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2000 Lancer CE Negative Tach Signal

Printed From: the12volt.com
Forum Name: Vehicle Wiring Information & File Requests
Forum Discription: Request Car Alarm, Car Stereo, Cruise Control, Remote Starter, Navigation, Mobile Video, and Other Vehicle Specific Wiring Info, Manuals, Tech Tips
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=97121
Printed Date: December 05, 2021 at 8:14 PM


Topic: 2000 Lancer CE Negative Tach Signal

Posted By: ice32
Subject: 2000 Lancer CE Negative Tach Signal
Date Posted: August 06, 2007 at 2:27 AM

Hey,

I'm trying to locate the tachometer signal wire in my lancer 2000 ce to install a RPM tacho i know its a white wire as i have a wiring manual for the car, I'm just unaware of its location in the car and how to identify it.

Any help would be great.

Thanks in advance



Replies:

Posted By: eurobink
Date Posted: September 07, 2007 at 1:15 AM

try BLACK / YELLOW or BLACK/ green at ignition coil

if that fails, find the connector on top of trans.. typically less than four wires and have at it





Posted By: ice32
Date Posted: September 14, 2007 at 3:48 AM
Hey,

I have a tachometer that required positive pulses to calculate the RPM but my cars ECU outputs negative pulses.

Is there anyway i can convert the signal to positive?

Thanks in advance for any info.




Posted By: KPierson
Date Posted: September 14, 2007 at 7:18 AM

You could use a PNP transistor.  Wire the base through a 33K ohm resistor, the emitter to 12vdc, and the collector will be your + output through a 100 ohm resistor.

You could also get fancy and optoisolate it.  On the output of the optoisolator you could pull off a + signal.



-------------
Kevin Pierson




Posted By: ice32
Date Posted: September 14, 2007 at 8:20 AM
hmm, that went over my head, would you be able to simplify it a little please?




Posted By: KPierson
Date Posted: September 14, 2007 at 2:45 PM
Look for a transistor - like a 2n3906 and follow the pinout on the back - it is a three pin device.

-------------
Kevin Pierson




Posted By: ice32
Date Posted: September 19, 2007 at 4:53 AM
So i've wired it up like so
posted_image

Is there anyway i can test its gonna work before plugging it into my car and risking the chance it will fry my ECU?




Posted By: KPierson
Date Posted: September 19, 2007 at 5:40 AM

You may want to check your wiring - the base should have the (-) signal and the emitter should have the 12vdc feed.  You may have it right, but on the 2n3906s I have the base is the middle pin.

You can test it out by metering the collector, after the resistor.  It should read 'OL' (open leg) when the base is NOT held to ground.  When the base is held to ground the collector should read 12vdc.



-------------
Kevin Pierson




Posted By: ice32
Date Posted: September 19, 2007 at 5:49 AM
yep, checked the wiring the base is the middle pin, i'll test that out soon,

thanks




Posted By: ice32
Date Posted: September 19, 2007 at 8:24 AM
Thanks heaps, it worked like a charm!





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