SatisTraction

iTrader: (2)

I have been reading up on where to connect my autometer tach and it seems to be hit and miss on it working. so where did you hook it up and what are your results?

thanks
chris

NHRAMAN

iTrader: (1)

can't remember which wire....AUTOMETER has a HELP/ASSISTANCE # on the back of box.

ghettocruiser

iTrader: (17)

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.

ls1_chevelle

iTrader: (9)

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.

NHRAMAN

iTrader: (1)

YUP...I remember now..had trouble at first because we had it in 8cyl mode...called A.Meter and they said 4 cyl mode...pretty weird.

67RSCamaroVette

iTrader: (63)

flipped the switches under the little orange sticker to 4cyl mode, white tach signal wire and it works like a charm.. wish my battery voltage gauge worked.

Kamin

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.

forcd ind

iTrader: (7)

at my age anything w/o a carb. is rocket science-lol
i have been printing out all these post so when i fire up my chevelle it will help me track down some problems (solutions)
you guys are rocket scientists!
thanks

Horsepwraddict

iTrader: (12)

some Autometers dont have a switch, they have wires that you have to cut (or not cut) according to your application. So if you cant find a switch, dont panic.

ghettocruiser

iTrader: (17)

Huh? What autometer gauges require you to cut wires to change their settings???? Older ones?

SatisTraction, Did you get it sorted out? If not..give us more details on what "hit or miss" means as far as it working...

J.

67RSCamaroVette

iTrader: (63)

my MSD window switch for nitrous required wires to be cut, little red and blue loops to change to 6 or 4 cyl

ls1_chevelle

iTrader: (9)

Lets drop your attitude. Its been hit and miss with many people. From a tight budget build to builds that total well over 100grand IE Steves infamous "Penny".

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

ghettocruiser

iTrader: (17)

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.

ls1_chevelle

iTrader: (9)

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

Rodder

iTrader: (2)

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.

lt4malibu

iTrader: (39)

why does it need to be in 4cyl mode? maybe thats why mine only reads 300rpm lol

ghettocruiser

iTrader: (17)

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.

SatisTraction

iTrader: (2)

thanks for the help. i have not fired mine off yet so I may be good to go. I have been waiting 10 weeks for Ricks Hot rod shop to build my gas tank.

IOwnCalculus

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.

ls1_chevelle

iTrader: (9)

Thats my thoughts. To me a 300 dollar tach should have the brains to tell if it needs to steal some juice from its 12volt source in order to amplify enough to make the tach work properly.

However I probably just gave an idea to some company that is going to make millions on it now.