TOD discussion

[mbeach]

O.K., this is a bit unrehearsed.

This was the cable that I built to interface to the TOD:
[img]
http://www.vehicross.info/gallery/data/500/thumbs/P2130001.JPG[/img]

This was the cable map, it shows what parameters were monitored:


Here is the TOD connector:
[img]
http://www.vehicross.info/gallery/data/500/thumbs/TODview.JPG[/img]
I spliced into this with my cable. Connections were made inside of the plugs (which are impossible to dismantle by the way. If anyone knows how to take these things apart, please let me know. I was forced to solder INSIDE of the holes underneath the white clips.)

TOD interface cable, ready to go.

Here's the road we used for testing. Old Murphy Dome Rd., about 18 miles north of Fairbanks, Alaska. This road starts out as packed gravel, frozen with patches of hard snow and ice. It quickly peters out into a narrow trail, all ruts and deep snow, about 5 feet wide. Yes, I scratched the truck -a lot.


This is my lovely co-driver, whose patience was sorely tested this day. "...I said SPIN the tires woman!"




This is a scope shot taken at idle, in Neutral (transmission). Notice the pulse width.

At 60mph (on ice) in 15% mode:

Random scope shot:

I need to attach an .xls file. how do I do this?

[mbeach]

I have it on pdf now and still can't attach it to the post. What gives?

Here's a caption for the file if I can ever upload it.
"If there's a blank, it was not important enough to fill in. I chose not to mess with the ABS leads after I determined that it had no effect on the TOD. I'm sure that the TOD uses the ABS as an input, but the 4WD Out to the ABS is unreadable.
TPS signal is variable via potentiometer at the throttle. Roughly 0-13V.
The VSSs are weird Hall-effect sensors operating at 4-5V.
The indicators work as explained in the maintenance CD. Switched grounds indicate an "on" state."

[VehiGAZ]

You soldering fool! WOW mbeach - you have gone above and beyond the call here! I am truly impressed by what you have done to get this nut cracked.

As for the Excel file, there is a size limit on attachable files, which I ran into when trying to post the ToD patent file. Moncha PM'd me about it, but of course I deleted the PM so I can't tell you what the limit is. But if you have just a data spreadsheet, it shouldn't be running into the size limit. Alternatively, you can try to post it in the Downloads section of the site, but I didn't have much luck with that, either. It seemed to want a URL for the file - I wasn't sure.

So although I absolutely LOATHE drawing conclusions or even being guided in my research by initial data, don't your findings suggest that we shouldn't send a static 68%+ signal to the clutch? That is, wouldn't it potentially be too much when you are accelerating from a stop? Or no?

The difficulties with the wiring harness shouldn't be a big deal. If we just need to tap into one wire (the one going to the ToD clutch), it's just not worth rigging up a dedicated connector. Of course, judging by what you've done already in the cable-making department, I realize you may not agree with me :-). It can still be a simple install to cut the clutch wire and splice in the switchable circuit.

Ok, good luck with the data interpretation! Let us know what else you figure out!

[mbeach]

Having the correct plug (we only need one of the two) would make life much easier, and it would look nicer.

As far as I can tell, we only need to cut/intercept 1 wire. The pink TOD to solenoid wire. We will want to 'tap in to' 4 more wires, each for the 3 display segments and one for the AUTO display.

That's 4 taps and one cut. Not too bad, even for a novice. We just have to make sure that everyone uses high-quality taps (if there really is such a thing). Vibration is the enemy of the wire tap (scotch-loc, et al.).

As for the 68% duty cycle for 4wd.
This is a bare minimum number, and at high speed may not be high enough.
The purpose here is not to replace the TOD's logic, we are just trying to modify its outputs. There really is no such thing as overkill as long as we provide a nice 50Hz pulsed signal to the e-clutch.
I say 87-88% duty cycle would work for just about everyone, regardless of battery juice available.

The biggest surprise for me was the presence of voltage at the pink wire when in '2wd'.

[VehiGAZ]

I think you're right - a decent margin above 68% will probably do the trick nicely - and if it's not enough to maintain full 4WD-Hi at 60 mph, well, you probably don't really need 4WD in that case anyway.

So, uh, are you going to throw a circuit together, mbeach? And post required parts and directions? Pretty please? Winter's coming here in Connecticut... :-)

[mbeach]

I'll try to work on this today. I have a lot of parts available to me that may not be readily accessable for most people.
Today I found a really nice trimmer that would make a cool knob. Very tactile with nice feedback. It felt like a BMW iDrive unit. It could be easily replaced with a 2k ohm potentiometer from Radio Shack though.
I'm trying to make it as simple as possible for everyone to build/commission to build.

Reality is, all we did here was to confirm the work that the Terracan guys did. I never was able to look at the links, but from Bob's first post, it sounds like we have just done our own version of the same thing.
I can't take any credit for this, but I assure you that a VX ready solution will be on the way asap.
I'd still like to share my spreadsheet, but I think that we can get started without it.

[mbeach]

It appears that there is a mass-produced PWM controller that will suit our needs. All we need now is a pot, a knob, and the ability to ground the indicator lights at will. This can be done through the same pot(entiometer) that selects the 4wd mode.

It's getting easier and cheaper by the day.