diypnp no tacho
 

i wonder if someone could point me in the right direction, i bought a used diypnp which came from the same year car a uk spec mk1 1997 1.6, it also came with Toyota cops harness and ignitors.
fitted it all yesterday and everything went well got it all running on a na base map, the only thing i can't get to work is my cars tacho, the one in tunerstudio works fine, (it's turned on in tacho output in tuner studio)
i can't find a ecu pin-out anywhere for my car to check it's wired correctly ,my car has a two plug ecu and the only pin-outs i can find for a 1997 car have three plugs.
i did take a look inside the megasquirt not that i really know what i'm looking for, there is a wire that runs from the tach on the board to pin-out 4i on the megasquirt and this corresponds with a light green and red wire on my cars ecu but as i can't find i wiring diagram i have no idea if this is correct.
thanks.

i'm thinking it's not wired correctly anyone know what colour the tach wire should be on the cars harness ,i can't find a wiring diagram anywhere for a 1997.

well the tach wire is wired to 4i on the megasquirt which goes to a empty pin on the cars harness, any idea how i can find the tach wire on my cars harness ,everything i've read suggests it should be a black and white wire but there is no black and white wire in my cars harness.

Tach is 4L, not 4I

http://Attachment 176894
http://Attachment 176895

its defiantly on 4i on the megasquirt board , if you look at the cars harness 4i corresponds with the missing ecu pin between the blue and yellow wire and the red and green wire on the right hand multi plug.
4l on the megasquirt board would correspond with the green and white wire on the bottom row of pins on the right multi plug is that makes sense.
it has had the pinouts move as it was originally from a 94 car and the guy i bought it from had it altered to suit a 97 car.

I misread, i thought you had a 97. Looks like you have an OBD-I 94?

no you didn't misread the car is a 1997 uk spec mk1 which is weird because all the info i can find says later cars had a 3 plug ecu but mine has a 2 plug, i've seen plenty of used ecu's for sale for uk 1997 and they also have 2 plug ecu's

Those are OBD-1 connectors.


how many wires are on your (2) coil connectors?

the multi plug on the end of the coils has 3 wires.

i've checked signal wire from the tacho in the car and it is a black and white wire, the same colour on the coils, all the wiring diagrams i've read suggest this black and white wire runs from the ecu, but my ecu has no black and white wire.
tacho works fine with cars original ecu

You have one of these ignitors?

https://www.miataturbo.net/attachmen...ine=1327066127

If you do, I would trace the 5th pin black/white wire back to the ECU harness to figure out which wire it is for sure. Chances are it's the same color as it is on the ignitor on your car, but just to be safe...

Then jump the tachout on the MS over to the corrosponding pin on the harness.

You're not done yet, you need to cross two wires at the ignitor. The yellow/blue wire on the tach needs to be crossed over to the black/white wire. This will send the megasquirt generated pulses straight to the tach. Check your colors, if it's the same ignitor part number just go by pin number.

Make sure you turn on tachout in your tune, too.

Of course with toyota coils you should just be able to splice two of the four cop pins over to the blue/yellow wire in your ignitor patch harness thing. They generate the same pulses a megasquirt does, or at least they should.

This car have an ignitor?

probably still gets tach from the ignitor (why coils plugs only have 3 pins [power ground and trigger]).


try adding a 1K resistor in the diagnostics box from ig- to b+ -- the ECU was providing a 12v pullup to the ignitor, but since you removed the stock ECU it's now unpowered.



edit: deezum posted at same time I was writing. You do have a lot of wires populated on the ECU harness that a normal 9093 1.6L doesnt have, but it matches most of it.

yes i've got an ignitor and it's wired the same as in your pic, wire no5 (black and white) runs to the coil packs and i've traced this wire back to the ecu and if you look at my pic of the cars multi plugs it traces back to the blue and red wire on the lefthand multi plug ,top left wire.
so do you think i need to move that blue and red wire to 4i on the megasquirt wich is tach out on my board.
also don't know if it makes a difference but my cops are not wired from the ignitor ,they are wired from the db15 plug on the megasquirt.

sending tachout to that wire wont help.

just do what i suggested.


edit: wired directly to db15? what? so your DIYPNP is using High Output drivers?

ok will have have to get a 1K resistor i don't have one to hand, i've know idea if it's using high output drivers how would i tell ?
the car had a harness made that runs from the db15 to the cops with a relay that has power feed a switched live and an earth, the cops are only using three of the pins.

http://Attachment 231794

Attachment 231795

In that case you probably need to add the 4th pin to two of the coils and wire it over to the diagnostic box, or I guess you could just jump the megasquirt directly to the gauge cluster and use it's tachout. If the car had a ignitor, you could still use those wires...

Never seen a COP install quite like that before...

So i jumped a wire from the dash gauge to the tach out on the megasquirt and it works, so just need to run a more permanent wire and that it sorted.
i bought the megasquirt used off eBay and the auction didn't even mention cops ,when i asked the guy about it he said the harness was made by a well respected guy here in the UK ,is there a problem with the way it's wired ?

It's just odd (well, different). nothing inherently wrong with it.

great, thanks for all your help guys, i will just run a permanent wire from the car tacho to the megasquirt, i had another problem with the cooling fans not coming on, my fan was wired to 1L and should have been on 1R , moved the wire and it's all working great.