The SRT6 manual say's that the I/C pump is operated by a pulse voltage from a control module. I'm a licensed electrican and also have a degree in electronic's. I pulse voltage to me means that it would be like a square wave form, this inverted with a line across the top ( l_l l_l ), used mainly in speed control applications. Does anybody know what they are talking about? I have a hard time believing that the pump is variable speed. I'm wanting to tap into the pump curcuit to get it to run anytime I turn my aftercooler fans on.

 

I believe what you are referring to is Pulse Width Modulation. However, "pulse voltage" does not mean anything to me and I went through four years of electrical engineering training with formal power and analog electronics training. That term sounds like wrench-jargon to me and does not necessarily indicate a PWM circuit. In any case, a PWM motor could still be a straight-up DC motor, so if you hook up 12VDC to it, it should still turn.

There are only a few motor types that require any kind of modulated voltage to operate. The most likely are switched reluctance and stepper/servomotors. Now, I don't know anything about the motor that's in the IC pump, but I do know that stepper/servomotors would be a very expensive thing to have driving a pump. Switched reluctance motors can be identified by measuring the inductance of the motor as the shaft is rotated. The reluctance motor would have a big change in inductance as it is rotated.

Finally, the last possibility is that the IC pump motor is 3-phase. I'm not sure that's likely either.

Hopefully someone else will have more insight.

 

Well, the Johnson pump works the same when replacing OEM IC Pump. The Johnson pump is a 12VDC motor. So any 12VDC should run the stock pump fine. If you are going for better cooling... change out for the Johnson pump. It's smaller and just as quiet. I had to put my hand on mine to know it was running with the engine running.

Hope that helps.

 

Thanks Jody, I just have a two year degree that took me three year's to get going to school at night while working 55 to 60 hours a week. So I'm not really the sharpest knife in the drawer when it comes to complex electronic's, I make a lot better electrican . Do you think there would be any back feed problem to the control module if a guy just tapped into the hot wire down by the pump? Since it say's a "control module" there is most likely not an external relay.

 

Most likely there is a solid state 'relay' in the module. i.e. - Transistor switched power source. There may be a real relay too for all I know. What you could do to protect the module is use the existing feed to the OEM pump to switch a relay for the fans and the pump and run your own hot circuit. That would probably be my first choice as it would allow you to fuse the circuit as you see fit and keep the OEM module from over amping.

Cheers!

 

I've not actually looked for a pump relay yet, I was just going off what the SRT service manual say's. My fans are hooked up to a remote control relay controlled by a key fob and the relay is rated at 15 amps. I used a 15 amp fuse for the relay, the fans pull around 12 amps. I had turned them on & off countless times with the car not running (12.4 volts), but when I started the car and turned them on for the first time it blew the 15 amp fuse. It took me a while to figure that one out, with the car running you have 14.4 volts and the basic rule volts goes up amps go down. I finally figured out the it was either the inductive reactance of the relay coil or a resistor across the coil itself when adding a higher voltage caused more in-rush current when starting the fans. I was probably on the border line of blowing the 15 amp fuse at 12.4 volts. I could turn the fans on then start the car and the 15 amp fuse would hold fine. What you are saying is what I was intending to do, tap off the output of my remote relay and run it to the pump relay coil so that I wouldn't be pulling more amps on my fan relay & using the existing pump curcuit, that is if there is an actual pump relay somewhere.

 

Maybe a stepper motor?

 

The more I read in the repair manual the more confused I get. One section talks about shorting pin 34 of the connector and measuring the voltage on fuse #13 and goes on to say if the voltage is above 10 volts....... Something is telling me that the OEM system is not sending a full 12 volts to the pump at all times when it is running. I'm thinking I'm going to end up installing a double pole double throw relay in there opertated by my remote relay to keep OEM on one side of the relay & fans/pump on the other to keep things seperated. But I'm a little conserned about running a constant 12 or really 14 volts to it.

 

Steve,

When my SRT sat on the dyno (engine shut down), they would leave the ignition in the "on" pos.

Concerned - I asked why - I was told that whenever the key is on, the IC pump is running (regardless of temps) - thus coolant was circulating through the HE and the big fan they set up in front of the car was helping to cool the SC. (kind of like your idea) I have not tested this or know if it is true, but you could test that out easily.

I'm sure you could just tap off the + pump voltage wire to signal your new fan relay (I am assuming you are using a new isolated power source for your fans) then just click your key fob remote to turn the fans on and off.

 

Well if the pump is on anytime the key is on I have no need to do anything. I had spoke with HDDP a few weeks ago and had asked him if he knew what told the pump to turn on, I figured it was controlled by tempeture. HDDP said he thought that the only time the pump ran was when the supercharger was engauged, but I don't think he was 100% sure. I hope what you said was right, in the repair manual the voltage runs through fuse #13 under the hood and the way I understood it, there was no power to that fuse until the control module sent it there. And on the fans I installed, they are on their own circuit and the relay is built in with the reciever. My main goal was to have the coolant circulating while the fans were on, so if the pump runs anytime the key is on I'm OK . I'll have to do a little testing, but while I had the front of my car off (car running) I didn't think the pump was running, at least I couldn't hear it or feel a vibration of any kind.
I do know that there is a fan the the box that houses the ECU and it runs anytime the key is on.

 

Problem solved, I called the experts, RENNtech. The pump does run anytime the key is in the on position.

 

I just went threw this with my dealer. Chrysler says "key on - pump on". Chrysler is wrong, Rentech is correct. The second tech at the second dealer that worked on the car figured it out. The first dealer replaced an PCM, pulse module and a fuse box becuase corperate Chrysler gave them bad info, good thing it was warranty work. It was a lot of frustration.

 

Good news Steve, Keep up the good work and let us know how it turns out.

And it's some good 411 for taking the SRT to the track - you can help cool your SC down by leaving the key on. Especially if you have installed a big Coolant tank with Dry Ice racks. (and installed fans like you)

A little more boost for the hole shot.........

 

Yeah, the aftercooler fans & Hoosier D.O.T. DR's should improve the performance at the track BIG time. I never did get my car to the track last year, one reason is I knew I wouldn't be able to get off a good launch with the traction problems I have, now you understand what I mean about traction problems . I still have one big problem, there's no 1/4 mile tracks within 100 miles of where I live, just the little 1/8th about 15 miles away. So I'm either going to have to invest in a car hauler or get the wife to follow me with a jack & the DR's in her Envoy or my truck. On the fan deal one of the reasons I didn't think the pump was running was the fact that it dropped the aftercooler temp's 14 degree's in two minute's after getting the temp's up & turning the fans on. Cooling it that fast I thought it had to be just cooling what was sitting in the core.

 

It is refreshing to see all the engineers here, I am also a Dilbert and even know why scott adams made Dilberts tie flip up.

Youll find it interesting to note that the main radiator cooling fan has its speed controlled as determined by the engine temperature. I measured this on my srt in the garage and used a digital meter, though I believe that the power was modulated by a PWM controller. Woody

 

Well, as a non-electronic old school mechanic I can say the following. My Intercooler pump went at 18,000 miles. It seems the impeller bearing went belly up so there was a distinct "whine" from the pump. The next morning, from cold start through the 15 miles to the dealer where it was replaced ( free ) the whine was constant with no change in pitch to indicate variable speed or voltage just a constant harmonic whine. So my observation would be that the pump must be running when the key is on, unless of course I'm missing something here.

 

The term "Pulse Voltage" came right out of the SRT 6 tech manual, since this thread was stated I've done a little more research about when the pump runs. Here is the link, the pump does recieve full voltage when it's running - https://www.crossfireforum.org/forum...ad.php?t=23500