1st Gen Haltech ECU Discussion

So to recep:
VSS1 is the 3-wire (assumed hall sensor) that sits on the passenger side of transfer case on a 340F, and on the rear driver's side of a 340E. Feeds odometer, then odometer sends it into ECU for backup if VSS2 fails.
VSS2 is the 2-wire (reluctor sensor) that directly feeds only the ECU for automatic trans control and is used by default.

VSS1 is apparently what fed into the PnP harness from the get-go. When I swapped to an A340F, my harness no longer reached to the new spot of VSS1, so I had no odometer, and the Haltech didn't know my speed anymore (not that it uses it for anything by default).

My factory ECU trans control still worked because VSS2 still was plugged in.

Now what I've done is tap the VSS2 reluctor sensor into the Haltech where the VSS1 sensor from the ECU side was tapped in previously. Then I fed a new generic output into the VSS1 harness, which pulls down at a frequency proportional to the speed determined by the Haltech via VSS2. I now have my odometer back and I should be able to calibrate it however I like.

The issue is now that if VSS2 fails, there's no fallback for it, so I'll probably keep an extra in the truck. The trans also still does not recognize the calibration of the odometer, unless I fake a VSS2 failure, which is easily done by unplugging it, but leaving it plugged into the Haltech (in theory).

 

Ah okay, I always wondered how that part of the 4WD swap worked. Well sounds like you're well on your way to sorting the speedo out. I don't know if the Haltech can ever be fast enough for your ODO output but possibly. There's an internal filter level before the adjustable one we can set. They've changed the filter of certain inputs at a firmware level before.

 

Hmm that makes sense. Like I'll come to a stop and the reading will still be dropping from like 5mph for a couple seconds. I may end up just tapping the VSS1 too/instead

 

So evidently you cannot get any P/N switch reading without decoupling it from the starter relay. That sucks. Only alternative to getting "in gear" or not is porting in L,2,D, and R (4x what I'd hoped, but at least only D is a hassle).

 

Bit dead in here lately innit

 

See we're attacking the gear position thing different ways. I've just left it alone and set an offset for going into gear for the time being until we do trans control because then it'll already know. I didn't realize it would be so involved just to derive a gear position. I almost think it would have been easier for your setup to just use a linear position switch

 

The thing I'm curious about is how it's determining what position it's in when in D. Are you just having it count gears by ratio?

 

I did consider an external thing, but that probably would have taken around as long as tapping everything.
My goal here outside of eventual trans control was just to get in-gear or not, which could have been accomplished mainly by tapping the Park sensor because there's rarely a reason to go into Neutral... but it'll be handy to have the whole array for trans control later.

 

There's a B-W wire off the position switch under the truck for D. R,2, and L are tapped off the ECU. Neutral is the only one that doesn't have an independent tap, so I treat them all as analog voltages with Neutral being 0

oh, and P is under the truck too as V-Y...but stupid Toyota decided to put two of those colored wires in the harness I was tapping, so I decided to use the one in the cab

 

Ah okay, I got that part. But you answered the other question too I guess above, so it's just for determining you're in some form of moving gear for idle and whatnot offsets currently. You aren't interested in using the actual gear the trans is currently putting power through for boost control or spool or something.

 

Right, not yet. Actual gear will come when I intercept the solenoids... which tbh should be really easy in comparison

 

I'm not sure if this helps at all, but you just need 2 inputs and a few conditionals to determine gear 1-4 gear state. I skipped it for now because I don't want to make another mess of wires if I'm going to be switching them to outputs in a bit.

 

Ive determined all of trans control can be done with only using 7 additional Haltech pins. 6 if you don't care about how confused it'll be in low range

 

7?
3 solenoids
1 ETC switch
1 O/D switch and..?

 

Brake switch, input VR sensor, I actually didn't even think about the ECT switch cuz the function is dumb. But I suppose you could always implement a shift strategy switch. And something to tell when you're in four low. I would just use a rotary trim module and assign one of its functions to be the shift strategy switch to not waste inputs that way you can still use it for something else but really with the health tech you could just program a shift strategy you like rather than choosing between the two stock style ones that kind of suck

 

Oh ok, you're counting ones already in too

 

Do you have a brake switch wired in. I haven't seen any that come with it wired in already.

 

Yep, and I always wondered why because it does nothing

 

With all this talk, I think I'm gonna start setting up a template

 

I started jamming together a little conversion box. Got to have relays for the high side drive solenoids unfortunately they fall just outside of the range of what the haltech can output safely. I'm actually just now finishing putting together my loaner vehicle so that the automatic truck can come back here for full trans control. I'm hoping there's enough I/o left over to do drive by wire. Blips for downshifts would be sweet