Signal divider for second speed sensor ECU input

[2JZR31]

Easy fix for dividing pulse by number is to use a 4017 chip. cost about a dollar or something from jaycar or dse. Basically a 1-10 counter chip. Give it a pulse and output 1 goes high another and output 2 goes high...all the way up to 10. By joining one of the outputs to the reset pin you can make it count/divide by 1,2,3,4... or what ever you want. then cascade two circuits to divide by any number up to 100.
I have used one in a cressida/1uz conversion were the speedo read something like 7 times too high and I couldn't get another signal to work.
search for 4017 and i'm sure there will be heaps of circuits or if you get stuck i'll dig one up for you.
very easy circuit to build and very cheap

Sweet. Can this be made to go the other way so more pulses come out than go in?

[SL666]

i think we used that chip.. or something very simular...

[wilbo666]

Sweet. Can this be made to go the other way so more pulses come out than go in?

No.

Cheers
Wilbo

[2JZR31]

I got the speedo working with 2 jaycar speedo correctors.

Thing is I think I might still have a speed cut. Is this even possible without the other speed sensor connected? It never used to do it. Could the ECU have outsmarted the missing signal and is using the other speed sensor to initiate the cut?

[CrUZida]

As far as I can tell SPD is what it uses for speed cut.
I'm not sure if SP2 is used, as the ecu doesn't know what ratio diff you have.

If the speedo is accurate and giving 4 pulse/rev to the ecu, then speed cut should be at 180kph

To fool the speed cut you will need to have a box that plateau's the speedo 4 pulse/rev output at about 170kph.

[2JZR31]

Hmm, this happens at about 5500RPM in 3rd. That would be fairly close to 180 wouldn't it? Strange since I don't have any signal comming back from the speedo head. Is there any other cut this might be?

[CrUZida]

With roughly a 3.6:1 diff 5500rpm in 3rd would be 180kph yes.
It is possible that the SP2 ouptut from the speedo is causing the speed cut, but that pulse would differ depending on what diff ratio you have.

[2JZR31]

Which one is SP2? Is that the one that goes straight to the ECU?

[CrUZida]

Yeah, the sensor on the back of the box that picks up the rotation of the output shaft. (not the gear driven one)

[Norbie]

According to Mos, the speed sensor on the transmission is the only one normally used by the ECU. The one on the speedo is apparently a "backup" and under normal circumstances it's ignored. What this means for you is you'll get speed cut no matter which speed sensor you have hooked up.

[SL666]

Norbs: i dissagree with that at least with the soarer setup i use.. we could only get the trans half-working with only one sensor hooked up.

[CrUZida]

I've had the trans working perfectly without SP2 input.
Then SPD died on me and I lost Drive and OverDrive.

I can't see the ECU using SP2 as the speedcut sensor, unless it has a predetermined pulse that it cuts out at in the event that SPD stops working (as per 2JZR31's findings).

[sideshow]

r31 skylines have a digital signal and has 10 pulses every revolution of sensor

1js have 4 pulses every rev up to speedo

the r31 sensor will screw onto the 1j
as toyota and nissan use same thread

if u need signal dividers i sel lthem

they arent cheap but work very well

they have very fine adjustment much better than some of the vdo ones

wasy way to do this is either

run r310 speedo srive to get speedo accurate
then run a divider of the signal wire to the ecu so the ecu gets 4 pulses every 10 so thats a 4/10 division or 2/5

or you can run a toyota 4 pulse speedo sensor straight to the spd signal on the 1j ecu

then splice of it and run a divider/multiplier unit up to the speedo to get it accurate
this woul dbe better option so as u can adjust yr speedo if u change diffs or tyre sizes