Fireman438

No sweat. I'm fairly decent at figuring out electrical and wiring. Not knowing the inputs Ford uses to drive it is what I'm looking for. Before i go any further, what is the function of the SCP bus network. it sounds like it is information from a variety of sources going to the different gages. If I tap into that @ the PCM, first: how will the cluster know what signal it's getting so it can be routed appropriately, and second: do I use the SCP pos. wire for my crank sensor input?

And yes, pins 21 & 22 go to the crank sensor, and pin 85 is for the cam sensor. Pin 91 is a "signal, return", doesn't say returning from what.

One thing I did do was count the # of teeth on the crankshaft tone wheel on the V10 that came out and it has 40 teeth with a space for 2 more teeth, for the actual crank pos. sensing. The cam only has a single raised portion on it for cam pos. sensing.

Just as a final question, what is your background, if I may ask? You have quite a bit of knowledge regarding this stuff, and it's very helpful.

Thanks
Rich

Mo Smoke

I am a gear head and strive for perfection at everything I do that I want to do. (I don't want to sound like an ego thing) If I have the ability to figure it out I will, and it is more like a pride thing. the sig return is like a telephone line pair of wires, it is a balanced pair that returns to the pcm with that signal kind of like supply and return, some returns are ground referenced and may require you to t-tap into the supply line for a bias reference voltage to keep the pcm happy in processing the signal. I work on 2-way radios for my paying job and take care of many public safety municipalities so I pick this up pretty easy....not bad for just a highschool diploma huuh ?

Mo Smoke

Here is a quote from the 2002 service manual.

"Tachometer

Gasoline vehicles are equipped with a 6,000 rpm tachometer and diesel vehicles are equipped with a 4,500 rpm tachometer. The instrument cluster receives the tachometer data from the PCM via the SCP nework and commands the tachometer according to the data."

Crank sensor:


The crankshaft position (CKP) sensor is a magnetic transducer mounted on the engine block adjacent to a pulse wheel located on the crankshaft. By monitoring the crankshaft mounted pulse wheel, the CKP is the primary sensor for ignition information to the powertrain control module (PCM). The trigger wheel has a total of 35 teeth spaced 10 degrees apart with one empty space for a missing tooth. The 6.8L ten cylinder pulse wheel has 39 teeth spaced 9 degrees apart and one 9 degree empty space for a missing tooth. By monitoring the trigger wheel, the CKP indicates crankshaft position and speed information to the PCM. By monitoring the missing tooth, the CKP is also able to identify piston travel in order to synchronize the ignition system and provide a way of tracking the angular position of the crankshaft relative to fixed reference (Figure 25).

Fireman438

Sounds like you and I are cut from the same fabric. i have a background as a trained diesel mechanic, and i love the one-off projects. It's a great challenge and a continual learning process.

The pulse wheel i understand perfectly. And it sounds like I mis-counted the pulse wheel teeth. Also sounds like the pulse wheel is what the PCM reads for tach info., which makes me wonder if I can use the 4 pulse tone wheel that I was supplied, or if I need a 40 tooth (or 39,with the 1 missing, if that's what the PCM needs) to give the PCM the correct information.

Also, if the SCP Bus is a balanced pair, do I also need the tranny temp input (which i lost when i installed the PCS Tranny Control Unit) along with some sort of tach signal to allow the tach to work, or does the input signal just need to be balanced for each gage? I do have oil pressure, engine temp, charge voltage, and speedometer currently. Do those gages all run off of the SCP Bus circuit?

I'm also thinking that, since the PCM doesn't read an ignition pulse (like old-style tachs) and uses actual crankshaft speed, I can have a factory style pulse wheel made, just a larger diameter so that a factory-style signal can be generated. And, along those lines, does the cam pos. sensor factor in to tach signaling?

I've tried contacting all 3 local Ford dealerships for this kind of info, and I get the feeling that it's more than an inconvenience to make any sort effort to look up this info, so I appreciate all your time you're putting in to this. I've talked to a few people like yourself and other people, such as the good folks at PCS, and we all seem to be in the same boat. It all goes back to needing info from Ford, which they seem unwilling to privide, at least if you go into or call the dealership for info.

Mo Smoke

From what I can gather from the SCP bus it is just data with headers that tell each bit of info to go where it needs to be so if you do not have trand temp that faulty or default data will only show up there and a tach signal will have a header that will be directed to that particular address in the cpu and then will be displayed there. If I can get my hands on a gas jobber I will disconnect the crank sensor and see if the tach drops without killing the motor. The SCP only uses these on this bus:

engine coolant temp
engine rpm
trans temp
glowplug status (diesel only)Duh!
overdrive cancle status.

Fireman438

I got to thinking tonight at work depending on how the "clean tach output" is wired do you think that maybe it could be backfed, therefore using it as an input rather than an output without damaging the PCM, to at least see if it will run the tach in more or less a conventional manner?

Also, when i wired in the PCS tranny controller and lost the trans temp, i called them and asked about it. I was told that I can run the temp gage to the dash first, then to the controller, by switching pins on the controller plug.
Since the '02s have different wiring than the previous years, I'm wondering if i can t-tap in to the signal line for both the dash and trans controller, thereby sending a signal from the trans temp sensor to each of them at the same time without having to run through the dash first, and thereby simplifying the wiring and getting function from them both (the trans controller and the dash gage). I'll call PCS in the morning and see what they think, too.

Rich

Mo Smoke

I would think that the trans temp would work if it doesn't load the line down but you can see that by probing the feed to the dash and see what the reading is then add the pcs wire and look at the reading again and see if it loaded down.

Mo Smoke

I just got off the phone with Scott and he said Kai's truck used the Cam sensor input, but can't remember if they grounded one leg of the pickup or left it balanced.

Fireman438

I was just looking @ Kai's truck on Scott's website and I think i noticed that it was originally a PSD truck? If that were the case, can I still use the cam sensor from the gasser? Seems weird that the cam sensor would be used, but I don't know enough about what runs these newer, computer driven tachs. Also, did Scott use a 4 pulse tone wheel? doesn't seem like it would work, since not only does the cam turn half the speed of the crank, but you'd also be adding 4 extra pulses for the first crank revolution and 3 for the second (the gasser uses 1 pulse per cam revolution) thereby causing 7 extra pulses for each cam revolution.

What are your thoughts?

Fireman438

Kai's truck is also a CR engine, which requires a cam sensor to run the fuel injection. I am running a 12v, so I don't have that option. I have a ton of things going through my head, but it all boils down to what inputs are used to drive that dang tach.

Mo Smoke

I know Denny's truck was a PSD but not sure on Kai's, either way try it on each one of the inputs and we will both know...lol I will be around today if ya need help as I am wiring my PCS Controller for paddle shift using the cruise buttons for truck pulling....(Should be interesting) 603-620-3608 is my cell.

Tim

Fireman438

What time zone are you in? I'm pacific Standard.i'll be at a wedding this afternoon, but I'd love to talk to you about this at some point. my cell # is 509-251-5927.

dieselclam

Kai's was a 7.3 PSD.

Mo Smoke

So .....Did ya make any progress????

Fireman438

Nope, no progress yet. Between working swing shift, birthdays, trying to get the house put together after our recent move, looking for new beds, etc., it's been a very hectic few weeks. And, my in-laws will be in town this weekend, so guaranteed no progress this weekend either. Oh well, I'll get it done... eventually. At least I haven't cut any "unnecessary" wires yet, so there's still hope. And, even though I couldn't pull up the PDF files from the link, I got them from the e-mail you sent. Thanks, I think they'll be a big help.