1JZ-GE VVti conversion, speedo connection? *solved*

[George]

Hi All,

I'm swapping an 1jz and just have faced the problem that at first glance there's pretty nowhere to take speedo signal from.

The motor is 1jz-ge with VVTi without ETCS. No electronic devices except ECU are available. I also don't know which ones were originally connected (ABS, traction control, etc...). Neither I know what kind of cluster was installed in the original car.

Generally I have 2 speed sensors, SP2 and NCO. The motor came from Japan with A/T with these pickups on it. Analog cluster schematic for 1JZ shows another speed sensor but I cannot locate it anywhere.

Digital cluster schematic shows that on some models speedometer signal is taken from ECU, I haven't checked yet if such wiring is present.

In the worst case I could hand-wire some interface board to accept SP2 signal and convert it to my speedo signal format, possibly correcting its pulses per rev, but for first I'd like to find out if there's any simpler solution.

So, any minds?

[madmont]

I also used a 1JZ-GE VVTI . Mine came from a 2001 Crown . Has ETCS with traction control and speed control in the engine ecu. Had 1 speed sensor on the auto . I went manual so I did not need speedo sensor. My wiring diagram shows no dedicated wire from ecu to speedo so I suspect it goes through the CAN bus. Wiring some tricky electronics from your existing speed sensor to your speedo sounds like the way to go

[George]

Sad but true, thanks ) Either way I was planning to make a speed limit defenser for it in some future, so until then I'd have to count milestones or something )

[George]

Finally done! I have traced ecu's input circuit for SP2+,- sensor , engineered some very simple board (10x10mm, containing only 7 parts) and embedded it into the ECU box, so as not to introduce any interference into the signal fed into processor.

It shows approx. 624Hz at 100km/h , I then took a basic analog speedo and adjusted it appropriately. No trip display yet, tbd, wip etc =)

[madmont]

Well done George. Would you consider posting the circuit so that others may benefit?

[George]

np, I just needed some time to celebrate the mod ) and redraw it from my notebook (I rely on paper much)

Now, for the schematic check the link
http://sites.google.com/site/yurybar...spd/speedo.gif

It shows ECU input, speed sensor model, and my additional circuitry. Bipolar transistor would not be adequate because of its low input resistance, while opamp needs more room and finer board traces.

As for the circuit it's basically an AC-coupled linear amplifier tuned to a gain close to the maximum, so it easily gets clipped by the signal. Which is good for faster transitions. It will pick up a sine signal as small as 500mV RMS. Since FETs are fabricated with noticeably different performance, I think it's 10% probable that you would need to adjust the bias point replacing R1 with 200kOhm trim pot or something like that. In this case you shift to N, jack one rear wheel, supply the circuit with power, spin the wheel, and adjust the trim pot until there're some pulses on the output. Then you'll probably want to fine adjust and solder some resistor instead of the pot.

The circuit is placed inside ECU for several reasons. Forst, I didn't want to cut the loom. Next, in this case you don't need a separate box and wires inside your car. Finally, ECU box is noise shielded. There're free ECU pins, for example X12 which is used as speedo sensor input in 4WD models, according to Toyota schematic. It's not connected inside ECU, so I decided to use it. Then, since I don't have ABS, TRC, TEMS etc, there were enough unconnected wires with terminals crimped on them inside engine loom connectors, so I removed them all and put one to X12 location.

I'm now working on a digital speedo with stepper motor and LCD display (I still need a trip display). The next thing would be speed limiter defencer, though I haven't actually felt the limit yet, only tried 160kmh so far. Just for the reference, the pictures of my swap are at http://album.foto.ru/photos/54459/ , and this is the native engine equipped with my home-made EFI system http://sites.google.com/site/yurybar...02i/ovrall.jpg

[wilbo666]

Good work

You didn't try and pickup off IC??, suspect a Square wave would come out of that

Cheers
Wilbo

[George]

It's a harder work for me (I need to check signals inside ECU and someone need to spin a wheel, that implies I need an oscilloscope, which means I need an AC outlet near my car - that's not always possible), besides I believe that way it's more probable to damage the inside of the ECU (by suddenly shorting the output taken directly from the IC).

My circuit makes square wave, too. The speedometers we have here all assume there's a Hall sensor in the gearbox, so 12v amplitude is a must. I doubt about such a level inside ECU - anyway some additional electonics is required.

[George]

[upd] there are many projects on the web that are related to building DIY speedo and trip indicator using some tiny processor and a simple LED or LCD display. Obviously they benefit in that you can manually tweak pulses per km to any desired value. I could post some of the projects here if it is considered a useful info. I'm quite busy now passing the engineering for my car and swapping my job =) so no analog-looking speedo is expected in near future.

[George]

[upd]
eventually built very simple thing to connect JZX90/100 (and more to come) cluster speedo utilizing auto's sensor. Different versions available. With one of them and Volvo diff (3.73) error is 1.7%. Anyone interested?