Tacho for a rd28 to TD42 conversion

[jaido]

so ive read countless threads on this and havnt really gotten the answer im looking for, Im wiring up my tacho coz its finally giving me the chits

so ive got the sender that is on top of the timing chain, ive following the wires coming off that and it goes to this plug


ive then traced that plug and it ends here


so now where do i wire it up from there, my workshop manual only has one small schematic on the tacho and it doesn't tell much




Ive read about how the TD42 has two wires from the tacho while the RD28 has three. The RD28 has two earths and one power for the tacho, and you just hook up the two earths to the single earth on the TD42 tacho and it will work.

where do i find these 3 wires, or has my auto sparky chopped them out when i got him to do the wiring on my conversion last year.

[jff45]

I had to use a Dakota Digital tachometer converter to get my TB45 tachometer to work properly. I think I recall a thread elsewhere where they had to do that too with a 2.8.

That plug you're showing is a Deutsch plug, not the standard Nissan plug, so someone has already tried to connect something there.

[Yendor]

The tacho signal comes from the 2.8 ECU. Does your vehicle still have the 2.8 ECU fitted?

The ECU use to receive the RPM signal from the camshaft position sensor mounted in the injector pump.

In the original harness that went to the injector pump there should be a black and a white wire. These two wire connect to the two wires in your photo.

To confirm you have the correct wires. Disconnect the ECU and with an ohmmeter confirm :

The white wire goes to pins 41 and 45.

The black wire goes to pins 28 and 33.

2.8TD ECU.jpg

2.8 ECU2.jpg

[jaido]

I'm pritty sure the ecu has been taken out, I've never seen one in there when I've been tinkering around. Where does Nissan usually hide them?

[mudski]

I'm pritty sure the ecu has been taken out, I've never seen one in there when I've been tinkering around. Where does Nissan usually hide them?

Its should be pretty much beside your left foot, ontop of the transmission tunnel, and above the heater floor outlet, or there abouts. Square flat box about 6 inches square and about an inch or so thick.

[jff45]

If you no longer have the ECU but can locate the plug that went into the ECU, you will find a yellow/black stripe wire on pin 5.
This wire should be connected to your tacho.
You can try to connect 1 of your tacho sender wires to this yellow/black wire and the other to earth.

[jaido]

Its should be pretty much beside your left foot, ontop of the transmission tunnel, and above the heater floor outlet, or there abouts. Square flat box about 6 inches square and about an inch or so thick.

is that the wiring for the ecu? looks like thats all gone.

[jff45]

Isn't that a yellow/black stripe wire I see roughly where pin 5 would be?
If it is, it should be connected to the tacho.

[jaido]

Sure was, so I cut it off connected it to the green wire and the blue to earth, did nothing.
Swapped them around and still nothing.

[jaido]

Alrighty I got something,
Green wire going to the yellow-bk
And blue to earth, BUT at idle I have nothing on the tacho and when I start accelerating the tacho starts going up