where did you connect your autometer tach & is it working? LS1
#3
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On my 99 LS1...Im pretty sure its hooked to the #10 pin...whire wire. Its the tach signal wire. Cant remember which PCM connector it was on (red or blue)... And now that I think about it, I may have grabbed it at one of the smaller plugs (blue or white). Basically anywhere that the tach signal gets sent. Its used in a couple different circuits if I recall correctly.
Either way...my tach works perfectly. Make sure its set to 4cyl mode. Then, before going completely crazy, double and tripple check your grounds, power, signal wires to the tach, as well as their connections to the car. And I dont mean just look at them and see they are there and figure they are ok. Get a meter and test everything out. Wiggle the wires with the tester on them to see if you have a random, movement caused short.
If all else fails, give autometer a call.
J.
Either way...my tach works perfectly. Make sure its set to 4cyl mode. Then, before going completely crazy, double and tripple check your grounds, power, signal wires to the tach, as well as their connections to the car. And I dont mean just look at them and see they are there and figure they are ok. Get a meter and test everything out. Wiggle the wires with the tester on them to see if you have a random, movement caused short.
If all else fails, give autometer a call.
J.
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yea pin 10 which is a white wire.
To get my autometer to work... I had to run a switched 12volt wire(so its hot when the car is running) with a 480ohm resistor and spliced it into the pin 10 white wire to get a strong enough signal for 4cyl mode. Works great now.
To get my autometer to work... I had to run a switched 12volt wire(so its hot when the car is running) with a 480ohm resistor and spliced it into the pin 10 white wire to get a strong enough signal for 4cyl mode. Works great now.
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people have problems using an autometer tach?
its not rocket science guys. switched power, illumination, a couple grounds, and the signal wire from the ECU. make sure its in 4cyl mode, done.
its not rocket science guys. switched power, illumination, a couple grounds, and the signal wire from the ECU. make sure its in 4cyl mode, done.
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Some times the ecu doesn't send a strong enough signal for not just autometer gauges but for every gauge on the market. So the 480ohm switched 12volt source has to get spliced into the tach signal from the ecu to make the signal stronger.
So before you jump to conclusions and think of yourself as a ******* super hero, think before you speak.
And yes, all of the older autometer tachs have 1 brown and 1 orange wire that looks like a loop from the backside. I can't remember which wire you cut to make 4cyl/6cyl
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Huh...Never knew that. Learn something new...
I also never heard of the switched 12v + 480ohm trick either... That sounds like a reasonable solution. But why would random LS1 PCMs not be able to work on an aftermarket tach?? I mean, obviously if that trick works, then it works. Just seems weird is all. But its definetly good to know!
J.
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Huh...Never knew that. Learn something new...
I also never heard of the switched 12v + 480ohm trick either... That sounds like a reasonable solution. But why would random LS1 PCMs not be able to work on an aftermarket tach?? I mean, obviously if that trick works, then it works. Just seems weird is all. But its definetly good to know!
J.
I also never heard of the switched 12v + 480ohm trick either... That sounds like a reasonable solution. But why would random LS1 PCMs not be able to work on an aftermarket tach?? I mean, obviously if that trick works, then it works. Just seems weird is all. But its definetly good to know!
J.
Its a very good question as to why. I'll give an example. When I first had my harness done by a shop that is well known, my buddy sent his harness and ecu down with mine. We plugged everything in. He is running new autometers and I am running Defi gauges. His tach signal works great, and I got nothing. So I tried a stewart warner and a autometer to no avail.
After months of searching, a came across the switched 12 volt source and 480ohm resistor and it did the trick. No idea why some computers throw a weak tach signal, I just know that "it works" haha
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I believe the tach output from the PCM (meant to feed the cruise control module, not a tach) is 5V at the peaks. That's enough to trigger some tachs but not others. Adding the resistor to +12V pulls up the voltage high enough to be detected by the tach. The exact value of resistor need will depend on the internal resistance of the tach and PCM and the sensitivity of the tach.
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Yeah but it doesnt just go to the cruise unit. It also sends the tach signal to the tach iteself. I think thats one of the few gauges that doesnt rely on the serial data alone for its info...right?? Or am I mistaken. I remember finding white tach output wires in a few places when I was sifting through my harness.
It still doesnt make much sense to me... I would think that most aftermarket gauges would use the power input to "amplify" the signal so that it can read it. But Im sure I dont know all the inner workings of newer elec. tachs. haha. So Im probably just blowin smoke.
Still interesting why it works with one PCM but not another from the same year/model car.
J.
#19
For whatever reason, GM programmed these computers by default to output a tach signal similar to what a traditional tach would consider a four-cylinder signal and not an eight-cylinder signal. There is a setting in the computer that can be changed if you must use an eight-cylinder tach, though.
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Yeah but it doesnt just go to the cruise unit. It also sends the tach signal to the tach iteself. I think thats one of the few gauges that doesnt rely on the serial data alone for its info...right?? Or am I mistaken. I remember finding white tach output wires in a few places when I was sifting through my harness.
It still doesnt make much sense to me... I would think that most aftermarket gauges would use the power input to "amplify" the signal so that it can read it. But Im sure I dont know all the inner workings of newer elec. tachs. haha. So Im probably just blowin smoke.
Still interesting why it works with one PCM but not another from the same year/model car.
J.
It still doesnt make much sense to me... I would think that most aftermarket gauges would use the power input to "amplify" the signal so that it can read it. But Im sure I dont know all the inner workings of newer elec. tachs. haha. So Im probably just blowin smoke.
Still interesting why it works with one PCM but not another from the same year/model car.
J.
However I probably just gave an idea to some company that is going to make millions on it now.