Tach Wiring Troubles.
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Staging Lane
Joined: Feb 2006
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Tach Wiring Troubles. So I recently installed a 5 inch tach in my car. Thought the install was pretty straight forward and rather easy. However, as I go to fire up the car I find two things wrong:
1. The tach response is half of what the RPMs actually are. That is say my stock is at 3k the tach is only at like 1.3K. I wired the tach speed wire with a splice to the #10 white wire in the PCM. Also, this mechanic I was talking to said that you should never connect this wire to the PCM as it may f-up your comp. I have no clue what he is talking about all the install guides I read as well as the older threads on here hooked it up there. Plus I don't know where else you would hook up the tach speed wire if not at the pcm. But, what are your thoughts? Obviosuly it is responding since it goes up some RPMS just not flawlessly. What could be causing this? Where did I go wrong with my wiring.
2. Okay, this one is kinda funny. For the lighting I hooked the tach up the dark green wire that controls the console lighting so that I could adjust the brightness on the tach. Well now the tach lights up only when I turn the console lighting all the way down, and vice versa. I really would like to have both lit at the same time, lol, so please offer your thought on WTF I did wrong and how the problem can be fixed.
Oh, please don't flame me or anything this was my very first attempt at doing any sory of wiring work on my car, and until I started it I thought I had done a pretty good job.
Thanks for the help as always your input is invaluable.
1. The tach response is half of what the RPMs actually are. That is say my stock is at 3k the tach is only at like 1.3K. I wired the tach speed wire with a splice to the #10 white wire in the PCM. Also, this mechanic I was talking to said that you should never connect this wire to the PCM as it may f-up your comp. I have no clue what he is talking about all the install guides I read as well as the older threads on here hooked it up there. Plus I don't know where else you would hook up the tach speed wire if not at the pcm. But, what are your thoughts? Obviosuly it is responding since it goes up some RPMS just not flawlessly. What could be causing this? Where did I go wrong with my wiring.
2. Okay, this one is kinda funny. For the lighting I hooked the tach up the dark green wire that controls the console lighting so that I could adjust the brightness on the tach. Well now the tach lights up only when I turn the console lighting all the way down, and vice versa. I really would like to have both lit at the same time, lol, so please offer your thought on WTF I did wrong and how the problem can be fixed.
Oh, please don't flame me or anything this was my very first attempt at doing any sory of wiring work on my car, and until I started it I thought I had done a pretty good job.
Thanks for the help as always your input is invaluable.
Thread Starter
Staging Lane
Joined: Feb 2006
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yea its an autometer. as for the 4cyl stting, their directions said if you have 8 cyl then no modification is needed to the wires out back and only if you have 4 or 6 cyl do you cut those wires. I only wanna ask to be sure because I have to cut the wires.
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I have a 5 year old AUTOMETER 5' Tach and I had to cut a wire..not sure which one..its all taped and I put covering tube on it so SORRY, I can't just go look..CALL THEM.
Originally Posted by adavypromos
yea its an autometer. as for the 4cyl stting, their directions said if you have 8 cyl then no modification is needed to the wires out back and only if you have 4 or 6 cyl do you cut those wires. I only wanna ask to be sure because I have to cut the wires.
take your lighting wire that comes off of the tach, take out the IPDIMMER fuse, and plug it right into your fusebox and put the fuse back in.
red goes to 12volt switched on if i remember correctly and ground goes to a good ground.
and BTW, i hooked right into the white wire coming out of the pcm, no error codes, everything is cool
Thread Starter
Staging Lane
Joined: Feb 2006
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Alright so I do have to cut both of the wires. That is so strange their instructions specifically state: 8 cylinder No modification necessary. Thanks for the help, I am going to call them tomorrow just to be 100% sure and I will let you guys know the results after I am done fugging with it.
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ill bet my life on it. heres why my friend- LS1s dont use distributors. they use a coil pack per cylinder so thats why you must use 4cyl mode. DO IT i would not lie to a fellow LS1 guy. look at my member feedback, "VERY TRUSTWORTHY" lol
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From: South Alabama
Originally Posted by adavypromos
Alright so I do have to cut both of the wires. That is so strange their instructions specifically state: 8 cylinder No modification necessary. Thanks for the help, I am going to call them tomorrow just to be 100% sure and I will let you guys know the results after I am done fugging with it.
Been there-Done that.
The LS1 creates a double electrical pulse per cylinder, makes it appear to be a 4 cylinder to all attached electrical monitoring devices. Same will be true for a shift light.
Like I said before - set it to 4 cylinders if you want it to work right.
Originally Posted by Weezzer
Been there-Done that.
The LS1 creates a double electrical pulse per cylinder, makes it appear to be a 4 cylinder to all attached electrical monitoring devices. Same will be true for a shift light.
Like I said before - set it to 4 cylinders if you want it to work right.
The LS1 creates a double electrical pulse per cylinder, makes it appear to be a 4 cylinder to all attached electrical monitoring devices. Same will be true for a shift light.
Like I said before - set it to 4 cylinders if you want it to work right.
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From: Vancouver,[KITSILANO].B.C. Canada *WestCoast*
Originally Posted by 98TADRIVER
ill bet my life on it. heres why my friend- LS1s dont use distributors. they use a coil pack per cylinder so thats why you must use 4cyl mode. DO IT i would not lie to a fellow LS1 guy. look at my member feedback, "VERY TRUSTWORTHY" lol
Thread Starter
Staging Lane
Joined: Feb 2006
Posts: 87
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It works you guys are the best.
Alright, I dont think I will ever listen to another mechanic again. I was so scared when he said that I fu$$ed up my wiring and was going to ruin the PCM (especially since this was my first time doing wire work). But obviously he didn't know WTF he was talking about. Thanks guys.
Any ideas on why the light comes on when I am dimming the dash instead of the other way around? I would really like to be able to turn up/down the light as opposed to it being on all the time, thanks for the help in advance.
Alright, I dont think I will ever listen to another mechanic again. I was so scared when he said that I fu$$ed up my wiring and was going to ruin the PCM (especially since this was my first time doing wire work). But obviously he didn't know WTF he was talking about. Thanks guys.
Any ideas on why the light comes on when I am dimming the dash instead of the other way around? I would really like to be able to turn up/down the light as opposed to it being on all the time, thanks for the help in advance.
