aftermarket ECU, M-REL, IGSW, how to connect?

[bk_]

I have an aftermarket ECU (does not matter which one, because no one knows much about it) that I'd like to connect to a 1JZ JZZ30/JZX90 engine. However I have opted with a custom-made direct harness instead of using the piggyback harness (impractical to install with zero room).

Unfortunately, the ECU was not designed to be used as standalone but rather in piggyback configuration, even though it's a full-control ECU.

Now I am stuck on a problem or two:
* ECU has IGSW input, BATT input, +B input, +B1 input.
* ECU does _not_ have M-REL output.

Right now I have (on engine loom side) IGSW and M-REL connected together. This means ISCV is never returned to full-open position on shutdown, since power to ISCV is removed once IGSW is OFF.

What is the generic way to connect aftermarket ECU to make M-REL and ISCV 100% functional with power-hold timer (set to 1 second - is this enough?), without M-REL specific output?

[RA35GT]

Mate, there's no point keeping power on the idle motor unless the ecu is programmed to open it on shutdown.

Check the manual for the ecu you have. (does it even have idle control?)

[bk_]

The ECU does:
1) have idle control.
2) does open it on shutdown. because it does work in piggyback configuration.
3) does _not_ have M-REL output.

Power is not provided to ISCV when "shutdown" is initiated, because this supplied from +B, which is controlled by M-REL... which M-REL output does not exist.

Why does it work with OEM ECU piggyback configuration? because the OEM ECU provides M-REL support (and everything else, except for ignition and injection output)

The manual wont help... because piggyback harness is only officially recommended. (dont ask me why)

[RA35GT]

Does it rely on the factory ecu (when piggy back) to open the idle valve on shutdown, or does it do it itself?

(i.e. Does it work if you separate m-rel and igsw and then manually keep power on m-rel for a few seconds while turning off igsw)

[bk_]

piggyback harness: OEM ECU controls ISCV, M-REL, fuel pump.
optionally, piggyback harness can be rewired to directly control ISCV, fuel pump, but not M-REL (since there is no M-REL output)

Some canadian guy who is assisting me and claims he has it working, could not describe or remember how he wired up M-REL, let alone describe what _changes_ he did.

[dumbass]

I recon on the plug in harness they join the ign and mrel wire together
I've done heaps of vipecs and to wire up the power to iscv when powering off is a pain in the butt,
And no std Toyota wiring is the same as how the vipec book tells u to hook up power to iscv when powering down
So I just join ign to mrel and u can still get idle motor to open up quickly on cold starts
Maybe some ecus can do it but vipecs and links need to be wired differently to std Toyota

[bk_]

I currently have M-REL wired together with IGSW... doesn't solve the problem as the aftermarket ECU operates like OEM - ISCV is open up on shutdown, rather than open up on startup.

if it did open up on startup, that would solve the problem of "forgetting stepper motor position".

[RA35GT]

If that's the case, I'd just make a delay circuit on the m-rel pin on shutdown

[jzk25]

I recon on the plug in harness they join the ign and mrel wire together
I've done heaps of vipecs and to wire up the power to iscv when powering off is a pain in the butt,
And no std Toyota wiring is the same as how the vipec book tells u to hook up power to iscv when powering down
So I just join ign to mrel and u can still get idle motor to open up quickly on cold starts
Maybe some ecus can do it but vipecs and links need to be wired differently to std Toyota

It's not that big a deal to wire up the Vipec hold power. Just an IGSW to DI and a diode on +B to IGSW. Works awesome. Stepper works shit without it.

[bk_]

IGSW to DI?

Anyway, for reference purposes here are the OEM diagrams. the "main relay control circuit" is what needs to be replicated.

Attachment 14801
Attachment 14802

[dumbass]

thanks jdk
i did run the ign to a dig input but didnt work to good
i didnt know about the diode on +b
i spoke to guys at link and they said it cant be done with factory relay wiring
ill try it next time i get one
going down to sydney for work and a big 40th next week so got nothing to test it till afew weeks

[bk_]

Problem is now resolved.

There were two problems:

1) I used the wrong external/custom-made powerhold (delay-off) circuit, because I assumed I could get away with not using an additional relay (wrong approach).

2) the ECU hardware, if maximum ISCV position is set to below 500, or minimum above 500, idle control "fails". In other words, if I set min=0 and max=125, it fails in a bizarre way. If I set min=375 and max=501, it's OK. A bug in the ECU firmware if I can call it that.