I’ve been having a little trouble with my automatic transmission recently and need some opinions. By the way, this is a ’93 D250. When the transmission is cold everything works fine until it goes into overdrive. Once it goes into overdrive it will only stay in o.d. for a few seconds then drops out. I let off the accelerator and it will shift back into o.d. and then drop back out. Once it warms up, no problem. I asked my transmission man about it and he said that it sounded like the seals inside the transmission were getting old and not letting the pressure stay up. Once it heated up, the seals were “sealing” and it was working. When he told me it would be about $1500 to rebuild I decided to do some checking. I talked to the guy who I bought the truck from and he showed me a component that is mounted to the top of the fuel pump that is about 1.5” x 1.5” square and has an electrical connector going to it with (I think) 3 wires. He said that he had o.d. trouble with a ’92 that he had once and that component fixed it. Does anyone know what that component is? And does anyone have any other opinions about what could be the problem? (Fluid level is good)

 

HLC,<br>Happy new year, welcome to the board. Sorry to hear about your problem to start off the new year. I have a 92 W250, same deal as yours pretty much, and had/still have the same problem as you. The item on top of and in front of the injector pump is your throttle position sensor(TPS). I had my O/D act up and this is where I traced the problem to with the help of a bunch of people on this website. The TPS senses your throttle position by means of measuring electrical voltage. The higher the voltage, the higher the throttle setting. If this thing is out of wack, it will send your computer bizzare information. In my case, I had a wiring problem and the voltage was too high, so the computer shuts the O/D down if the voltage is too high. Wiggling the wires fixes my problem for a few miles. I took it to a ******* in Salmon Arm (I was on my way to alberta when it first acted up) and they assumed I was dumb. I'll admit I'm not smart, but still know one or two things about my truck. They told me that I would most likely need a new torque converter and a few other unrelated gadgets. They turned red when I told 'em what I know about these things I took it to a good family friend in the tranny business, and he quickly told me it was electrical. He then shipped 'er off to a buddy of his who scratched his head, tried a few things, charged me $1100 and gave it back with still no O/D. I did some of my own research and found the problem in the plug at the TPS. One thing you can do is check error codes in your computer. To do this, shut off your truck, and turn the key from OFF to RUN 3 times each without starting the engine. The check engine light will be on for a few seconds, then go out, then start flashing a sequence of codes. It will flash a few times, pause, flash some more, then pause a bit longer. This is one code. You'll most likely get 1-2 on the first one. This is normal I beleive. What comes after that is what you're interested in. The last code you should get is 5-5 which means end of codes. As far as the tranny guy telling you that you need new seals goes, I'm of the oppinion that as the fluid warms up it gets thinner and therefore it would be more likely to leak off pressure. One other thing it could be is your tranny temperature sensor on it's way south. Keep us updated.<br>Sorry about the long answer and hope it helps you some.<br>Happy New year.

 

I've had od problems with my 93 twice, both times the problem was with an electrical connection.<br>The 1st time I had to replace the connector to temp sensor located in the tranny line on the drivers side, this took some time to track down. A year later my speedo started acting up, which also caused it to jump in and out of od. I repaced the connector to the speedo sensor...fixed again.<br>I also spray switch cleaner in the tps every once in a while.<br>I'd check all your connections, spray the tps with switch cleaner to see if that fixes your problem first...tps's aren't cheap.<br> <br>

 

my 95 had the same problem I told the tranny guys about the problem B4 they rebuilt it then after it still did it so they said it was the torque conv. so they ripped it out put in a new one and it still did it so they ripped it out again and put in another one STILL DID IT ripped it out again and put in a new valve body still did it then they gave up and ripped it out again and put a whole new rebuild in it and it STILL DID IT. This was done all under their warranty. They gave up went to the ******* and they dignosed it as the tranny temp sensor in the cooling line. $22 part + labour. The sensor will down shift into 3rd gear if you are pulling too heavy a load in OD because the tranny oil temp is to high. mine was defective.<br> The throttle position sensor is anoter thing that I allways battle with and the fellow B4 me was right to spray electrical contact cleaner into the tps.<br> You will know it is this problem because it seems to happen at the same rpm everytime if you are cruising at a constant speed.<br>

 

Thanks guys,<br>I haven't had a chance to try anything yet but it sounds like I have a sensor problem and not a tranny problem...Thank God. You guys have saved me at least $1500. <br><br>Yomitch....what you described is exactly what mine is doing. <br><br>Thanks again...Joe

 

One more question, Are these sensors (TPS and TTS) just bolt on components? The TPS looks easy enough to change but is there anything underneath it to surprise me? Do I need any special tools etc etc....

And one other thing, if I do end up needing to replace one of these components, are these Cummins parts or do I have to get them from Dodge.

 

I would think that anything to do with the Dodge Computer and transmission are gonna be DC parts. Or you could go aftermarket, sometimes they are a little better for a replacement part. Anything under the TPS is fair game at the local Cummins store..<br><br>J-eh

 

I got my TPS through NAPA

 

Ahhhhh, the dreaded TPS strikes again..... geezzz I wish I had a buck for every time I see a thread like this one.... I swear DC did this on purpose..<br>The TPS can get dirty internally or just wear out. It can have a bad elect. connection(s). You could have a temp sensor giving you grief if it was happening at high temps. (the high temps sensor kicks in at approx. 270*F and locks out the OD till temps drop.)<br><br>The TPS itself will often &quot;wake up&quot; if you &quot;adjust it back and forth a few times. You need to read the following first. Once you've gone thru it, you'll realize that you need to just work it back and forth slightly a few times before the final setting. Too much twisting and it'll go Fubar on ya, and they ain't cheap!<br>BTW **NOTE** take initial dc volt reading before touching the thing, that way you'll have a baseline (original) reading.<br><br>&gt;&gt;TPS ADJUSTMENT....<br><br>The TPS has a 3 wire connector on the top, engine side.<br>The center wire is orange I believe. <br>Under the TPS body, is a shaft that protrudes downward. The shaft has a hex head end that fits into a 'female' hex socket.<br>This shaft is lightly spring loaded. <br>Right near the top of the shaft were it first comes out of the TPS body, are two &quot;flats&quot; were you put your open end wrench to adjust.<br><br>You'll need a DC Voltmeter, as safety pin, or paperclip with the end slightly sharpened, and a combo wrench. I think its a 7/16&quot; or 1/2&quot;.<br>Slip the safety pin or paperclip into the 'socket' part were the center wire comes out of until it makes connection with the metal jacket inside. <br>Connect the &quot;+&quot; probe of your DCVM to this.<br>Connect the &quot;-&quot; probe of your voltmeter to the &quot;-&quot; terminal on the battery (it's just convenient)<br>Turn on the Ign. key (do not start truck) and check the &quot;at rest voltage&quot;.<br>It should range between .7 VDC and 1.25 VDC. (make a note of the reading for reference.)<br>Next, slowly cycle the throttle smoothly to WOT and watch the meter.<br>It should increase smoothly with no jumps or spasms/twitching.<br>If it does, the TPS is still working ok, if not you've got a dirty one or its failing.<br>I believe the total increase (above &quot;at rest voltage&quot should be about 2.75 VDC. <br>Now, you need to go back to that shaft coming out from under the TPS. <br>Use the wrench to adjust the voltage SLIGHTLY!<br>Start with .2 VDC to begin with.<br>Increasing voltage will cause the 3-4 shift to happen LATER. <br>Decreasing voltage causes the shift to happen sooner.<br>I found that there was a point were the shift happened later, but also tended to cause the downshift (4-3) to be a bit touchy too, so you need to adjust a BIT and drive each time.<br>When you do your test drive try to use the same throttle pressure/RPM for each, that way you'll know what effect you had with the adjustment. I did a &quot;medium&quot; throttle (1600 RPM) and a WOT test each time.<br>Before I had the tranny work done mine ran just fine at about .7 VDC - .8 VDC &quot;at rest&quot;.<br>Last thing to ckeck... make sure that your TV cable returns properly. The lever on the trans. case should move all the way forward with the truck off/idle. I had to add a &quot;universal&quot; throttle spring to be sure that happened, otherwise the line pressure(s) at idle are already increased above what they are supposed to be at idle.<br><br>I hope this helps, one last thing, make sure you hang your tonque out the right side of your mouth, and squint with the left eye... &lt;&lt;<br><br>I explained this so many times I finally typed it into a text file for cut N paste now..<br><br>Bob.

 

Thanks Bushy,<br>Sorry it has taken me so long to come back to check this thread. I never had time to get back on this problem to try to fix myself. I had another prob come up and just had to take it to the dealer and they fixed both of my problems. The service manager said that I was sitting at .51 vdc and it should be at 1vdc give or take. I just drove it home a few minutes ago and I do believe I may need to do a little tweaking. Looks like I may need to come down a little....it's taking a little too long to get into O.D. But Thanks again for all the good info....Joe

 

Hey Joe, you seem to be chasing that same **** gremlin too . My tranny shop said it was the cable on the tranny that was causing it, YEH RIGHT. But my TPS is reading correct, I didn't think to ask about the trans temp sensor....DUH. Thanks for the post, but it'll have to wait until after Saturday, 10 degrees here is COLD for us.

 

Guys, honest to gosh, I don't give a rodents' rotund rump what the book says, there is no &quot;right&quot; setting for the TPS. It almost always has a personality different from the next one..
The throttle valve cable is different, it does have a setting required for proper shifting and tranny life. In fact it's very important that the throttle valve cable be set correctly or you WILL be paying big bucks for an overhaul...

I have found TPS settings ranging from as low as .45 vdc to as high as 1.20 vdc depending on the truck/tranny/throttle valve cable.... assuming a stock tranny..
If your original setting is showing as, say, 1.00 vdc, then go down to about .85 vdc and test drive it.. otherwise..
Start your testing at about .5vdc, and go up in .1 or .15vdc increments... you'll find the setting that works best for YOU.
Also, when you make an adjustment with your voltmeter, cycle the throttle open/closed 3-4 times and re-check the setting, you may find it has crept a bit, either up or down. Double check it, test drive, go from there. I like the medium throttle position, say 15-1600 RPM to check it. That is about right for normal 'pull away from stoplight' RPM's.
Last, don't be too quick to chuck yours out and buy a new one..... they are NOT cheap!!
The temp sensor will not allow OD to work under 90*F (I think) and will lock out OD when you are around 270*F. That kind of temp will kill a tranny quick due to oil breakdown.