I'm sure there's one of you smart fellers that have seen my issue.
My tach on the dash died- won't read squat. when that happens, it sends the e4od in to default mode- stays in 4th gear, unless i manually shift the column. after doin a little reading i figured it was the rpm sensor that died. no way. replaced with a brand new one from the ford shop. still nothing.
i've got all kinds of wiring diagrams and can't figure out. Maybe narrowed my problem down to a ground issue- not sure.
any help would be greatly appreciated.

 

So does it only have 4th, reverse, and 2nd gears?

Here is information for you. David85 is one of the best for tranny Questions!

https://www.ford-trucks.com/forums/9...mp-mode-2.html

 

thanks, marshall- that link helped get me goin in the right direction.
however, i cannot find the teca module or the teca relay on my rig! both alldata and chiltons mention them, but nuthin.
can somebody help find it for me or find a picture of location.
if i can find the relay and use a jumper wire, i think i can track down my power issue.

any help is more than welcome- thanks guys!

yes, marshall, my truck only has reverse, 2nd and 4th gears. mpg's way down.

 

I've been trying to get help with my wiring for my tailights for ages. i dont know if anyone can help with finding things and tracking down problems. But i do know that your RPM gauge should have two wires. you can just follow them the old fashion way and run down where they go and how they work. then again my 84 is simple in the fact it doesnt have an RPM gauge.

 

the teca is also called the fipl ,im trying to find a pic for you.it on the drivers side of the motor it has 4 wires running to it and 2 bolts holding it in place and the mount is slotted for adjustment.it is mounted right around the second injector back.

 

the teca is tyhe brain of the transmission there is a relay that powers it up i am not sure where they are cause they rarely fail the fipl is a sensor that the teca reads as well as the speedo or vss and the tach sensor they all feed the teca and the teca makes decisions based on the info it gets from the sensors to determine shift points how much load youre putting on the trans

 

I found my problem. It was my EEC relay. I jumped with a wire, and it came alive! My tach is now workin and my tranny shifts again.
My beef is that everybody on here has different names for the relay. Teca, pcm, eec, ect. My truck is a 90, and though my chiltons mentions a TECA, there is no such thing as a relay by said name. I pulled up many wiring diags, and the only relay under the hood that has any thing to do with my issue is, in fact, called an EEC relay.
Now...with the jumper wire in, my problems are solved, kinda. I went to the parts store and got another relay- nothin! Im right back at the beginning. Wire=fix. New relay=same ol s&#t!
anybody?

 

Well, if you jumped the wire straight from the battery could it be a bad fuse?

Just kinda thinking out loud here.....

 

Did you test the old relay and the replacement before putting it in?
I'm trying to understand if the new relay is blown or of the problem lies in it not getting power from the ignition on circuit.

 

well, i figured out that i am getting power from the ignition switch, but not from the yellow fusible link, that should be hot at all times. the new relay is not bad, i gotta track down more wiring. in fact, my factory relay prob is not bad, either.
i'm runnin with just the jumper wire for the time being.

 

My next step would to be to check continuity between the relay socket and battery terminal (battery unhooked to be safe). Specifically the fusible link to start....

 

I have a 1991 F-250 4 x 4 Diesel, ecellent condition, accept we need a new, or rebuilt TECA, anyone know where to get one? Ford no longer supplies.

 

You will need to replace the power wire to the relay from the fusable link. they sometimes fail. rewire past the link with a in line fuse. there is a lable on the fusable link that should give you a idea how large a fuse you need. I had to do it on one of my fords before.

 

Thanks, yes we check for voltage, all good, the truck is in a reputable shop, for sure we need a TECA, but they can't find one, or a source to rebuild one. Guy's this truck just turned 100k, in perfect condition, but without the TECA, what? scrap the truck?<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

 

Where is this relay located? I didn't know there was a relay.

I have a short some where in my wiring also that cause my od light to come on once in a blue moon which I have to pull over turn truck off and start it up again and I'm good for a few weeks. I have also looked and looked also. I read another thread somewhere where someone claimed that the wiring going to the od switch in the column had a short and caused his to go into limp mode. I don't know just throwing it out there.