All aluminum 6.0 with computer, complete wiring, 4L60Ecomplete, t-case, running with fresh bearings: $1,800 or best offer.
Wish I had some extra $$$$ hangin around.
I'm hoping the 5.3 gives me at least a solid year but i would have been all over that If I lived in NC because it's what I really want in there. My 2500hd had balls for being stock and I know I would greatly enjoy it in the TJ
I am finally finishing up a few small details from this swap tonight.
I am extending the wiring for the obdII connector inside te can, wiring the MIL to the dash and hooking up the tach.
When I had the ECU programmed I had the tach output signal change to a 6 cyl. I temp hooked it up last night and it works but it is off 300-400 Rpm's. I believe I have found a way to adjust the stock tach fairly easily. Ill post more on that when I get it going.
One goal that I wanted with this swap was to keep all my original gauges. Why? Who knows.
Wiring the speedo, oil, coolant temp has already been covered. I believe on page 22, in my post covering the wiring.
This left me with the MIL light and the tach.
This is fairly easy. Jeep ECU provides ground to activate the MIL light and so does the GM ECU. You can find the MIL light wire at the back of the Tach wiring harness. You are looking for the black wire with a pink tracer. Simply wire the GM MIL wire to this wire. Thats it.
This takes a little more work.
First you need to find the wire, it is also located behind the Tach wiring harness. You are looking for the light grey wire with a purple tracer. Wire you GM tach wire here.
Now there are a million ways to do this. You can get a dakota digital box and convert the signal to what the Jeep tach wants to see and find tune it to get it dead on balls. You could also run an aftermarket tach but that doesn't get me where I want to be and both of those options cost money. Which by now in the swap we are all broke.
This is what I did.
I had my GM ECU programmed to output a 6cyl signal. But you don't have to too as you will see. I was able to adjust mine to with in 100 rpms. Also since my ECU is putting out a 6cyl signal I didn't need to change out the resistor.
Only info here I found to be wrong is that the pot only allows you to adjust for about 1000 rpm not 2000. But it worked for me with the output set at 6cyl because I was only out 500 rpm to start with.
Originally Posted by BigBlkYJ 355
Well after numerous people told me it could not be done, and everyone else told me to get a "monster tach" and bolt it to the dash, I finally got frustrated with it and sat down with a pen and paper to figure this stupid thing out. For those of you who care this is what I found:
The Jeep tach is controlled from a 12v pulse signal that is normally emmitted from the ECM when the #1 cylinder fires. This pulse is then transfered into a small circuit board which is attached to the stock tach. This circuit converts the pulse into a signal in which the tach's needle can read, and not show an erratic reading. The new small block or whatever you installed will give this signal from the distributor, coil pack, or msd tach output in my case.
On the circuit board there is a small Pot. (variable resistor) that is rated from ~3.0 ohms to ~ 10,000 ohms. This is an adjustment for calibration purposes that came in really handy when trying to figure this out. Basically for every 10,000 ohms taken away from the IC's ground (which is what the pot is doing) you lose around 2000 rpm on the tach's reading.
There is a small resistor attached in series with the pot. that is actually the nominal setting for the tach, and what i changed to make it work. That resistor is ~15,500 ohms on a meter. Well like i said for every 10,000 ohms dropped, you lose 2000 rpm, but remember you also have the ability from the pot to adjust 2000 rpm up or down.
I removed the small resistor and added one that is ~5600 ohms in its place, now dropping the lowest possible setting from ~2000 rpm to almost 0 rpm @ idle.
But remember, you can now adjust the rpm back up using the pot. So get yourself a portable tach, or dwell meter, and start comparing the needles. You can see in the pics i added a hole in the top of the gauge cluster to easily adjust the tach.
Start by removing the 3 screws that hold the gauge into the cluster.
Next, remove the 3 screws that hold the actual gauge needle to the circuit board. Note the 2 red areas, these are the spots that have to be unsoldered and re-worked.
This is the resistor installed with some pigtails added on because i used an old resistor i found in the box of about 10 million i have. Yes it is old as hell i know. Location R7 is where the small resistor was taken out.
This is the pot. that you will need to adjust later to make the reading correct.
This is a pic of the hole i drilled into the gauge cluster so that i can adjust it with the tach in place and the engine running.
Sorry for the long read, but to anyone who has gone through hell like i have to make this work, its worth it... :sonicjay:
This should be entered into some sort of jeep swap bible :tonka:
You need an OBD2 reader to pull the actual rpms from the GM computer. After you get it adjusted where you want it throw a piece of tape over the hole in the tach housing and reinstall. The Jeep tach isnt a fine instrument so best you can do is get it close. At idle Im out 50-75 rpms and at 2k Im out 100-150. But my ECU has a rev limiter so it isn't a crucial adjustment.