No tach read out...

Discuss the RB20, RB25 and RB26 series engines.
sil820
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My speedometer works, but i have no tach read out.. do i have to change my gauge cluster to get it to work?? or can i stick with my orginal gauge cluster? if i do need a new gauge cluster do i have to get the R32 gauge cluster? i have the RB20det. thanks guys for your help


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xjon
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It should work with the original tach (KA's). Check your wiring with a digital meter from tranny to ecu and ecu to tach wire. I don't know what wire or pin # it is since I have an RB25.

I'm in Mission Viejo. I would like to see your ride and maybe help out if you dont mind. Just mail me [email protected]

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You will need to run a pull up resistor on it and recalibrate from 4->6cyl.. either that or fit a C33 Tacho into the dash.

frosted flakes
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for the tach u have to hook up the yellow/red wire with silver stripes on the white rb plug to the brown gauge 240sx cluster plug on the passenger side.... same with the water temperature sensor....there are pics here about 3/4 the way down...

http://www.nissaninfiniticlub....iring

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You need to remove the RB temp sender nd replace it with the orginal KA,CA sender.

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PROJECTRB240SX
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ACTUALLY, THE KA24E AND RB20DET SENSORS ARE THE SAME. THEY BOTH READ THE SAME TEMPS ON MY GAUGE AND EVEN HAD THE SAME NUMBERS ETCHED INTO THE NUT.

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RB and CA are different.

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rbsileighty
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GTR Shop wrote:You will need to run a pull up resistor on it and recalibrate from 4->6cyl.. either that or fit a C33 Tacho into the dash.


I saw this in another post, that is a 10k ohm pull up resistor correct?

I love the R32 GTR on your webpage... that is my perfect GTR, even down to the color!

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Yes 10k resistor.

-------------------------------------12v+ | 10k

|-------------------------------------dash tacho feed from ecu

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rbsileighty
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Perfect, thank you very much! With this mod, how close was the tach's reading to the actual after its final adjustment (considering you measured it against some other form of reading the signal)?

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Its way out as its a 4 cyl tacho getting given a different input. There is a pot on the back you can get some adjustment with, but IIRC you may need to throw a 3k resistor inline witht hat also to get enough adjusment.Once adjusted, we had it with 50rpm on a acurate digital readout (S-AFC or RSM are good also)The tachop scale isn't quite right from factory.. if you calibrate it at say 5000rpm, then it will prob be a tiny bit over at 8000rpm and a bit under at 2000rpm.Some tachos with pullup and adjusted may be a bit lazy on their response.

The C33 tacho is the better option..bolts in and works straight off.

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rbsileighty
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I knew the 4cyl tach would be off since it was receiving the PPR signal from a 6cyl. I have been looking for what the proper resistance that would convert it to a 6 cyl tach for the past little while. I was actually really going to tear into this issue in April, since I will be having some more time in the afternoons, but it looks like you have solved it already... thanks for the help!

frosted flakes
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PROJECTRB240SX....

you are right, they RB and KA temp sensors are the EXACT same...exactly exactly exactly....they read out the same but for some reason the rb is a little bit slower than the KA sensor...i have an infrared thermometer and i just point the laser to right under the temp sensor and i read out a perfect 162F after driving! yes no overheating on the KA radiator wooo hooo!

frosted flakes
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GTR SHOP....

so you are saying if you put a 10K resistor in between the tach signal wire to the tach it will read correctly?? Isnt this tach signal wire measured in pulses?

sil820
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so all i have to do is put a 10k resistor on the wire? and my tach will start workin?? i think i can do that.. but im not good at wiring at all

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Yip, 10k resistor .. 1 end of it on 12v+ and the other end on the tach wire from ecu-dash.

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rbsileighty
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Quote »you may need to throw a 3k resistor inline witht hat also to get enough adjusment.[/quote]

So this is just an extra if the 10k isn't enough I am assuming. This will actually go inline with the signal wire, or it should be a pull up between the 12+ and the signal (like the 10k)? I am an ME... EE lingo is kind of rough, but I think I understand. Thanks again for the help!

Have you done a lot of S-chassis RB swaps? Any other cool fixes you could share?

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The 10k is 1 end on 12v the other on the signal to the tacho.

On the back of the tacho, is a pot. (variable resistor) you 'may' have to unsolder one fo the legs of the pot and add a 3k resito to that and back onto the board to give it enough range of adjustment.

I should get a heap of C33 tachos next time I'm getting parts and send them over to your guys. ;)

Yes... I've messed with S13s and RBs a bit ;)We get the mighty CA18 in our S13s ;)

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rbsileighty
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GTR Shop wrote:The 10k is 1 end on 12v the other on the signal to the tacho.

On the back of the tacho, is a pot. (variable resistor) you 'may' have to unsolder one fo the legs of the pot and add a 3k resito to that and back onto the board to give it enough range of adjustment.

I should get a heap of C33 tachos next time I'm getting parts and send them over to your guys. ;)

Yes... I'm messed with S13s and RBs a bit ;)We get the mighty CA18 in our S13s ;)


Yeah, I got the first one the first time. Now I understand what you meant with the 3k one... that shouldn't be a big deal.

I'm sure you could create quite a business with us over here, as long as shipping wasn't to crazy. Let me know if you run across a VPC for the RB20DET!

If it makes you feel any better, over here the "mighty CA18" is considered an upgrade to our KA24.

Thanks again for the help!

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VPC??The CAs are great little motors.Doing a big turbo on one at the moment, with fornt mount, RB25 AFM and custom chip tune.. will rev it to 9000rpm.. all std internals etc, and still running the auto ;)Hopefully get it to run in the mid 11s.

frosted flakes
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probably get a 10K variable resitor from 5-15K and put it in the signal and adjust till its correct...i will try this thankyou sir!

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rbsileighty
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A VPC is a unit from HKS (Vein Pressure Converter), which allows you to eliminate the MAF in favor of a MAP setup. It would only be a temp fix until the Microtech came along.

I don't know if anyone has said this yet, but welcome to NICO GTR Shop!

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JonPowell
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The RB20 and KA24 temp sender may be the same, but the RB25 IS different, it doesnt work with the KA gauges either.

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PROJECTRB240SX
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THATS WHY I SAID THE RB20DET SENSOR.... I FOUND THIS OUT WHEN I SWAPPED IN THE KA ONE.

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Wulfgang
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I think they also said KA24E sensor, not KA24DE. I would have to do more testing to verify, but at first look, it seems like the RB20 sensor reads a bit higher than my KA24DE sensor (S14).

Also, I can confirm that the KA24DE (S14) and RB20DET thermo sensors are NOT the same physically. In fact, the RB20 connector doesn't quite fit right on the S14 sensor.

frosted flakes
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I know the KA24DE (92' s13) and my rb20det (91' skyline) is the exact same physically and has the same output...except the skyline temp sensor takes a bit longer to heat up.

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JonPowell
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Ok, good to know that the RB20 is the same...I should have known they would use the same for those motors...same year runs & all...

So back to the tach problem, any luck yet?

PsiloX
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Will that 10k ohm resistor install get my stock tach to work in my 90 240sx (it had a SOHC).

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Wulfgang
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Don't even try to swap an older tach into an S14. I just tried, and the tachs are different enough so that the older one I tried (from the RB20DET) would not even fit in the space in my cluster.

I'm going to try to find a white-faced tach from a Nissan V-6 from the 1995ish era. Anyone know where I might find something like this? Did the Maximas come with white gauge faces?

sil820
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i think im just goin to use my apex rev/speed meter instead of hookin up the normal tach


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