AEM and the Alternator Field Signals

[TurfBurn]

I didn't feel like wading through that huge pile of a thread that got out of hand on the AEM... but here's my question. How is the AEM dealing with the alternator issues on our cars.

I have a microtech which requires a swapped alternator. I finally found out the why and how behind that and here it is:

"I pulled out the factory manual on the 02 protege and I see where the alternator is working in relationship with the IAC and spark control. With the Microtech in place it looks like the alternator is no longer recieveing the field signal to make it come on line and charge. So maybe what they did was install a different internal regulator and diode pak to make it work from a key on power source."

- Basically what I need to figure out how to do if it is easy for other people to use this system, or what AEM has to have hurdled. (TurfBurn)-

AND

"I have checked this out and the 01 on up Alternator is definatly different than the 90-00. So to make it charge correctly you can change up to a earlier alternator and then use a ignition on positive wire to energise the feild or you can have your current alternator modded for about 100 bucks but you still have to change the field wire to ignition on positive. So which ever is better for you .."

Those are quotes from maxrotor on the microtechfiusa.com forums.

So then my question is if the AEM is providing this field signal for the alternator to get it to come online and provide the charge necessary for keeping the battery up and the systems all happy and dandy, or is that still a hurdle that is being attempted?

Does anyone know enough about alternator field signal to know what it needs? If I knew what it was expecting I could rather easily build something up most likely to do that... Basically set it up so that when the car is being "run" that the field signal is provided and the alternator would then charge. In other words I don't know the workings of an alternator enough to figure this out, but if someone does that'd be awesome. I'm assuming the AEM unit takes care of this, so hence my linking it to that!

Thanks all!

Steve

 

[low_psi]

Well right now they are working on the AEM in parallel mode, not full stand alone. I don't think they have wired the AEM as a standalone yet in their developmental testings. THerefore I doubt they can answer you, because the alternator won't become an issue until the unit runs as a stand alone.

 

[TurfBurn]

Well actually the microtech runs in parallel as well. But as it indicates in the quotes above that once you start doing the ignition system you get mixed in with the the ECU and how it interfaced with the ignition and the alternator and becomes/became a problem. I'm assuming even in parallel the AEM will have the same problem as the Microtech. Hence my interest in their work around as well as the possibility of creating a similar work around for the microtech.

 

[perfworks]

Turf and Mx3,

The AEM has been and does run in both standalone and parallel modes. We have not released it on this forum for another issue all together. It works flawlessly though and I couldn't be happier with the results.
I am well aware of the alternator and tach problem associated with the EECV datastream. I will see if I can help you. Pm me and we can talk.
The problem from what I understand with the microtech is the amount of configurable auxillary outputs available to the enduser. The AEM has 38. So there are plenty of ways to get things assigned. Also we are in the process of getting the Tach done also. So if I can help you on your way I will.

 

[TurfBurn]

Excellent! Very much appreciated. I'll probably pm you at some point to get some info! Good luck with the AEM. And damn... 38 outputs is a lot!

 

[TurfBurn]

BTW.. is the Haltech unit and some of the other's as well just using auxillary outs to overcome the alternator as well? or what up!

Just seems nuts to me that this problem exists and that everything else solved it easy or so forth but the microtech would have such a block. It may be the case, but frankly I vastly doubt it!

 

[ddogg777]

Hey Steve,

Not all of us who have the AEM are without this problem. My alternator light has always been on and just this past few days has given up charging the battery (though I think it was charging before because the voltage was higher when the car was running, about 13.4V). I'm not sure why it was working for a couple of weeks and now it doesn't, but any help would be appreciated. I've heard that some who have the AEM installed don't have this problem but others do, so something in our setups must be different and I need to find out what...
Any ideas?

 

[TurfBurn]

Yeah.. I have all sorts of ideas as we saw all of the above with the Microtech....

You were definitely charging if you saw any voltage above 11.8 when the car was on...

You need to make sure the car has a fake IAT signal if nothing else (1.2K resistor works) and the stock ECU needs to see the crank signal... make sure those two things are okay and it should solve the charge issue... any problems with your tach at all? or is that being run by the AEM?

 

[ddogg777]

The IAT is still hooked up but the MAF is not, does it have to be connected too? The AEM is sharing the crank signal (diodes) but I have noticed that the stock tacho flips out at about 6000rpm and instantly drops down like the car had been shut off (car is still running fine though) until I let off the gas and drop the real rpms down, then the tach registers normal again.
If nothing else, perhaps I did have a bad alternator. The funny thing is is that we swapped out my stocker because it wasn't working and swapped in a used one, perhaps it was bad too. I mean, usually the idle voltage is like 14.4V, not 13.5V, right? But before I throw down $160 for a new alternator, I want to make sure it's not something simple.
I consider you the knowledge base of all the stock electrical dependencies because I've seen how you like to understand the ecu and its properties.

 

[TurfBurn]

You won't need the MAF... it does sound like the way you guys are clipping the CAS is causing problems... we have found that alternator issues often are indicated by the tach.. but it does sound like your alternator could also be bad... 13.5 is pretty normal for idle... even 13.1 is relatively normal at idle..

If you are going to replace the alternator I would almost recommend just getting a used junkyard 1996 626 alternator with the right pulley grooves... then a minor tweak to the wiring for that and it cuts the stock ECU out of the picture and you'll have a closed loop alternator system independent of the ECU.

 

[ddogg777]

Hmm, I think maybe the problem lies in the fact that the stock ecu is not seeing any TPS voltage (it's completely used by the AEM). I read that it is a constituent, what do you think?

BTW, where do I read up on the 626 alternator mod?
Here I go searching...

 

[TurfBurn]

TPS doesnt affect the alternator... I know you can steal that signal completely without issue.. only cam and crank every really had any major affect on it..

I think I mention the 626 stuff needed in my MP3 rebuild thread.

 

[CWiLL]

i have had no problem on starting the car or having dead battries. the car does idle low voltage (like 12.7) but i have a crap battery in it. aem seems to allow mine to charge. im not sure how.

 

[ddogg777]

Chris, I think my IAT is unshared with the stock computer and is causing my battery light, how bout yours?

 

[ddogg777]

Steve, is it possible that the alternator doesn't always get shut off by the stock ecu? I find it difficult to believe that I have two faulty alternators. I guess the best way to be sure is to tap the IAT line back to the stock ecu and see what happens...this weekend's project..

 

[TurfBurn]

It's a complex interelated system so without knowing exactly how you guys are sharing signals here and there it is hard for me to say what is exactly causing it... the alternators are really sensitive and you'll take them out easily if you try starting the car with a battery charger/start assist attached or so forth.... I've had sponsored guys blow them a number of times.

Thanks!

steve

 

[ddogg777]

This is all I have done:
PINOUT

AEM plug: Stock harness:
A2 - Switched ground (output) MIL 2 (to get rid of MIL)
A16 - Fuel pump relay (output) 80
A20 - Radiator fan (output) 47
B1 - Sensor ground (output) IAC ground 83
B1 - 12V switched (input) 71 or 97
B2 - Ground (input) 24 or 51 or 76 or 77
B4 - Injector #3 (output) 101
B5 - Injector #4 (output) 74
B11 - Injector #1 (output) 75
B13 - Coil #1 (output) 26
B21 - Constant 12v (input) 4 (shared)
B23 - IAC valve (ouput) + 54
C3 - Knock sensor (input) 57
C7 - Sensor ground (output) knock ground 59
C8 - Crank sensor + (input) 21 with diode (shared with ECU)
C9 - Crank sensor - (output) 22 with diode (shared with ECU)
C12 - Coil #2 (output) 52
C16 - O2 sensor lambda (input) white wire on AEM gauge
C25 - AIT (input) 39 (edit: now shared! yay!!)
C26 - Engine coolant temp (input) 38 (shared with ECU)
C27 - TPS (input) 89
C29 - Cam position + (input) 85
C30 - Cam position - (output) 86
D1 - Injector #5 (#2) (output) 100

My AIT is not shared so I think that may be why I have the generator light on. Other than that, I don't see what effects the AEM can have on the alternator...

 

[ddogg777]

Woot woot! I fixed the problem (AIT not connected to stocker) and now the battery light is off and I measured the idle voltage at 14.39V, perfect! Thanks for your help Steve!

 

[TurfBurn]

Great to hear! Now lay down that power.. I need numbers to shoot for with my setup .

 

[Jeph]

Ok, to stir up an old thread, i think i am having some of the same problems as ddogg was having with the battery light on, and my voltage fluctuating ALOT. I can't seem to find any other info about making the alternator standalone from the ecu, so that could be a starting point.

My tach is also not working at the moment, so any light you can shed on this would be great steve.

Jeff