Diagnosis hell pls help

[IdiTrev]

90 7.3idi dually. dually is in limp mode currently. It sat for a while because i didn't have time. im about to swap a vss in as I had already been planning too as it tested in the 1700 range instead of 1200-1500 because it originally got parked in limp mode and I lost speedo while it was parked apparently along with my brakes blah blah blah but the real problem is I cant get my code flashouts and im trying to figure this out desparately. I have a scanner. The cheapo innova. I've tryed also just trying to use a test light and tryed watching the check engine light but the scanner won't communicate and the check engine light isn't working. I know it used to but now it won't light up at all even for the split second when you first turn the key on. I want to fix this so I can get my code flash out but unsure how to proceed I've been scavenging all the forums for hours upon hours and havnt found anything specifically about this particular problem except one guy with a similar thing going on who never figured it out. I tryed to order another tcm and when i swapped it still the same limp mode and no CEL code flashout. I have tryed cutting back the wire a lil for fresh wire and repinnig the EEC IV connector to see of it was just bad connection because those ends did look a bit corroded and I got nothing still. I tryed to see if maybe the bulb looks burned out for CEL and pulled front of dash off to look at bulb but it doesn't look bad. Looks just the same as the others next to it that all work. Once I figure out gettin my fingers in there I was gonna try and swap for another bulb to test but i suspect my problem is elsewhere electrically. I have questions. Does the eec iv plug go straight to the tcm. Does this CEL light just go through a plug at back of cluster and that goes to where? Straight to the tcm plug? That is the one wiring schematic I havnt found that I needed to know what wire colors im looking for and my pathway. Anyone have any ideas or advice its appreciated gettin super frustrated cause I can even use diagnostics for my limp mode cause there's an issue with diagnostics to fix lol Thanks.

 

[IDIBRONCO]

I'm no E4OD expert, but, after swapping the TCM, did you try unhooking the batteries for a while to clear the codes?

 

[IdiTrev]

honestly batteries have been disconnected multiple times while doing different work on it and when i swapped the tcm i wouldve thought it would've cleared the codes since that's the only real computer and being disconnected to swap them. I didn't think they would be stored in the psom? it all comes right back though on a new tcm. I disconnected the batteries after working on it earlier so i suppose I could try it again cause it's been a couple hours but that doesn't seem to be making a difference and Damn an idi bronco sounds badass man lol jealous. Ugh yea idk as far as this goes just to add more info when I repinned the the female square terminals in the eec plug the wiring looked good but I havnt traced the eec plug wires to where they go on the firewall tcm plug

 

[Old Goat]

This would be a lot easier to read and diagnose if you had good sentence structure.

Shame good Grammer is not taught in schools like it use to be.

Goat

 

[DaveBen]

You have got that right, Old Goat!

 

[IdiTrev]

This would be a lot easier to read and diagnose if you had good sentence structure.

Shame good Grammer is not taught...

Ok so there was a few typos. Big deal I'll fix them but I thought that was pretty straight forward...why cause it was long winded?.I'll just dumb it down for everybody. Why no check engine light work lol bulb look good no get tcm flashout for codes. Btw maybe you should have been taught good grammar because it's grammar not grammer there's a difference look it up. Instead of just being a **** to everyone coming to a forum looking for help right away. I had to rush the post during like the only 10 minutes i had outside of work and not being bothered by family

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[IdiTrev]

Tested my vss that was in the truck last night and it ohmed like 1700 and change. That was through the diagnostic port in the engine bay. I read on a post that they're supposed to be between 1200 and 1500?. So last time I went through this crap I saved my sensors that I changed because i suspected some weren't bad and glad I did. When I got off work today I tested it right at the sensor, unplugged on the diff and it tested at like 1800 and change. also I had ordered a brand new ngk brand vss that got here today and when I tested it it tested at like 1900! So a bad one? I pull out my old one I swapped out a couple years ago that I think was duralast and it tested in at 1400 and change. The only acceptable one and it's duralast of course. So swapped that in and reconnected the batteries and still limp mode. still no speedo. Still havnt figured out anything else on the check engine light yet

 

[Black dawg]

Speedo is mechanical......does this truck not have the speed sensor in line with the speedo cable where in goes into the transmission?

 

[IdiTrev]

Yeah I don't get why the speedo wasnt working maybe it was just stuck or sumthing but I pulled it out and put a socket with a paper towel on the plastic gear and spun the socket with a drill while filming the gauge cluster with my phone while I was under there. It did spin the needle so idk what the issue was. I just put it back together trying to figure out why my Check engine light won't work now

 

[Black dawg]

The drive gear is probably worn out

 

[franklin2]

I am wondering if you even have power to the computer? Is there a blown fuse somewhere? I think the check engine light should light up each time you turn the key as a check. It seems your whole TCM system is dead.

 

[Cant Write]

@IdiTrev when you say “limp mode” is your trans stuck in 2nd gear? Or it shifts at full line pressure?

I blew a 15 amp fuse the second before i left the driveway on a 2000 mile road trip last summer. Killed my speedometer, odometer, cruise control, and my OD was flashing. It shifted at full line pressure.

Stopped for supper 60 miles in (I was driving through the night) and while the kids ate, dad and I found the blown fuse (15 amp) replaced and all was well.

The government had tied into that fuse and I shorted the wire when I cut it.

Mine is a ‘92, and I’m sure the differences are many. Hope it helps.

And as a side note, I’m not trying to start a fight, but your first post read like verbal vomit. And I know I can’t write correctly (username).

 

[Noiseydiesel]

At what point in time did you pull out the DVOM and start checking voltages and grounds?
I had a few gremlins in my truck that went away when I pulled apart all the grounds, scraped them clean to bare metal, wiped with grease, remounted and another coat of grease.

Your trying to swap out components to eliminate potential basic electrical problems. As long as your playing with that eff4OD, have you also replaced the Range selector switch with a known good unit?

 

[IdiTrev]

I would think its full line pressure and naybe starting in 2nd it doesnt seem
to want to move as easy and when it shifts its so hard it worries me. Overdive light flashing is what I mean by limp mode. At least that what I thought it meant. Well i had put a new mlps on it before this started last year and it barely moved amd got miles on it but i have a new rostra one here on stand by to try now as well as a new ntk FIPL i got from rock auto because none of these things seems to last worth a crap anways. i started thinking okay maybe these duralast crap sensors just wont last if the trucks parked for a while. So i started switching all sensors to factory or if i couldnt find factory a better quaility part at least by not going duralast. I'm thinking my problem lies in the wiring between the CEL and teca and im gona pull the gauge cluster and maybe try and get a spare for diagnosis purposes orbitals had read that someone said you can clean the printed circuit board contacts on the back of the cluster with a pencil eraser and i may try that for the CEL. I havnt specifically been able to find the wiring diagram for cab and gauge cluster and sti for 87-91. only the 92 n up. Today I confirmed I do have power at the teca relay where its supposed to be constant and on and off with key in the respective spots but still need to find the right spots for checking pins at the teca connector for continuity and try and make sure power is indeed getting to the teca and coming out. I don't know if i know where all the factory grounds are but I tryed to clean all I could find. Last year I had replaced all the main battery to engine grounds with new wire )the positives and to starter and and signal too but unrelated) the one ground that goes to the wipers and just cleaned any others I could find like the one at the fuse box under dash. I do suspect that my ground to the teca may be a culprit tho because at one point a few years back I had a rat do some damage to the wiring and had to fix some things one of the things it chewed up was the teca ground but I had cut it back and spliced a new ground into it and it was working fine for months after that. I checked it and the connection was still tight and I cleaned the ring terminal on the end but I do plan to repin some of the teca plug though. ground definately included which kinda brings me to my next question. I don't know the exact name but the like barrel and pin terminals for the connectors...which ones do you guys use. I got tired of buying the crap lil dorman multipacks at the store with like 2 of each style plug terminal. I had ordered some and they ended up being just barely shorter like a 16th of an in making me worry about having good contact but they seem like they should hopefully work just a lil less contact area just wondering which ones you guys use to re pin these plugs. I accidentally ordered size 14 to 18 though instead of 10-12 like I needed for the teca ground though lol but the others are ok for everything else it seems so waiting on that. But I mean ive had the mutimeter out when I swapped all these sensors out to check ohm ranges and voltage sweep and all that for vss and fipl and like I mentioned the teca relay. Vss seemed good fipl seemed good. Havnt done the test procedure for the mlps in there yet but i was kinds thinking the plug might be able to benefits from a re pinning on that too as some of what I can see going into the plug does looks corroded still after using contact cleaner multiple times. I'll try and get another update soon hopefully these terminals I have are good enough to repin the mlps plug.

 

[94turbocrewcab-lb]

I recall changing a sensor up front on the engine when I lost my speedo..can’t recall what it was. Cam gear sensor maybe? It was a black top with large flats for a wrench. Two wires coming out of the back.