Installing a tach on a 02' GP motor

Jae30001 · #1 07-05-2008, 09:12 PM

Quick off topic question.. Im trying to install a tach from GM Performance. It has a shift light however im not going to use it. I own a 1993 Pontiac GrandPrix. However.. I have a swap in it. It has a 3800 Serries II motor from a 2002 Pontiac Grand Prix, not super charged. (Motor trany, wires, all). Pretty much making this a 02 gp. Now my question is.. Where do I connect the signal wire to, to get acurate rpm reading to my tach meter.

Thank you very much, i have been searching everywhere!! This seemed like the best place to do it.

tblake · #2 07-05-2008, 10:18 PM

Wow, what a swap!!!!!!!! Nice Job!

Man, I cannot remember what color the wire is, but you should be able to get the tach signal from one of the wires at the ignition module. I think it may be either white or purple with a black stripe. You can set a multimeter to read AC voltage, place one probe on ground and the other on one of the wires at the ICM. you should be able to find one that will give higher voltage as the motor is revveed up. Maybe want to slide back the ICM plug weather proof plug so you dont have to poke a million holes through it.

Otherwise if you could get a diagram of the PCM, you should be able to get the Tach signal from there too.

Jae30001 · #3 07-05-2008, 10:28 PM

Thanks for that fast response!! The thing is.. I cannot find schematics anywhere!! Yes it was one heck of a swap!!
Was hoping to find a stock sc to bolt on, but i have had no luck doing so. Maybe i will upload some pictures..

If you could find a diagram for me, that would be awesome!

Thank you

tblake · #4 07-05-2008, 10:43 PM

Ok, I'll make you a deal, I'll get you the PCM schematic (providing you got the 2002 PCM from the doner car) if you upload a few pictures of the swap for us to drool at.....

PS, the 3800 II SC supercharger will not bolt up to the 3800 II NA motor without also swapping the lower intake manifold and the heads. (but you probably already know that). You can get a supercharger kit from zzperformance.com for the 3800 II NA motor. I think it includes everything to add a supercharger to the Naturally Aspirated 3800. I think a few forum members have tried it with success. Sure would be nice to have a good tech article with pictures of a member doing this mod.... (hint hint)

I'll get your schematic......

tblake · #5 07-05-2008, 11:08 PM

Ok, here's what I've got. If you need the other 3, let me know. I'm not sure what wire to use for your tach, but one of the other more electrical savvey forum members should be able to look at this and help you out.....

Engine Wiring Diagram 1 of 4

Jae30001 · #6 07-05-2008, 11:12 PM

Alright thanks, I will look at that in a minute and i will let you know if i need more!!

I am currently uploading pictures of the car so everyone can see! Gimme a few minutes!

HotZ28 · #7 07-05-2008, 11:26 PM

This one is easier to see! Look @ terminal E.

Jae30001 · #8 07-05-2008, 11:46 PM

Hey, I uploaded Pictures: here they are

http://www.automotiveforums.com/vbul...80#post5766680

let me know what you think, thanks again for the help guys!

Jae30001 · #9 07-06-2008, 10:25 AM

Awesome. Just hooked it up it got a good signal.. However.. It's a 10k tach from GM performance.. Main reason i was looking to get it is because of the current stock tach failure. While in park.. it seems to be working smooth, except idle it seems a little high, however rev limit seems to read 6k. Now while driving its a whole different ball game! Flooring it leaves the tach at 8-9K untill i let off. I have had this same problem with the stock tach. Man is this a tricky one!!

Everything works great except the tach, and Fuel gauge!! The fuel is off due to different fuel tank sizes, and fuel sending unit.. The tach.. well im not sure yet.. but hopefully i can figure this out!!!

Everything down to the powerlocks, windows and sun roof works!

tblake · #10 07-06-2008, 11:15 AM

Stupid question for someone with your intelligence, but you did get the PCM from the donor car, right?

Jae30001 · #11 07-06-2008, 11:19 AM

Yes i did

Jae30001 · #12 07-07-2008, 01:22 PM

I currently have a 99' Monte carlo pcm.. seems the gp wouldn't start.. they are pretty much the same.. interchangeable ;-)

I do have the donar car PCM aswell...

The wire job i pretty much had down.. however, buddy did most of the front end wire, as i focused on interior.. The PCM is located on the passenger side.. rather than the front. The stock tach is outta wack aswell! i just worked an overnight shift.. so im delerious right now.. Hope that helps some!

THANKS!

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