Shoeless
05-17-2020, 10:43 AM
Hey guys,
This was a fun one for me, but I somehow ended up getting the new Cadillac CTS-V Alternator even after taking copious notes a long while back telling me to get the older one. For anyone that was interested or read all the posts from a long while back, the newer one requires a PWM (Pulse Width Modulated) 5V signal operating at a variable duty cycle depending how much charge you want (67% cycle = 14 Volts), and at a set frequency. The older one simply requires a +12V switched signal.
So now I'm stuck with two options:
1. Sell it and buy the older style as I'm way out of the return period.
2. Find out a way to get my standalone ECU to crank out this signal.
I'm opting for option #2 before I go spend more money. I did tons of searching (Other forums and AEM Infinity FB Page) and a bunch of reading (400+ page ECU manual and supplemental documentation) and have found a solution with some input from others. So the AEM Infinity has two types of switching it controls (low side - switches to ground and high side - switches to 12V), but I need a 5V signal to start with. Thankfully there's a standard 5V power supply signal typically used for some sensor that I can use.
So now I have a 5V signal and a low side switch to bring the signal back to ground, but need an additional component, that's where a pull up resistor comes in. Here's what the circuit will look like
https://i.imgur.com/WNpiwjb.jpg
So this will now put a 0.05mA load on the 5V circuit (well within acceptable limits) and the lowside switch gets me to ground. Within the AEM software, I can set up a 2D table with duty cycle anywhere from 0-100 (Typical OFF and ON state) and frequency. I can even change the duty cycle based on engine RPM and have the alternator give more charge at lower RPM and less at Higher RPM.
Problem solved :cool:
This was a fun one for me, but I somehow ended up getting the new Cadillac CTS-V Alternator even after taking copious notes a long while back telling me to get the older one. For anyone that was interested or read all the posts from a long while back, the newer one requires a PWM (Pulse Width Modulated) 5V signal operating at a variable duty cycle depending how much charge you want (67% cycle = 14 Volts), and at a set frequency. The older one simply requires a +12V switched signal.
So now I'm stuck with two options:
1. Sell it and buy the older style as I'm way out of the return period.
2. Find out a way to get my standalone ECU to crank out this signal.
I'm opting for option #2 before I go spend more money. I did tons of searching (Other forums and AEM Infinity FB Page) and a bunch of reading (400+ page ECU manual and supplemental documentation) and have found a solution with some input from others. So the AEM Infinity has two types of switching it controls (low side - switches to ground and high side - switches to 12V), but I need a 5V signal to start with. Thankfully there's a standard 5V power supply signal typically used for some sensor that I can use.
So now I have a 5V signal and a low side switch to bring the signal back to ground, but need an additional component, that's where a pull up resistor comes in. Here's what the circuit will look like
https://i.imgur.com/WNpiwjb.jpg
So this will now put a 0.05mA load on the 5V circuit (well within acceptable limits) and the lowside switch gets me to ground. Within the AEM software, I can set up a 2D table with duty cycle anywhere from 0-100 (Typical OFF and ON state) and frequency. I can even change the duty cycle based on engine RPM and have the alternator give more charge at lower RPM and less at Higher RPM.
Problem solved :cool: