I picked up a 91 25 4X4 for $500.00 ran but knocked like a **** pulled the pan, 5 rods look brand new & #6 is BLACK & the crank is obviously eaten. Yanked it & picked up a complete 150k engine for 800 bucks! Got the whole thing together, runs good, drives ok but no spedo & wont shift into OD! The spedo in the truck says 77K & I KNOW thats not right! put new sensor on the tail of the tranny (mounts on driverside rear) still nothing. Speedo doesn't work, no overdrive. (also no wait to start light, how does that come into play?) I've read through 50 pages on here and realize this is not the first post regarding this. My question is rather than continue to throw sensors at it to make sure I'm on the right track. The overdrive switch/button on the dash works, it illuminates if you push it on/off is that normal? I have pulled the sensor on the top of the transfer case to replace next (transmission shop told me that on the 4X4 that thats the one that does the spedo. true?) Also the sensor from the top of the T-case has a little spring on it, when I go to put it back in is there any thing special I need to do or worry about? I cant see up there so it's all by feel, hate to drop that spring in & have to pull the whole fkn thing to fix/find it.

I know allot of info, but after reading as much as I have and not finding it I figured Id ask everything at once.

 

you have the VSS plugged into the rear, but there is an L shaped gear reducer box that goes on it too... that will fix the speedo error.

there's a thread here that details this, guess more searching? has to do with checking proper power to the PCM.

 

Yea, replaced that whole thing, (I think?) just like a speedo drive w square shaft that plugs in and had a cap that screws on to hold it in place. Then just has a plug (2 wires) that plugs onto it correct? still nothing! pulled the sensor on top of the transfer case and checked it, it's bad! jumped the wires and 4wd indicator on dash comes on. Does this somehow route through it/tie into speedo? doesn't seem like it would matter. 4wd indicator just seems like it is just that an indicator. I'm just kinda stumped! Tranny shop told me that the T-case indicator is the speed sensor, from what I read it is and it isn't. I know for a fact the sensor for that is bad but is it the "fix" or what? I've spent hours reading and at the parts store (who can't even find the T-case sensor/indicator), calling the dealer (who says that there are 2 different ones bit doesn't know) etc. It can't really be this hard. As far as the PCM goes, I read somewhere in 50 or so pages that the truck won't charge if the PCM is bad? I don't have that issue so what the heck am I missing?

 

Did some more looking, by "L shaped" do you mean a reducer of some sorts? I found a pic on a thread that had one, looked like it went inbetween the tranny housing and the sensor. Here is what mine looks like, it's the new one but the new is the same as the old, just screws right to the tranny. This is how I got it, which doesn't mean that someone else hasn't changed or removed something!

 

Its suppose to have a ratio adapter. I think it speeds up the vss to make it read correct.

 

slows it down. there is another L shaped box that goes inbetween.

 

So guys I'm getting all kinds of info, some say it has one, some say it that it doesn't have one and that the sensor goes directly on the tranny. At the dealer again today (diff dealer) looked it up but couldn't tell me by vin if it has it or not and even if it needs one it's no longer avail! None of the "techs" (part replacer's) know and the computer (according to them) doesn't go that far back with updates/bullitins etc. they don't even list a part number for the ****** thing!

So I guess if I do need it and it's not avail is there another source for one? Parts shop cant find anything. If it doesn't need it what next? Getting really frustrated! spent more time chasing this than anything else on any car or bike I have ever delt with.

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Update. day 2............LOL yea ratio adapter was missing AND the drive that comes out of the tranny was rounded so when shaft from VSS goes in it doesn't turn it. Drill trick worked to check to see if speedo was working. Pulled output gear drive and sure enough it's the culpurate (minus the missing parts) I'm betting the ratio adapter went bad somewhere along the line & they just removed it & plugged VSS right into to output. (weird that Dodge would use same fitting on both allowing this to even be an option) that probably worked for awhile. before it rounded the hole out. So now speedo works but is pretty inaccurate and still no OD. "wait to start light" doesn't come on so now I'm thinking the coolant temp sensor? Also the ratio adapter must actually speed/increase the reading as now when I'm doin like 40 it reads about 20 or so.