How are you guys getting your tachometer to work? I have all of my gauges working but the tach, because my '00 PCM does not have a tach output, it uses serial data to the Instrument cluster.

I have a hunch that the RPM signal the PCM sends to the ABS/Traction module might work, but was wondering what everybody else did. I don't want a big aftermarket tach mounted to the dash either.

TIA

 

not have a tach output? sure it does! thats how everyone gets aftermarket tachs, shiftlights, window switches, ect to work.


its the C105 plug... pin G.. white wire... #10 on the PCM.

its suppost to go out to the brake or traction control or somthing... but its a tach pulse.... a 4cyl tach pulse.

get a converter to double it into a 8 cyl tach pulse for the stock tach, or get a aftermarket tach, and set it to 4cyl mode.

 

I had the right circuit, but wasn't sure because its a low voltage signal (5 volts). I was expecting it to read 50% since it puts out a 4 cylinder signal, but the PCM puts out a 0-5 volt signal instead of a 0-12 volt signal, making my stock Tach read zero. I installed the dakota digital SGI-8 and that fixed it.

 

What output did you use on the SGI-8 and what did you set the 10 switches to??


Thanks!


**Old post, sorry to bring it back up!

 

you dont need a SGI8.. you can do it now by directly connecting it to the tach..

then you can use HPtuners, LS1edit, or EFIlive to set the tach output to 8cyl mode... or 6cyl mode if you have a V6 tach..


arnt advancements nice? couldnt do it last year, but you can do it now.

 

What about Tunercat?? Can it adjust the tach output?? That's what we're using to tune it... we already have the speedo working w/out an adapter b/c we changed my tire size and rearend ratio in the PCM. I unhooked the SGI-8 for my speedo last night and just hooked the input/output together and it works fine. Now if I can just get my tach working right.


Thanks!

 

ive never used tunercat on a LS1... so i donno..

 

You sure you are using Tunercat and not LS1Edit, or HPTuner? Tunercat isn't for OBDII, just for LT1, Truck, and some late model F-body cars.

 

Yes it is tunercat its just like the tunercat I used when tuning my old TPI motor... a friend has the LS1 tunercat though... no issue with it whatsoever... apparently not many people know they offer it. He said he can get it for my '04 GTO as well. Works for me

 

isnt LS1 tunercat = EFIlive??

 

EFILive apparently will use the Autotap for OBDII, the company is based out of New Zealand

 

the autotap?? will use?

its already out.... has been for awhile.


athough i use HPtuners.

 

I'm confused as hell right now... all I know is we used Tunercat and Autotap I believe... I'm checking with my buddy who is doing the tune to see if we can just change the tach output signal from the PCM. Isn't it weird that my tach just drops once I hit 5k?? Anyone else experience this before?? It's kinda similar to what my tach did when I had the 355TPI in my car with a MSD6A box... I had to end up using a $25 MSD tach adapter to get it to work right... weird

 

I ment the Autotap cable, sorry

just got an e-mail back from Tunercat, and yup, they have a tuning program for LS1's that is not VIN locked like Edit is, just have to get the definition file for the motor you are working on, and it's very resonably priced.

 

Yep, just what we're doing