I'm finally getting around to wiring up my Maxxecu Race (da Maxxecu Race wiring guide) and the only real issue that I'm running into that there doesn't seem to be great documentation for the alternator control wiring. Maxxecu only discusses setting up the output here, nothing regarding the wiring. Additionally, I've got no prior experience wiring in an ECU other than simple stuff involving my old MS2PNP, so needless to say this is a good bit out of my expertise. It is a good learning experience though that's for sure. Depending on help that I may or may not get here, I plan on emailing Maxxecu themselves for clarification, but they tend to be hit or miss in terms of communication. I'm not sure if I can bring myself to use Facebook to ask for help yet lol

Regardless, looking at the stock wiring diagrams found (here and here) it shows there are two pins that connect the stock ecu to the Alternator: The Alternator Field Terminal (Pin 1O) and the Alternator Feedback (Pin 1T). I'm confident that the Alternator Field Terminal needs to be connected to one of the Maxxecu's PWM outputs. What do I need to do to the alternator feedback pin, though? I'm under the impression this is a 12V signal that is intended to be fed back into the ECU so that it can regulator the voltage through the Field Terminal/PWM. There are not any 12V Inputs on the Maxxecu Race (unless I am missing something, which is fairly possible). So, I'm assuming that the Maxxecu intends on just using the voltage supplied to it through the 12V power to as the voltage input instead of using the feedback wire. If this is indeed the case, is it safe to just ignore the stock wiring harness's Alternator feed back pin?

Sorry if this is a dumb question, I just don't want to fry my new $1900 ECU package due to ignorance regarding the Alternator functionality. I've not read of anyone using a Maxxecu on this forum, so this might be out of place, but even if your experience is from another ECU brand, I'd still like to hear it.

 

I could be way off path here, but on Speeduino I remember they had a standalone alternator control circuit board (https://speedyefi.com/product/99-05-...control-board/) which is out of stock of course.

Iirc some people would go to a simpler NA alternator which are apparently easier to control.

Both of the plug and play ecus I've had have had the alternator control built in so I've never had to fiddle with it too much. Excited to see the build progress!

 

While these are two options, I was really hoping to keep the NB alternator and use the ECU to control it. Everything I need is there, I just need to figure out how to utilize it. I should’ve specified that within the original post.

If the ECU ends up having poor alternator control, then at that point I’d consider the NA alternator since it is internally regulated. But I hope I can avoid that.

 

Dunno if this helps, but on Link's NB1 pnp, one of those goes to an aux output at 1O, assigned as alternator control, which is a PWM output specific to alternator control.

The other alt pin at 1T says "nc", or no connection, but it's called "alt voltage". I'm guessing like you said, it uses this pin to regulate it's output on 1O in a factory ECU, but with a standalone you wouldn't need that. Internal battery voltage comes from other B+ inputs.

there's also 1Q involved BTW, which is labeled "charge light", which is a ground output when battery voltage is below 13v. You could pick any parameter here, they just picked voltage, less than, and 13v for their basemap, so don't forget to wire that in your setup if you're using a factory dash.

 

Yeah, I found this Reddit thread which also states the same thing as what you said, but it is regarding a non-PNP MS3. They also mention using a 1k Ohm pull up resistor connected to the sensor 5V source to get it to work with their ECU. I'm now trying to figure out if I need to **** with a pull up resistor or not. For example, PIN 8 on all MaxxECUs has a software configurable 660 Ohm pull up resistor where you can select 5V or 12V, but MaxxECU by default uses this for the tachometer. I'm not sure if this is for a reason, nor do I know if any other pins have this capability on the Race model. I'm waiting to join a facebook group to try and ask others for an answer before I email MaxxECU themselves. With it being a Holiday weekend, I expect the responses to take even longer...

 

I ended up using a 1200 Ohm pull up resistor, Inverted output control, and the default/example Maxxecu PID settings to get a solid idle. I’ve not been able to test it under varying rpm’s yet, but once I get the car driving I’ll try to update this thread in case it helps anyone else in the future.

 

Hello, Does it work with varying rmp's? I,ll have maxxecu too and need to wire alternator control.