Megasquirt Support Forum (MSEXTRA)

I've been trying to wrap my head around what spare outputs I have available, and how to make us of them.

I have the preassembled 3.57 PCB MSII unit, tethered to a diyautotune relay board for all of my wiring. The engine is running decent as is, but I have more to do.

I want to make all of the possible spare outputs available so they're ready to wire up to a component when I'm ready, so I think I'll put everything necessary in an external box, and wire through the DB15 connector.

IAC1..2 are already in use for my IAC.

Some of the things I know I'll want to control:
Boost
Electric cooling fans

The maybes:
Water Injection
EGR
EVAP Solenoid

...and whatever else I dream up.

Boost is my immediate concern, so I think I'll just use FIdle for that since it is already set to go and supports up to 1 amp

From my reading here:
http://www.megamanual.com/357/

TACHOUT AccellLED, and WarmupLED it seems I can just solder jumpers from PAD1..3 to the DB15 out PADs, and then build a circuit like so to make use of a large draw device:


IS it that simple?

Also, can I leave the surface LEDs alone and do this? They don't have to be removed?

It seems I can make use of SPR3 & SPR4 in the same way, but from what I've read on these two are already run to DB37, so you can splice into the cable if you want to use them. I'd rather just re-route them to the DB15 connector, and I'd likely want to do the same with SPR1 & SPR2 in the event I want to use CAN bus one day.

Yes it's that simple, but you should map out what you're going to use each output/input for because it can change the circuit required.
For example, depending what you consider a "large" draw, you might need to substitute the ZTX450 with a higher current transistor.

hybrid wrote:Yes it's that simple, but you should map out what you're going to use each output/input for because it can change the circuit required.
For example, depending what you consider a "large" draw, you might need to substitute the ZTX450 with a higher current transistor.

Is there any downside to building them all with ZTX450?

Yes, some things may need higher current. There are diagrams that use an irlz44 or tip120/122.

I'm a bit of a knuckledragger sometimes, so I apologize to all reading.

A few more things have become clear to me, please correct me if any of this is wrong:

SPR1 thru SPR4 are nothing more than PADs which route to the DB37 connector. Until you solder jumpers from somewhere else they don't do anything.

If I wish to make use of CAN, I'll have to solder jumpers from JS6, JS8 (for my purposes, it is probably best to run them to the DB15 PADs rather than SPR1&2, because I'm using the relay board and can't access those pins on the DB37 without splicing)

FIdle on the 3.57 PCB is already setup to drive something like a boost solenoid directly. In order to do this I should remove the relay from the relay board, and jump the spade slots so it can drive the device directly from the terminal block

In MS2, the only thing I can readily and easily setup for PWM is the boost control logic

This one is more of a question: The common reason you might build a circuit using something like a TIP122, is so you can drive a device directly without a relay using PWM; otherwise for "on/off" type circuits, a basic relay setup like the one above would suffice?

Lambo wrote: FIdle on the 3.57 PCB is already setup to drive something like a boost solenoid directly. In order to do this I should remove the relay from the relay board, and jump the spade slots so it can drive the device directly from the terminal block

It appears that perhaps I was wrong on this one, I guess I'll need this mod kit to make it work??
https://www.diyautotune.com/product/meg ... l-mod-kit/

Depends on the solenoid, I have used the little vw n75 boost valves with 3.57 fidle before. Higher current valves you will have to do some checking.

Lambo wrote:

hybrid wrote:Yes it's that simple, but you should map out what you're going to use each output/input for because it can change the circuit required.
For example, depending what you consider a "large" draw, you might need to substitute the ZTX450 with a higher current transistor.

Is there any downside to building them all with ZTX450?

Not the most reliable transistor ever, IMHO. 2N2222 (used within its limits) is better.

For PWM, rather than build a larger transistor circuit to drive the device, could you build one like schematic above with 2N2222, but substitute the mechanical relay with a SSR?

Lambo wrote:For PWM, rather than build a larger transistor circuit to drive the device, could you build one like schematic above with 2N2222, but substitute the mechanical relay with a SSR?

Yes.

There are configurations settings described in megamanual to configure it to "pull low" to ground, or produce 5V. That seems to no longer be relevant for msextra.

Do the PADs on 3.57 for Tach, ALED, WLED, PA0 etc simply just produce 5V now?