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Accessory ECU'S?

PDM Installation & Configuration

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Discussion and questions related to the course PDM Installation & Configuration

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I've understood the basics of wiring in my PDM unit, one problem I can't seem to get my head around is that I've got multiple "accessory" ecu around my car... a 1994 mr2 turbo to be exact.

Some of these smaller ecu's are labelled 'headlight retract', 'abs ecu', 'power steering pump ecu' and "door control ecu". How would I go about wiring these? I'm assuming for the headlight retractor motor I could completely delete the ecu and then use the pdm as some sort of trigger in conjunction with headlight stalk? This seems easy enough.

Now getting abit deeper into this, again I'm just assuming that the door control ecu locks and unlocks both doors at the same time when I turn the key in the door. Would I just wire a constant live from the pdm and delete the relay or fuse at the oem fusebox into this and leave the ecu as is or is there an even better way?

That's a lot. There is no one answer, every one of those will need to be wired in their own way.

What you need is the factory wiring service manual. That will tell you everything you need to know about how those work, and what you need to do with them.

And yes, some of them can probably be deleted, and the PDM can do the functions they perform.

The good news is that Toyota's wiring manuals are Excellent!

1994 Toyota MR2 Electrical Wiring Diagram Repair Manual | eBay

So in simple terms, some can be deleted and programmed via the PDM, and some I'd just provide power to like a fusebox?

Also, I'll be running a Link External E-Throttle Module alongside my Link ECU. When I watched the course he upped the amps on the ECU because it was using an H-Bridge for the E-throttle, Would i wire the e-throttle module separately and keep the ECU amps lower? I'm assuming he is referring to an on-board e throttle module and not external as mine need a separate power output from the PDM.

And just another one while the post is up, would I wire things such as headlights and fans together or separately? For example, I have two fans for my radiator would I use the same 12v wire and PDM output for these or two separate wires and inputs?

Same situation with the headlights would i wire both low beams together on a single output and the same with the high beam? this is my thinking of how it works so i can control these two bults seperately for both headlights.

There can be many ways to wire things up that will all work.

The best way for you really depends on balancing your needs against your limitations.

Whether you wire things separately or together usually depends on how many outputs you have vs how many you need. If you have enough outputs to wire everything independently, then that's usually the best way. But if you're limited on outputs, then you have to make a choice as to what things you want to combine together.

Example: You can wire two fans together, and that will work perfectly fine (as long as its under the current limit). But if one fan dies and overloads the circuit, then you lose both fans. But if you wire them separately and one dies, the other will keep working.

That's very true I never thought about dual redundancy capability. one last question that the PDM course didn't go over is how most people physically wire them into the car.

For example, a fusebox has a main power wire from the battery into the fusebox and then it branches off to various systems nearby (Battery > Fusebox > Individual Systems). I'm assuming with a PDM I'd have a lot of wire coming straight from the PDM to individual systems (Battery > PDM > Individual Systems) and possibly some things that just require 12v could run from a single wire at the PDM and then branch off (Battery > PDM > Wire > Multiple Systems), to keep the loom smaller? (E.G Radio, Interior Lights, Power Windows, Power Locks)?