D21 Diesel tacho

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tarrantw

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Hi guys,
Have searched but to no avail, have done a turbo engine swap on my terrano and have found out that the tacho signals from na to turbo are completely different and have purchased an aftermarket diesel tach.
I have tried all the outputs from the alternator and the signal wires from the turbo motor but I can still not get the new tacho to work. Its an autogauge diesel tach with power and one green wire for signal. Just wondering if anyone could point me in the right direction?
Regards Taz.
 
I'm surprised that your tachometer was not plug and play when you went from a TD27 to a TD27T, what year vehicle was the turbo engine from? They should both use an encoder in the timing cover which plugs into the alternator harness, but does not have anything specifically to do with the alternator. The wiring colour/s for the tachometer escape me at the moment, tomorrow when I'm home I'll post again with the colour.
 
Hi Dion, my terrano is an 86' and I was told the turbo motor is from a 1990 model, I read somewhere that the signal from the non turbo motor comes from the timing cover near the alternator and the one on the turbo one is under the injector pump. When I ran the wires from under the injector pump into the loom near alternator the tacho went to 6grand lol and stayed there. Just wondering if there is somewhere to tap the aftermarket tacho off.
 
Standard engine rev sensor wire colours are black with a white trace, and white. I've never heard of the engine rev sensor being in a different position on the '90 Terrano motor.
 
Hi guys thanks for your help, ended up getting the aftermarket tacho going. It wanted to be connected to the W terminal of the alternator but not having this terminal on my alternator this meant I had to open the alternator up and solder a wire from one of the 3 windings and run this to the tacho and first shot it fired up.
Bit more confusing than I first thought but all done now.
Regards, Taz.
 
Just in case anyone else has this problem (and it has been discussed before here) the usual place for the tacho sender on a TD27 is on the front of the timing cover on the LHS near the alternator. The sender on the turbo motor is under the injector pump on the front cover. If you connect the wire on the turbo motor up to the non-turbo loom after you have done an engine swap the tacho will go off scale as has been said above. Even if you adjust the pot inside the tacho you can't get it much under 4k at idle. This is because the number of pulses off the pump gear is 5 times more than off the idler gear. If you want to use the original tacho the options are to buy an after market pulse converter from an instrument supply place (I was quoted $400) or to replace the turbo timing cover with the cover from a non turbo motor and use the techo sensor in its original location. I did this. I also tried to get a tacho from a turbo (Terrano) that fitted my instrument panel but after several months trying gave up.
 
Hi guys thanks for your help, ended up getting the aftermarket tacho going. It wanted to be connected to the W terminal of the alternator but not having this terminal on my alternator this meant I had to open the alternator up and solder a wire from one of the 3 windings and run this to the tacho and first shot it fired up.
Bit more confusing than I first thought but all done now.
Regards, Taz.

Hi

Just a couple of questions: Can you use any one of the windings inside the alternator?
And how do you calibrate the tacho to the correct rpm after connecting? Do you need to go to a diesel mechanic to do this?

Alan
 
solder a wire from one of the 3 windings and run this to the tacho and first shot it fired up.


Hey, Tarrantw - I have a "W" terminal on my alt. I have a D21 which had a TD27T out of a Terrano installed. It doesn't have the timing cover tach sensor and I don't have anywhere else to plug it.

How do I hook up my single-wire-from-the-alternator to the 3-wires-on-the-tacho??

If I do connect it, do you think it'll work?

Cheers,

Chris.
 
d21 diesel TACHO not working.

I bought a 1991 d21 (2.7 diesel, 5 spd 4x4) double cab a month or so ago.

The TACHO needle rests on zero when ign OFF. When the key is turned ON the tacho jumps up to 600rpm, and stays there, no matter what revs the engine does.

I got a d21 w'shop manual but the diagrams are for a model with the Speedo in the centre, Temp and fuel on the left and a small tacho on the right. (Mine has large Speedo on the left, temp and fuel in the centre and a large TACHO on the right.

Consequentially the diagrams of the BACK of the dash panel dont agree with my model.

Can anyone email me a copy of the correct layout AND a copy of the various voltage readings to be taken at certain points on plugs &c on the back of the dash, AND what voltages I should be getting at various points from the SENDER to the actual TACHOMETER (at different revs)

Thanks a squillion, men....hope someone can help!!

Dick Randolph, Cooktown Qld ([email protected])
 
Hi
I'm having a similar problem installing a tacho flogged from a wreck. The sensor is in the TD27T location. I have the plug in the back of the dash but i cannot find where its going to. There is no wiring for it at all in the engine bay. Does the sensor require 12v or is it earthed? On the gauge itself there is +12v, a black earth and the yellow which i presumed goes to the sensor. There is also a black/white on the plug but not on the gauge. What am i missing?

Andy
 
Last edited:
i sorted this out with my d21 td27t. i pulled the QD32 cam angle sensor from my dead old motor (located on the front of engine to the right of the water pump) i noticed a "Blank" the same size and location on the td27t engine. i drilled out the hole with a holesaw carefully and drilled and tapped the threads and used a 3mm gasket. plugged the cam angle sensor back into the loom and all works fine.
 

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