Need help installing tachometer

[wideawake]

Hi all,

I recently got a tachometer that I want to install to my car. I have made all the necessary power wiring connections. And I have confirmed it using a multimeter.

This is a Defi D-gauge tachometer. If I switch on the lights, the meter would light up. But if I put the ignition to ON, or even start the car, the meter does not move at all.

I took the tachometer signal input from pin 7 on the ECU. Is this the correct way? The manual said to put the tachometer signal to the negative terminal of the distributor. Which I'm not sure where it is.

Another question, is the Accessory(ACC) and Ignition ON wire power up at the same time when the key is turned?

Thanks.

 

[coldair]

wideawake,
- Red wire goes to +12 volts.
(taps into permanent +12volts battery power for Defi gauge)
- Orange wire goes to IGN ON.
(+12volts power provided to Defi gauge when ignition is turned ON.
- White wire for illumination
(taps power from "lights On" switch for lighting up the Defi gauge)
- Black wire for ground.
(this is the power supply ground terminal, connect this wire to chassis ground)
- Signal wire
(This wire is the signal input for the Defi tachometer, it picks
up the rpm signal from the negative side of the high tension coil on a
distributor system, in your case this wire should be connected to the RPM
output of your RB20DET ECU.
- Number of cylinders.
(You have to set the DIP switches to reflect that you have a 6-cylinder engine).

Good luck..

 

[wideawake]

Wahlaueh... u have this type of meter also issit?

Then could be because my RPM signal is not connected properly lah.... Have to search for the ignition coil lah like this...

 

[wideawake]

It's been sometime since I started this project and never got to finish it. Today, I finally got some time to do it. I got the Defi tachometer functioning (started the opening sequence).

But I'm not getting any signal from the pin-7 from the ECU. Maybe some wires were not connected during the conversion, and pin-7 does not show any signal. If this possible?

I read I can also get the signal from the negative terminal of the ignition packs. Anyone knows where this is located in this engine?

Thanks.

 

[zephuros]

Hey dude, when you said you got it functioning that only means you got it powered. You still don't have the tachometer signal going in. Yes you are right it is pin 7. Are you getting any ECCS warning when you start or go to IGN? If you do check the CAS circuit. I think the CAS uses pins 41,42, 49 and 50 for 120degree signal, 1 degree signal, supply and GND.

Err... does the tacho on the dash of your car work? if it does then definitely got output from PIN # 7.

 

[a31gtst]

Its very peculier tht there is no signal from no 7...

Make sure when ur looking at the wiring loom u dont accidently look at it sonsang! kekeke i did tht once but luckily there were existing wires tapped as reference.

The ignition coil packs sit under the Cam cover, each spark plug has an ignition coil pack and the harness goes to the ignition amplifier...this sits right at the back and on top of the cam cover...am not sure but u could try meggala or some other sites for a diagram on the ignition amplifier and pull a fresh wire frm there thru to the meter.

Cheers

 

[zephuros]

errr.. for tachometer singal comes from Crank Angle Sensor, not coil...

 

[wideawake]

Erm...

The RPM meter on the dash doesn't work. Because it is from the old car (carb). My halfcut didn't come with a meter on it.

I notice there is a socket not connected at the ECU wiring loom. There is a yellow/red wire that looks like the wire from pin-7.

My ECCS warning also dun have... dunno what it is for.

 

[a31gtst]

that might be it...not sure on hand of the color code for the speed signal wire.
give it a try and you might have just solved ur headache! :P

if ur gonna strip any wire...make sure the ign is off...just to be safe


cheers

 

[wideawake]

I got this from skylinesaustralia.com

Makes sense?

Taken from http://www.skylinesaustralia.com/forums/sh...highlight=tacho

My understanding of how it all works.....this is not neccesarily completely correct

Tacho's work by picking up voltage pulses. Some work off high voltages (eg 200V tachos designed to work from ign coils), others work off 12V and some work off both. OEM tacho's work off a variety of voltages.

The RB20 ecu generates the tacho pulses by earthing pin #7 to ground. The std tacho works off a 5V square wave and there is some special electricketry in the tacho that provides 5V to pin 7 so this wave can be generated.

Connecting pin 7 straight to the pulse input of a non standard tacho will in many cases do nothing because the tacho doesn't provide any voltage to the ecu pin and therfore it is effectively switching between 0V and 0V.

A "pull up" resistor can be used to provide potential to pin 7. If you connect pin 7 to the tacho pulse input and then get a 10k ohm resistor and connect it between a 12V supply and pin 7, then the tacho will see 12V-0V input as pin 7 switches between open and ground. The 10k resistor will prevent too much current from flowing through the ecu and frying the tacho circuit. Cost ~$1.

 

[wideawake]

Yes... This really makes sense... Finally managed to install my tacho.
Got some resistors and fuses and wired it all up.

Very satisfied now.