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Author Topic: RB25DET Series 2 RPM wire  (Read 3791 times)

b00stinz

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RB25DET Series 2 RPM wire
« on: February 24, 2014, 05:43:24 PM »
Hey guys my brother's 25DET Laurel doesn't have a working RPM signal, the dash gauge won't work and the new gauge I tried to wire in does not work, the yellow wire to the ECU doesn't change in voltage at all.

The car used to be a Diesel and was converted to 25DET. Does anyone know how I can get an RPM Signal?

Thanks!

Clinton

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RB25DET Series 2 RPM wire
« Reply #1 on: February 24, 2014, 09:37:51 PM »
RPM signal is generally pin7 from the ecu, but sometimes the output is broken, so you can just carefully tee into one of the CAS signals, Can't remember if its the 0 or the 120 that works, but just use a multimeter with rpm function to test before you go cutting/joining etc. Actually use a multimeter with rpm to test the factory output first.

b00stinz

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RB25DET Series 2 RPM wire
« Reply #2 on: February 24, 2014, 11:11:17 PM »
Yeah tested the factory output of pin 7 (yellow wire) and it is just reading a constant voltage of 1 point something, nothing changes.

Clinton

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RB25DET Series 2 RPM wire
« Reply #3 on: February 26, 2014, 09:33:35 PM »
Use rpm meter not just volts.

b00stinz

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RB25DET Series 2 RPM wire
« Reply #4 on: February 27, 2014, 08:58:34 AM »
RPM Meter as in a tacho?

What I found was that the voltage I get off that wire off ECU is the same voltage that comes off the plug that goes into the dash cluster and the dash cluster does not work.

But if the wire is sending a signal shouldn't the tachometer I wired to it work?

fast4motion

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RB25DET Series 2 RPM wire
« Reply #5 on: February 27, 2014, 12:50:57 PM »
Tacho signal output from an RB ecu is different to the signal from many other cars, so often a non-standard or aftermarket tacho won't work. So maybe the tachos you've used are just incompatible (sometimes you can connect a resistor in parallel to a 12v source to make them work).
But I also know of a few RB ecus where the rpm output is simply dead, so that could also be your problem.

b00stinz

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RB25DET Series 2 RPM wire
« Reply #6 on: March 01, 2014, 10:28:55 AM »
The tacho is an autogauge one and I have wired one in previously and it has worked fine on the RB. The key I think is that the 25DET has been put into this laurel that used to be diesel. So something has gone wrong during the swap?

mŮk

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RB25DET Series 2 RPM wire
« Reply #7 on: March 01, 2014, 11:36:13 AM »
The voltage doesn't change, it's a square wave signal. You have to check it with and oscilloscope or rpm/hz on a multimeter. And it's a low level signal so most aftermarket rev counters don't work straight off. You otherwise have to put a resistor in or go off the cas wire at the ecu
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