So these Nissan motors, don't have a single tacho wire under the hood that you use to hook up a tacho, when adjusting ignition timing when servicing like the RB30's? Alright for the dealers, as the dealers probally just use "Nissan Consult" to get the info from the car during tune up. But what about the average joe, that might want to check it themself.

You have to do one of either solutions do what I did, make a simple circuit or what RyRY said use a resister both work well

What are pins 7 and 49 for, haven't got a pinout handy? And the 10k would only be appropriate on the VL Tach only i would imagine?

Pin 49 is 12v from the ECU relay. Pin 7 is tacho out. (RB25) The VL tacho signal comes from the negative side of the coil, so it produces a signal which switches from 12v down to 0v. The tacho signal on a 20/25/26 comes from the ECU (pin 7). I havn't measured it but it musn't switch to 12v. This is why you need a pull-up resistor to 12v. The value of the resistor isn't critical but i wouldn't use anything under 1k or you could overload the tacho. Dunno about other aftermarket ecu's, but the haltech e11 has a "tacho out" pin. You connect this to the vl tacho wire (brown/red), and then configue it in the software. It has the option to use an internal pull-up resistor to 5, 8, or 12v and the ability to set the number of ignition pulses per revolution (3 for a 6cyl). Simple.

Cheers MonstaS4, some good info. Some original photos have not been recovered yet.

Quote: Originally Posted by Dimebag Hey guys, just a quick question, i got a tacho dash for my VL, RB30. Now, i've got the stock cluster in there atm, (speedo, clock) and was wondering what needs to be done so that i can get atleast the tacho working. I was told that its just a matter of plugging the thing in and off you go, but im unsure if this was correct advice?? Any help would be greatly appreciated. the tacho dash plugs in to the standard loom, all the wiring is factory no changes needed, thats all u need to do for it to work. I've been reading this thread and there's alot of mixed answer, to me making the circuit for ur tacho to work with the rb25det, sounds the safe way to go as it use's diode's so there is no change of back feed to the ecu, the resister way, is there any change of back feed to the ecu and damaging ur ecu? any info will be a great help cheers

i made the box and works perfectley reccomend the box way with the diods.

Quote: I've been reading this thread and there's alot of mixed answer, to me making the circuit for ur tacho to work with the rb25det, sounds the safe way to go as it use's diode's so there is no change of back feed to the ecu, the resister way, is there any change of back feed to the ecu and damaging ur ecu Back feed? The RB20/25 ECU creates its tacho signal by switching pin 7 between ground and open. The tacho itself internally connects +5V to pin 7. This results in a 0-5V square wave. When you remove the factory tacho then you remove the 5V voltage source. This means the sqare wave becomes 0V-0V, ie nothing. A pull up resistor simply reinstates the voltage source by connecting pin 7 to a 12V power source. This can come from anywhere in the car but obviously it has to come from somewhere thats active when the ignition is on. As a result you get a 0-12V square wave which is suitable for driving some tachos. A high resistance pull up resistor will prevent excessive current from burning pin 7 out. If your tacho doesen't respond to a 0-12V signal then you need to come up with some sort of tacho module that produces a signal that matches your tacho design. The sixworks stuff is by far the easiest option I have seen. The one I use took all of 5 min to connect up the 4 wires. $50 well spent. IMO way better than stuffing around making things yourself.

why bother making/buying a circuit when a peice of wire and resistor(costing no more than 20cents and taking less than 5min to install) is proven to work without problems.... and if you have 50 bucks burning a hole in your pocket just donate it to me for telling you this.

i can tell you all, they both work, the easy way is to just use a 10k resister from a 12v in on the ecu to pin 7. by the way i am running a rb20det my 2c

http://www.calaisturbo.com.au/showth...B25+tachometer (http://www.calaisturbo.com.au/showthread.php?t=81275&highlight=RB25+tachometer) this link describes the problems i had with my tacho when the 25/30 went in. i bought the required components and assembled the rev counter circuit for less than 5 bucks and it fixed my problems.

it must be to do with the amount of power to drive the tacho, as i am using the factory dash and it works fine with the 10k resistor, all the way up to 7,000 rpm.

Quote: Originally Posted by joe25482 why bother making/buying a circuit when a peice of wire and resistor(costing no more than 20cents and taking less than 5min to install) is proven to work without problems.... and if you have 50 bucks burning a hole in your pocket just donate it to me for telling you this. A. Because the pull up resistor method doesn't work every time.

i recently tried both these methods pull up resistor didnt work so i made the circuit and still no luck any ideas on where i might have gone wrong, any help would be great

Just wondering if this rev counter works on 94 vr statesman as i recently installed a tacho and it does not read the revs. Thanks

can anyone please help no i have put the rb25 motor in my vl and now im starting on the ecu and in the old rb30 there are two plugs that go from the ecu and up under the dash behind the glove box and one plug is blue and the other is black and can anyone help me out by telling me where each wire from the plugs go into the new rb25 ecu? or even a diagram or something anything i have searched everywhere but nothing please help anyone

10k resistor method works great, Its so easy, Ive missed my tacho not working. not any more Some original photos have not been recovered yet.

I'm a little confused as to how to attach the resistor..... Am I right in thinking you get a piece of wire, solder one end to one side of the resistor and the other end to the 12v in on the ecu, then solder another piece of wire to the other side of the resistor and then that wire to the tacho out (pin 7) then attach that to the tacho in wire on the instrument cluster? OR can you just hard wire the resistor to the 12v and tacho out wires? Also am I correct in thinking the 10k resistor used is: Brown , Black, Orange, Gold (10Kohms. +/-5%)?

at the ecu end, find those two wires, strip some insulation off, then solder each wire leg of the resistor to each wire, then insulate. could not be easier. google search will have resistor colour charts, usually its written on the packets if you go to jaycar etc, so its easier to identify.

Great, so hard wiring it is the go Does the tolerance of the resistor matter? The resistor I have is 10Kohms which is fine but it has a gold stripe as the final stripe which is the tolerance. Gold = +/- 5%. No-one at Jaycar seemed to think it mattered but I don't want to fry anything Some original photos have not been recovered yet.