Another ATX --> MTX question

[rubydist]

I searched, but cannot find the answer to this one... (most of these threads seem to have been lost in the crash...)

I have a good 92 3.0/mtx on a subframe that I plan to put into a 95 atx that threw a rod. I also have a 93 mtx car (also w/ bad engine) for parts, so I can harvest anything I need. I would like to use the 93 mtx pcm, and I have some wiring questions.

1. can I just plug in the mtx pcm and use the 3.0 engine wiring harness, or are there other wiring changes I need to make in the engine compartment?

2. how do I wire the clutch interlock? do I jumper the neutral switch connector on the console where it used to plug into the atx trans selector, or is it different?

3. any other wiring changes I need to make?

Thanks in advance.

 

[Shoaz]

I searched, but cannot find the answer to this one... (most of these threads seem to have been lost in the crash...)

I have a good 92 3.0/mtx on a subframe that I plan to put into a 95 atx that threw a rod. I also have a 93 mtx car (also w/ bad engine) for parts, so I can harvest anything I need. I would like to use the 93 mtx pcm, and I have some wiring questions.

1. can I just plug in the mtx pcm and use the 3.0 engine wiring harness, or are there other wiring changes I need to make in the engine compartment?

If you keep the 3.0 Engine and 3.0 PCM together you'll minimize or eliminate any wiring changes needed for the engine. There are some issues with plugging into the dash harness, but I don't think they're huge.

2. how do I wire the clutch interlock? do I jumper the neutral switch connector on the console where it used to plug into the atx trans selector, or is it different?

That's probably one of the dash harness issue's you'll need to deal with. The switch on the clutch will come with the pedal set that you move from one of the MTX cars, and that switch will need to get wired into the start enable circuit. I think an EVTM manual is going to be your friend for stuff like that.

3. any other wiring changes I need to make?

Thanks in advance.

Probably.

 

[craygo]

I did a swap on my 94 ATX -> MTX I. The doner car was a 92. I had to swap the wiring harness from the headlights to the dashboard because of differences with certain plugs and clips. So I would use the the wiring from the 93 mtx.

The main harness connector on my 94 was square while the 92 was round. This was the reason I had to change the dash wiring as well as the engine harness.

Also I didn't have an issue with the nuetral switch since I swapped out the wiring harness in my dash with the harness from the 92 dash.

Needless to say I have a good grip on the wiring of the SHO dashboard.

So stick with the wiring from the 93 and up to minimize the problems. The 92 harness was leftover from the first gen cars. When the 93 cars came out they reworked the harnesses.

Ray

 

[rubydist]

Does the mtx pcm have the 4k rev limiter when the clutch is depressed, or can I just jumper the clutch interlock switch? I know on some of the newer pcm's, it needs to see that switch open and close, so on some you cannot just jumper the clutch interlock.... Anyone know for sure?

 

[Shoaz]

The MTX does not have the 4krpm rev limit issue, which was for the torque converter in the ATX.

The clutch interlock is nice to have from a safety standpoint so that the car can't either bump or bump and start when the starter is engaged in gear. It won't be difficult to wire the switch on the pedal assembly to the interlock wiring in the PCM harness.

 

[rubydist]

OK, so the plan to use the mtx engine and front chassis wiring harness had to be aborted when I discovered that the 95 dash harness does not plug into the 93 front chassis harness - the plugs are the same size, but they are keyed differently because they are populated differently..... among other things, I've found that the 94-95 a/c system has both a low pressure cycling switch and a high pressure switch, while the 93 and earlier a/c system has only the cycling switch; and the 94+ alternator is a 3 wire plug while the earlier ones are only 2 wire plugs.

So, the new plan is to use all the 3.2 wiring and do the 'tricks' to get the pcm to think that the car is always in park and drive simultaneously (as shoaz and phoenix have described elsewhere). This will also require modifications to the a/c wiring, as the dryer & cycling switch is in a different place and will require finding a place to mount the atx cruise control module...

 

[Kens1992mtxSHO]

Why not go all the way and do a 3.2 MTX swap while you're doing most of the work?

 

[rubydist]

Cause I bought the car w/ a dead 3.2 and I have a good 3.0 w/ trans waiting for a home.

 

[Kens1992mtxSHO]

ahhhhhhhhhh, gotcha Good luck

 

[Phoenix]

You can do that OR , use the 3.0 engine harness mated to the 3.2 dash harness.

That is the setup I currently have. But it takes several hours to cut and re-wire the big connector. You will also need BOTH diagrams books EVTM of both donor and receiving car to mate all the wires correctly. And the result is below. Plus the 3 wire alternator is easy , ditch the middle wire of the 3 wires and plug it. It works.

 

[rubydist]

That's one of my issues, I have a 94 book w/ wiring diagrams, which I believe is correct for 95 also, but is not correct for 93, so I can't do the matchup from one to the other. Plus, I really, really want to avoid the spagetti look under the hood.

I already figured out the alternator wiring (the middle wire is unused and just terminates in the harness), and (thanks to a link provided earlier) I know how to make the pcm think the car is in park and drive at the same time.

Now I'm working on wiring for the a/c and finding a home for the cruise control servo. How important do you think that engine damper is that fits on the strut tower on the driver's side???

Ken, the original 3.2 threw a rod - the p.o. claimed it never knocked, but one day his wife was driving down the highway when she heard a large 'bang' and everything stopped. Part of the #5 rod had decided to come out the front side of the block/pan. And, since there is barely room for the crank counterweights when the piston is up, you can imagine what happens when its still down...

 

[rubydist]

Success! Fired it up tonight, and it took right off. I just need to put the interior back together, put on the front wheels, and hook up the exhaust and it'll be back on the road again!

On a side note, during the time I was planning on using mtx wiring I sold the atx cruise control servo, so now I'm in the market to buy one...

 

[yzstud]

mark down another mtx swap
good job man!! :wave:

 

[38SHO]

word that was fast!

 

[rubydist]

OK, who knows how to get the old atx shift cable out of there??? The manual simply says 'pull back the carpet and remove the bracket', but as I look it seems that the bracket is buried under the heat plenum that runs back to the rear, which has several fasteners and would require removing the carpet and front seats to loosen..... is it possible to remove that bracket without disassembling the whole interior? If so, can someone provide another hint or two?

 

[yzstud]

just snip it at the shifter and pull it through the engine bay