Wiring opinions needed

[supraficial]

Okay, so this is my first post on the forum, I've been searching for a few days on the issues I've been having. To start off, I bought this car from a guy in the army who didn't have time to finish the swap from the original 7mge to a 7mgte. Supposedly the engine has only about 90k miles on it, but it looks to be roughly treated. Many hoses and wires have been hacked. The car is an 86.5 with a 5-speed. Pretty sure it's the w58 from the searching. The ecu is not the correct for the car. It has the grey plugs and the harness seems very rough. The harness has many missing plugs and the engine bay is littered with a mix of yellow and grey plugged parts (ignitors etc) The cold start injector plug on the thermostat housing does not fit so that proves it is the later wiring harness on an older engine, correct? The a/c fan sensor and a/c fan switch wires were cut off of the thermostat housing as well. Many grounds are just hanging down, and the speed sensor off of the w58 was cut. My question and reason for posting is that I've been searching and I'm new to the forum and the car and just looking for some guidance. Should I get a brand new harness from tweak'd and ecu off of a member/ebay and end all the wiring headache? Or is what I have here salvageable from what you guys can see? Thanks for your guy's help, and sorry for the ignorance and jumbled post.

Here are some pictures I've taken in the tear down:

This was also plugged in one connector by the ecu..

The ecu that came in the car when I bought it

Pass. side engine bay w/ yellow plug resistor, loose hoses and plugs

Driver side engine bay with yellow resistor again but with grey plug. Also ignitor confusion, had a coil&ignitor from a 5m bolted in place but not attached to anything so put this one in that was in the trunk with other misc. engine parts

And lastly, the entire engine bay as it stood.

Like I said above, any help would be appreciated, I'm in this build alone so far because I havent been into the supra scene for long enough to make friends that know anything :1zhelp: I have found the tweakd harness and possibly a craigslist parts car with the harness (much sketchier, dont know if the harness is rotted) I searched, but I honestly haven't found a harness or car in as bad of shape. Thanks for looking :icon_bigg

 

[CyFi6]

Basically, you need to match the engine harness to the year of the vehicle. Since it is a pre-89 vehicle, you will want a pre-89 harness and ECU. The pre-89 harness and ECU both have yellow connectors. Easiest thing for you to do at this point is purchase a pre-89 yellow plug harness and pre-89 5 speed ECU, then swap the harness and ECU out. Depending on what year the engine is you may find that some of the connectors don't plug into some of the sensors (ex. water temp sensors, CSI switch), so you will just need to buy those sensors from a pre-89 engine and swap them.

 

[supraficial]

Thanks for the fast response. Would you recommend buying a new harness and ecu for $1000 or getting an entire parts car for $300 that cranks but doesn't run. Searched and might be the grounds.

 

[CyFi6]

Buy a used harness and ECU off of the classified section on this forum. You can usually get a decent harness without any broken connectors for around $100 to $150 that will work fine, and a used ECU for around $50 to $75 I would say. Brand new harnesses are not available from Toyota anymore and buying a brand new ECU would be pointless. Dr Tweak sells a brand new 7m harness that is custom made for around $1000 but if I remember correctly you have to supply him with the ECU connectors from a pre-89 harness if you need a pre-89 harness. New would definitely be the way to go on the harness if you can afford it but like I said you can probably get something half decent for around $150.

 

[Dan_Gyoba]

There is an exception tot he yellow plug harness. An '89 grey plug engine harness and ECU will connect to a pre '89 chassis and vise versa.

I have an '87 engine, ECU and yellow plug harness living perfectly happily in my grey-plug '89. There were 2 issues with this, both easily solved. One is that the ABS connector is different, but the wire colours are similar, so it was no problem to adapt this. The other is that the headlight line to the ECU is different for the electrical load idle-up. I simply re-wired the line from the #2 integration relay to the headlight relays, but there's a better way, which is to move the one pin at the ECU.

For '90 and up though the harnesses will not connect anymore. '89 was it's own special year, with a "mostly" compatible harness to the '86.5-'88.

If the ECU that you have is an '89 (Basically, can the chassis harness plug into it) then you should be okay as is. If it's from a '90 or later, then you can't plug it in, and you'll be way better off getting a compatable harness.)

 

[supraficial]

Well the previous owner didn't know much about the swap. He thought it was all correct as far as he knew, but like I said I think the engine is a different year to the harness because the CSI does not match up, and I can't seem to find a home for many of the connectors. I would much rather start fresh with a wiring harness in good shape (or just working condition) and put it together, rather than finding more and more loose ends in this one that isn't for the right year.

 

[akito]

Your best is to get a 87-88 and yes 89 engine harness and ECU and like others have posted you might need a few specific connectors due to the year differences. I have done the exact swap and ran into that problem first but this will be the most direct and cost effective for you. This will allow you to also eliminate the harness as the culprit, if in case it isn't, when you run into any electrical problems down the road.

 

[SC61 MK3]

Basically, you need to match the engine harness to the year of the vehicle. Since it is a pre-89 vehicle, you will want a pre-89 harness and ECU. The pre-89 harness and ECU both have yellow connectors. Easiest thing for you to do at this point is purchase a pre-89 yellow plug harness and pre-89 5 speed ECU, then swap the harness and ECU out. Depending on what year the engine is you may find that some of the connectors don't plug into some of the sensors (ex. water temp sensors, CSI switch), so you will just need to buy those sensors from a pre-89 engine and swap them.

^this...

I don't know why all the talk about the 89 weirdo harness when he said it was an 86.5, he just needs to get a yellow plug harness from a 86.5, 87 or 88 along with matching yellow plug 7mgte ecu. Most of the sensor plugs will match up to it, no matter gray/yellow plug sensor. Than just replace the ones that don't, i forget which ones they are off the top of my head. The for sale and wanted classified sections here is all you need to source all the parts you'll ever need

I actually have a harness out of my 88 turbo I'm about to put for sale if interested

 

[supraficial]

Yeah I would rather get the pre 89 ecu and harness for a piece of mind even if it makes the build only a little big easier, and sc61, I have been lookin around the for sale but mostly all I've found we're missing pieces, frayed here and there; is yours complete? PM me on a price