The info I have are from documents in PDF format. Here's the links to the documents:
http://www.dodge-srt4.com/howto.shtml
(Mopar Stage 2 Turbo Toys Instructions)
(page 4 has wiring diagram for the toys)
http://www.dodge-srt4.com/tech.shtml
(PL Body Service Manual)
(pg 8W 30-26 has wastegate wiring info)
I've been hearing from other SRT-4 owners that also looked at what I'm trying to do. A couple are trying to do the same thing (HOM activation) with diff parts and components and ideas. For example, heres a copy of a comment from another SRT-4 owner after he had read about my Aquamist WI & HOM activation plans that I posted on the SRT-4 forums:
"Very nice. I take it that the yellow line is a momentary ground. Hard to tell. This was the problem I ran into. The ECU does not like constant ground. Very interesting."
I then replied with:
"I think I understand what you mean. The ECU needs to be able to override this. The DDS3 after making checks will activate the switch with a pulse. Even if the DDS3 say's things are good, the ECU can still say no."
To which he replied:
"What I had problems with was that pin C14 (white wire on HO Switch) need a 1 second pulse to ground to activate HOM one to deactivate... re-set so fourth. So with the varables in mind how do I educate my controler as to what state HOM is in. Ground side of the blinky red diode is good before the resistor. But no... There was a reson the red LED was a bad idea on either side. I can't remember what I found but I think it was voltage leaking from the ECU... Anyway
I started playing with the photocell side of a 12V Bolinger fiber optic tranciever. It knew when the light was out. It knew when it was on, and even better it knew when it was blinking... Then I lost intrest.
Please post what you come up with. I havn't abandoned my little bag of radioshake parts yet.
What is real nice is the use of a flowmeter rather that a pressure switch to see if fluid is moving."
So from reading peoples comments I'm a little lost.... taking everything perceived away and starting at square one.
From what I understand how HOM should work (NO WI, or DDS3):
You add race gas and then you hit the HOM switch and then run the car. The PCM/ECU sees the HOM has been activated and switches to an enhanced timing MAP or it just plain allows more timing based on HOM switch activation (more power). While in HOM mode the PCM lights up a Red LED to inform the driver of HOM activation. IF the driver activates HOM without race gas the red LED still lights up but... if after getting into the gas pedal the PCM receives a signal from the knock sensor that is not within the defined threshold of the HOM map it reverts to the base map (or reduced timing) and flashes the red LED informing the driver, hey you hit the HOM switch but you don?t have race gas in the tank, not going to allow this, possible engine damage.
The ideal scenario with WI:
The DDS3 makes the WI checks and activates HOM via sending a signal to the PCM just as if the switch was hit. The PCM activates the HOM map and lights up the red led. The DDS3 see that WI is still working fine. The driver gets into the gas pedal and because the WI has been setup and tuned correctly the red LED stay lit and the car has more power.
The problem scenario with WI #1):
The DDS3 makes the WI checks and activates HOM via sending a signal to the PCM just as if the switch was hit. The PCM activates the HOM map and lights up the red LED. The driver gets into the gas pedal and because the WI has NOT been tuned correctly the PCM reverts back to the non HOM map and blinks the red LED. The DDS3 does not care about the blinking red LED and continues to work even if HOM light blinks. The driver sees the HOM LED blinking and notices that the DDS3 is fine and realizes the tune is off. This IS NOT A WI failure problem it?s a tuning problem. To me this is how it should be.
The problem scenario with WI #2):
The DDS3 makes the WI checks and activates HOM via sending a signal to the PCM just as if the switch was hit. The PCM activates the HOM map and lights up the red LED. The driver gets into the gas pedal?shortly after the DDS3 sees WI failure?dumps boost and stops WI. Because WI fails PCM sees knock sensor reading above threshold ?.reverts MAP?red LED blinks. Driver either first sees DDS3 warnings or red LED either way doesn?t really matter since both systems have fail safes not dependant on driver action. Because the driver sees the DDS3 has found a failure in the WI he knows to look into the WI system. Again, to me this is how it should be.
The problem scenario, with WI #3):
The DDS3 makes the WI checks and something fails. Because of WI failure DDS3 never activates HOM, and PCM never lights up the red LED because the DDS3 never activated HOM. Again, to me this is how it should be.
OK, now why does the DDS3 need to know if PCM makes the red LED blink? If the DDS3 does not see a problem with WI, WI functions as designed. Just because the PCM say?s?hey you got no race gas in the tank, why does the DDS3 need to know, why should it care? The DDS3 does have control over a boost solenoid and will allow raised boost, this raised boost level will not be so much so, that without HOM working it will be dangerous. I always intended to tune the car first without any dependencies of WI for safety. The PCM will revert map regardless of whether WI works or not, IF it sees a knock threshold above HOM values.
I?m thinking that if the DDS3 can activate the HOM switch (turn on) then the DDS3?s HOM turn off capabilities is not necessary because the PCM takes care of that based on knock threshold values in the PCM. To me this is a fail safe that does not need to be messed with or enhanced in any manner.
IMO the answer is having the DDS3 just send a momentary pulse to the PCM. This pulse would be a mimic of the pulse of the switch when activated by hand. I must first say, that maybe I just don?t understand some basic electronics and this is not possible without also tying into the red LED so as to complete some type of circuit. I see the HOM activation by the DDS3 as a turn it on and forget it type of thing. Let the PCM via the Knock sensor say keep HOM on or turn it off because some parameter has not been successfully met. If I can, I would like for the DDS3 to turn HOM on and not care if red LED blinks. The proper function and control of the red LED by the PCM can be one of my tuning tools for WI.
Thanks
Jack