t5535

Ok, here is the problem. Someone swapped the trans and motor in my car and I am trying to go back but they cut a bunch of the wires for the ecu. The main thing that I am consintrating on is getting the 700r trans back in they put in a turbo 350 and cut the wires for the 700r. I have been looking at the wireing digram and cant find what controlled it. I have the ecm wiring laid out to where I can see everything. I will post some pictures of it latter today. there are quite a few cut wires on it. I would like to fix this harness rather then buying a new one. the car came originally with a carbrated 5.0 and a 700r trans. they put in a carbrated 350 and a turbo 350 trans and bypassed the hole ecm I mean the power wire for the ecm was even unhooked. my plan is to keep the carbrated 350 and put back in the 700r but I would like for the ecm to work as it should. Everyone on here has been allot of help so far on this trans am project and I thank you all for that. here is the wiring diagram that I have been working off of.


O ya and its a 87 trans am

hectorsn

I havent dealt with this for a while but I'm almost positive the only ECM controlled function of that trans is TCC (lock-up torque converter). Again, going off of memory there is a 4 wire square plug on the trans. Looking at the diagram, the four wires would be two for TCC control, one for the top gear switch and the other wire doesnt exist IIRC. Then you have the selector switch which looks like it has two wires. The ECM uses the selector switch and the VSS (which is from the dash) for idle strategies and throttle follower. The 4th gear switch is for TCC strategies I believe. So not having the ECM isnt going to significantly diminish the performance but it will have its annoying habits. Also I seem to remember that the 700r needed to have a properly operating TCC in 4th gear in order to prevent trans overheating. Something about it not operating the oil cooler circuit unless TCC was working or something? This may be totally wrong though as I havent studied this stuff for years. Not to mention the fact that I havent owned an auto trans car in about 20 years! Good luck with the project.

t5535

Ok here are some pictures that I just took.

this is the hole wire harness. as you can see allot of the wires are cut. all the plugs at the top where taped off lol. I don't know what any of them goto.


These are the ones that were taped off



These are the ones that are cut closest to the ecu




next in the line from the ecu





and the next batch that were cut on down the line

t5535

Do I need any of this to make the 700r work?

hectorsn

No the 700r doesnt need any ECM control to work. It is a throw back transmission, much like the turbo 350, that shifts through mechanical principles and not by computer controlled solenoids like modern transmissions. The only difference I see between the way these two transmissions work is that the 350 uses a vaccuum modulator and a detent cable to control throttle related shift points and that the 700r uses a TV cable. The only computer controlled item on the trans is the lock-up torque converter function which is not needed for shifting the trans through the gears. Like I said before though I believe you need for the lock up to close in overdrive in order to have proper transmission cooling. This you can do with various kits or switches and relays and dont necessarily need to have the computer do. Now as far as getting the ECM and wiring harness in your car to work, that wiring diagram is a great starting point. Just wire things up with the color codes it shows and any missing connectors will need to be replaced by salvage yard hunting more than likely. You might get lucky at a store that sells and makes all those connectors for GM. I think the site is weatherpack.com or something. Sorry I cant be of more help.

t5535

well to be honest I don't care about the ecu anymore just want the tranny to work right. I would rather just rip it all out lol. I want the overdrive for mpg ya know. Can I put on a tps and to sub what the ecu would do? and what about the speedo?

hectorsn

OD works just fine without any electrical control. If you have a turbo 350 you will need to get rid of the detent cable and have a properly adjusted TV cable for the trans to shift right. Its the lock-up converter (TCC) that wont work. I believe B&M sells a kit for controlling TCC. At this point though the topic is more transmission related than ECM related. Ask on the board related to trannys or do a search over there for better info. Like I said before, I'm a manual shifting mother-fella!

t5535

yup I would much rather have it manual lol. I think Im gonna rip out the stupid ecu. I don't need it anyway. the came stock with a 700r but someone swapped in a turbo 350 and didnt do it all that well they left the crossmember alone and chopped all the wires. from what I have been reading it shouldn't be all that hard to make it work right without the ecu.

vorteciroc

You may still have the original TH700R4 torque converter clutch wiring harness, or even the wiring harness and connector taped up. I did not see it in the pictures you posted.

This is what it looks like:


Its a four terminal white body Packard (P.E.D.) electrical connector, however it only will have three terminals installed. The connector will have a 0.8mm (18 awg) light blue wire comming out of the Engine Control Module through the passenger side fender grommet. The connector will have two other wires coming from the C207 wiring harness connector under the passenger side dashboard, left of the Engine Control Module. The second wire is a 0.8mm (18 awg) tan with black tracer. The last wire is a 0.8mm (18 awg) purple.

Ol' Caprice

Yo vortcIROC, and you rock! I am wondering where the 3 wires you mentioned in this post.....post? (connect) I have an 88 Caprice with a 700r and the wires you mentioned. but where to stick em? Please let me know. I have a 1227747 pr 1228746 ecm to use. Thanks!!!! JR