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
http://i927.photobucket.com/albums/ad117/jaido92/WP_20160217_16_28_02_Pro_zpsknq8zmoq.jpg (http://s927.photobucket.com/user/jaido92/media/WP_20160217_16_28_02_Pro_zpsknq8zmoq.jpg.html)

ive then traced that plug and it ends here
http://i927.photobucket.com/albums/ad117/jaido92/WP_20160217_16_28_37_Pro_zpss69uix8o.jpg (http://s927.photobucket.com/user/jaido92/media/WP_20160217_16_28_37_Pro_zpss69uix8o.jpg.html)

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

http://i927.photobucket.com/albums/ad117/jaido92/WP_20160217_16_29_24_Pro_zps2tu8suev.jpg (http://s927.photobucket.com/user/jaido92/media/WP_20160217_16_29_24_Pro_zps2tu8suev.jpg.html)
http://i927.photobucket.com/albums/ad117/jaido92/WP_20160217_16_29_54_Pro_zpslf1we1dw.jpg (http://s927.photobucket.com/user/jaido92/media/WP_20160217_16_29_54_Pro_zpslf1we1dw.jpg.html)

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.

64946

64945

[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.

http://i927.photobucket.com/albums/ad117/jaido92/WP_20160218_09_32_29_Pro_zpsatamioz0.jpg (http://s927.photobucket.com/user/jaido92/media/WP_20160218_09_32_29_Pro_zpsatamioz0.jpg.html)

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

[jff45]

Did you rev it over 1000 rpm?

Do you have a voltmeter to measure AC volts across the 2 sender wires? Should be around 1v AC at idle

[Yendor]

Without the ECU you will need to connect one wire of the sensor to the yellow wire with a black trace (pin 5 ECU connector or pin 44 instrument cluster) and the other wire will need to connect to pin 6 in the instrument cluster (Y-Bl yellow with a blue trace in your diagram).

[jff45]

I'd be interested to know if there was a good result with this.
It could help others in future.

[jaido]

Tacho is all working, got nothing at idle though, my thinking is i could possibly have a faulty instrument cluster, i have no idea if the tacho worked before i pulled the 2.8 out, i never drove it. my blue wire went to the Y-bk and green went to earth.

[jff45]

There's nothing wrong with your tacho. What you're seeing is what the TB45 conversion guys have seen when they connect the TD42 sensor directly to the tacho - nothing below 1000 rpm.

The solution I found was to wire a Dakota Digital box between the sensor wire and the yellow/black that goes to the tacho.
It must just amplify the signal enough to make it work.
My tacho works perfectly now. Checked it with a digital tacho.

[jaido]

ahk, any particular one? http://www.dakotadigital.com/

ill get one of them soon as i have a job again.

but at least ive got something now, ive been curious to know what my rpms are with my 35's and 4.6's

[jff45]

This one..
...

[jaido]

sweet, thanks john.

[Kimbo63]

Hi jaido did you try what Yendor suggested? Would be good to know outcome
Cheers Kimbo

[jaido]

that's what I tried first,
Probably worked aswell but I never bothered to rev the engine I just had it idling and assumed I did it wrong when the tacho wasn't working.

I am having one problem now though and cant figure out where, Fuse 24 (7.5A) keeps blowing and only started since wiring up the tacho.
ive looked everywhere to see if Ive skinned a wire anywhere and may be shorting out, but I got no idea

[jff45]

Probably would have worked too if that yellow/blue wire was earthed. The sensor is an inductive pickup so one of the wires should go to earth.
I'm guessing the TD42 tacho/cluster has slightly different electronics to amplify the signal.

My TB45 tacho and wiring is the same as I suggested to you except I have the Dakota box to amplify the signal.

In all the conversion threads I've read, I haven't found one that was able to directly connect the TD42 sensor to the tacho.
It has worked for those who swapped their cluster for the TD42 unit.

[jaido]

yeah, the few threads I read on the other patrol forum, the guys wired the tacho into the loom in the engine bay and worked, but the sparky that did my conversion chopped it out.

[Eli]

hi all
Did jaido end up finding a solution? I'm having the same problem with my tacho. Any help would be greatly appreciated

[DanielSedgman]

Any updates on a tacho fix when you swap the ZD30 engine for a td42 engine?

[jff45]

Any updates on a tacho fix when you swap the ZD30 engine for a td42 engine?


The usual fix is to simply use a Dakota Digital tacho signal converter between the TD42 signal and the ZD30 tacho wire cut from the ECU. This assumes that the TD42 doesn't have the TD42Ti cam gear.