing for a first time project, but if you have a space and the time, you will learn a lot.

11.5V is not charging, it's running off the battery. You want at least 13.8V at the battery terminals to be charging in a car situation. Check the heavy white wire that connects to the output terminal of the alternator, and where it goes into the fusible link box on the coolant recovery tank. Check the link, and the wire to the battery clamp. Looking for good solid connections. For reference & battery checking - Battery at rest readings - 12.0V = fully discharged, 12.6V = fully charged. Battery at rest means no loads or charging for at least 24 hours.

Solder side of ECU

Some address and data lines: EPROM CPU D0 11 37 D1 12 36 D2 13 35 D3 15 34 D4 16 33 D5 17 32 D6 18 31 D7 19 30 EPROM CPU A11 23 26 A10 21 27 A9 24 28 A8 25 29 I'm thinking these are high byte memory address lines. A0 of the EPROM goes to pin 9 of the LS373 8bit latch It's the Q4 output. I haven't found where the D4 input is. The damn conformal coating makes tracing by ohmmeter difficult. I may just start removing more ICs.

Here is another data sheet reference I just found. Memory pinout on pdf page 42. http://bitsavers.informatik.uni-stuttgart.de/pdf/hitachi/_dataBooks/1982_Hitachi_Full_Line_Condensed_Catalog.pdf I'll post a picture of the bottom side soon.

Yes, the sheet I uploaded seems to indicate single chip mode too. Maybe the EPROM is all tables?

Depending on which data sheet I look at, I see also that pins 4 & 5 may select modes. The smaller data sheet I posted the part number matches 100%. The big one covers many more ? or slightly different? ones. I just rechecked the 3 pins, 8,9,10 and yes, they are tied high by 1.00K resistors. 4 & 5 measure 4-6K to either VCC or GND, so I'll have todo some sort of powered up test to determine them.

Hard to be 100% sure with so little info, but plan on replacing the head gaskets. Over normal temperature while low on coolant almost always causes head gasket failure. Repeated, guarantees it. As long as it hasn't been really cooked bad, the reseal job should fix it. Miles on a decently maintained Subaru don't mean nearly as much to me as body condition.

P20 = pin 8 P21 = pin 9 P22 = pin 10 All 3 are tied high by 1.00K resistors. Pin 7 [standby NOT] is wired directly to +5V

ECU circuit board removed from case. EPROM removed from the board.

Might as well try it. If the puller is strong enough and the bearing isn't super tight, save a bunch of time.

I'll check those mode pins and look for the serial port first.

Why do this? Well, who knows what we may find? We can adjust and modify pretty much every other part, why not this one? Part of me always reads "no user serviceable parts inside" as a challenge, not a warning...

Wow! I'll download and check out those programs tomorrow. I don't see any connections on the ECU other than the external harness connectors, no secret ports. I can also read & burn & erase these EPROMS. When it gets far enough, I'll buy some. I'll install a socket in this ECU for the EPROM. I'll post pictures of the PCB tomorrow. [technically later today] I can trace out where at least some of the external sensor pins are wired, I have generated schematics from a number of circuit boards. The Big IC next to the CPU - I would not be surprised if it was a A to D / D to A converter or Analog I/O of some sort. There needs to be one, and there are a lot of analog circuity near it. The PCB looks like its only 2 layer. I still have the first computer I ever put together, an Apple II+ Actually ran it a couple years ago. I also have a Pentium that runs DOS and Win3.1 I've designed a few embedded controller systems, written a little code, but I'm not good enough at assembler to decipher this on my own.

Other ICs - Hitachi HD46520P 40pin DIP, right alongside of the processor. NEC D449C-1 24pin DIP along side of the EPROM. So far, I haven't been able to find any information on these 2. The 6301 history ideas above make sense to me. In the text HEX file, The leading :20 is ignored. using the first line as reference, the address is the next group of numbers, the 00 [first data byte] is 7F. Looks like 32 bytes per line.

I was hoping someone would have that sort of experience. I've written a tiny amount of assember code, some BASIC. I'm more of a hardware guy.

I was hoping someone would have that sort of experience. I've written a tiny amount of assember code, some BASIC. I'm more of a hardware guy.

The processor is 40 pin dip. I'll try looking up the other 2 good sized chips near the processor and EPROM. I'll have some time later today.

There is only 1 wire, because the normal situation is either pressure gauge OR oil light, not both. There is no reason to drain the oil pan, the sender is in the output pressure side of the pump. The oil in the pan cannot go uphill through a positive displacement pump to get out. Some oil in the channel will come out, but it's not a lot, and pretty much no way to avoid that.

Subaru GL Loyale ROM.txt This is a text file [hex] of the ROM I can send a .bin file of it, but apparently, not through the message board.