tachometer signal wire
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TECH Apprentice
Joined: Jun 2002
Posts: 319
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From: NH
tachometer signal wire Alright, I went through nearly every page of my Helms manuals looking for the tach signal wire. The only clues I got was that it was in C105. I know where that connector and wire is but before I tap into it, I would like to see the actual circuit diagram. Can not find it anywhere. It is circuit number 121. Could anyone tell me what page in the manual it is on? I like to make sure that it is going to work first in my head before my hands to the work. (Probably because I am an electrical engineer <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> and just a little bit quirky that way)
On The Tree
Joined: Apr 2002
Posts: 112
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From: Ottawa, ON
Re: tachometer signal wire I don't remember seeing a circuit diagram of the tachometer. Just the circuit number and connector which you have. One thing I do know is the Tach has to be set to a four cylinder in order to read correctly. My first tach when I installed it read twice as high as the RPM reading on the scan tool.
After several discussions with the manufacturer of the tachometer they agreed to send me a 4 cyl tach in exchange for the 8 cyl tach. They said it wouldn't work but to let them know. God, did I enjoy calling them back to say it was working correctly.
After several discussions with the manufacturer of the tachometer they agreed to send me a 4 cyl tach in exchange for the 8 cyl tach. They said it wouldn't work but to let them know. God, did I enjoy calling them back to say it was working correctly.
Re: tachometer signal wire the pin your looking for is pin G or the white wire that comes from pin 10 on the red connector of the pcm
<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
Teching In
Joined: Oct 2002
Posts: 49
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From: NE Ohio
Re: tachometer signal wire </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">
My first tach when I installed it read twice as high as the RPM reading on the scan tool.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I'm confused... If the signal from the PCM is equivalent to a 4 cyl, wouldn't the tach read half of what it should because it is getting half of the pulses per rev than you would from an 8 cyl? What am I missing?
I've bought a 4 cyl tach for the car and want to make sure that I'm doing the right thing.
My first tach when I installed it read twice as high as the RPM reading on the scan tool.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I'm confused... If the signal from the PCM is equivalent to a 4 cyl, wouldn't the tach read half of what it should because it is getting half of the pulses per rev than you would from an 8 cyl? What am I missing?
I've bought a 4 cyl tach for the car and want to make sure that I'm doing the right thing.
Re: tachometer signal wire On Autometer gauges there are five wires that you must connect a power, ground, the signal wire. and a brown and green wire that come out of the housing and go back into it I believe. To make it work you need to cut both the green and brown wires in half and tape them of so they don't touch, the tach then sets it's self up as it ready to work with a four cylinder. which you tap into for the # 10 pin of the red connector for the pcm.
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<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
Re: tachometer signal wire </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by pmg:
I've bought a 4 cyl tach for the car and want to make sure that I'm doing the right thing. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You're correct. The LS1 computer works on a 4cyl cycle, so you will simply hook it up directly to your 4cyl tach. It is the same thing in our RX7 swaps as the TT 13B also works on a 4cyl cycle.
I've bought a 4 cyl tach for the car and want to make sure that I'm doing the right thing. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You're correct. The LS1 computer works on a 4cyl cycle, so you will simply hook it up directly to your 4cyl tach. It is the same thing in our RX7 swaps as the TT 13B also works on a 4cyl cycle.
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Thread Starter
TECH Apprentice
Joined: Jun 2002
Posts: 319
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From: NH
Re: tachometer signal wire In case anyone is interested...I found the signal wire in the Helms manual in the ABS section. This signal is used by the traction control system which my donor car had as an option and so I was able to tap into the signal wire there in a more convienent spot for me.
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