Okay guys I am pulling my hair out I picked up this 1989 Ford Superduty with a manual transmission currently it has an ECU located in the firewall come to find out at one time this truck was a automatic so I guess my question is how do I bypass the ECU in order for everything that ran through it to work properly?
What all does run through it?
thanks in advance anything would help

 

you do not need to do anything. that is a trans control module.
the engine is 100% mechanical, so the trans control module has absolutely no effect on the truck now that it has a manual trans in it.

 

so does that mean the only thing I have to bypass is the wires for the RPM gauge?

 

nope. tach signal comes from the sending unit on the timing cover which is probably unplugged, or bad. trans computer gets it's signal from the tach, not tach getting signal from trans computer.

 

^^ this ^^

The tach sensor on these is apparently pretty common to fail from what I've read. They're not cheap either. Someone found out you can use a cheaper sensor and modify it to fit. I can't remember what it's called. It was a Honeywell sensor of some kind.

 

if I bypass the computer as shown in the picture my tachometer Will work

 

Also, I saw your other post. You won't be able to pull codes in one of these. Everything is mechanical and there's no computer to tell you what's wrong (or to cause issues either).

Luckily the guys around here are pretty smart and helpful. Also, these trucks are pretty simple too which definitely helps!

 

yeah there is a lot of knowledgeable people on this site it's pretty awesome

 

interesting. if it works, then go for it!!!

i will admit i do not know very much about the electronic auto transmissions, all my trucks had C-6 autos except for the 88 which had the 5 speed before the transfer case let loose in 05 at 375,000 miles and took the trans out with it.
that was when i put a C6 in the 88.