Zorro O

Hi guys, I have a 1979 C3 running TPI. I would like my glove box back! I know others are or have run TPI where did you mount the ECM?

Thanks
Zorro

rebel542

I extended my harness several feet and shoved ECM, fuse block and ALDL in storage compartment behind passenger seat.

Amorget

My plan is a custom wiring harness to mount the ECM is the stock 81 place (near the battery). However, you could go with a C4 Corvette ECM which is watertight and mount it under the hood.

Rotonda

I am running a late C4 waterproof ECM mounted in the engine compartment on the back side of the left hand inner fender. I used the original bracket and bolted through the fiberglass from the wheel side. it works well and is completely out of the way.

Unfortunately, if you have already installed your TPI and harness, the waterproof ECM has a different pin/plug arrangement from the non-waterproof. The two harnesses/ECM's are not compatible. I got my harness from Street & Performance, built specifically for the waterproof ECM.

mrvette

Water resist or not, I like my electronics cool and dry, do the pass side storage bin, I have a map pocket in my '72, so fabbed a couple brackets and hooked 1227730 up behind the map pocket, plenty of room.....

Zorro O

You guys are great! I learned more in a handful of post, than I did in a year and a half of reading manuals and staring at the problem. I have been in the battery compartment hundreds of times, I never notice the space under the compartment door frame toward the drivers seat. Now I need to find the parts to build a five foot extension for the ECM wiring.

Thanks
Zorro

Amorget

I see 2 options for it. 1) buy a length of whatever color wire or 2) go over to Pick N Pull on Old 99 and grab the ECM harness for some mid 90s GM vehicle and use those wires to extend the harness. I'll look for a car that has the ECM under the rear seat or at least under the dash. You won't get much wiring from a car with it mounted under the hood. Any Thirdgen F-body would make a good candidate, too.

The GM harness would allow you to extend it using the correct wiring colors.

Either way I would solder and shrink wrap to do the actual extension.

Zorro O

Amorget, The thirdgen F-body is a good idea. With the plugs on one end all I would need to find are female plugs for the other end and it would be plug and play. I might be able to get them from an old ECM. I defiantly want to keep the color coding on the wires correct. A long time ago I bought a 70 Z28, it was a rare car, clean and ran great. The one problem it had was at some point it had a wiring fire under the dash. The owner had replaced the dash and all the wiring (every bit of it) with orange wire. Being young and dumb I thought no big deal. It was a nightmare!
Zorro

Amorget

Which ECM do you have? A 730 or a 165? They use different plugs and were available in different years.

Finding the female end isn't as easy as it sounds... I am not sure anybody makes them and the ECM end is soldered to the circuit board making it not very useful.

Zorro O

I can't get to the ECM right now so I do not know what number it is. You are right about the ECM connectors, it would be easier to just find aftermarket plugs or just splice every thing. I hate splicing. I have a new dash sitting here and I plan to move the ECM when I install it after the first of the year, so I have time to think this over. Thank you for pointing out the problem with using the plugs from an old ECM, you saved me from wasting time on that.

Zorro

Amorget

It's pretty easy to tell which ECM you have without actually getting to the ECM. A 165 ECM will have a MAF where a 730 won't (it's a "speed density" ecm). If you don't have a MAF sensor somewhere in the intake tract then 99% sure you have a 730. If you have a MAP sensor, then basically 100% sure you have a 730.

To note, since you'll be doing this after the 1st of the year, PnP will probably have a 50% off sale around Thanksgiving, so that's a good time to pull the harness and save a few bucks.

Zorro O

Yup, it's got a MAP sensor. Do you have an web address for PnP?

Zorro

Amorget

http://www.picknpull.com/

However, www.row52.com is the best place to check their inventory. For a 730 ECM it will only be 90-92 F-bodies, however the V6 version will work. The J-bodies used the same ECM, so you could pull the harness from one of them. I am not 100% sure what year J-Bodies used the 730, but it's probably in the same range as the F-bodies. The harness length won't be that much different I don't think.

Amorget

P.S. I'd love to check out your car sometime. I live up on Camano Island and like I said, I am installing a TPI engine in my wife's 81 probably next winter so I'd like to check out another TPI C3

Zorro O

Sounds good, wait till I put it back together. Camano is a nice drive.

Zorro