Hello, I have the exact problem with my transmission that is described in the following post. I realize the truck in the post is a diesel but was hoping someone here could tell me if the solution for mine could be the same.
I have a 1996 3500 Ram Van with a V8.
Does it mainly do it when climbing a grade or just driving normally?
The torque converter is designed to lock-up in OD (4th) and in 3rd when the OD switch is off. If it's constantly searching when you're driving normally, I would suspect the TPS since the PCM uses it's input signal for the transmission. Your transmission is electronic (46RE).
jbirdmotox
08-22-2007, 11:17 AM
It does it when driving normally with the OD switch on or off. If you are going along about 35-45 it can't decide which gear to be in. It just keeps shifting up and down. If you speed up over 50 it will shift up and be fine. I you slow down under 30 it will shift down and be fine. I will also say it shifts very smooth from a dead stop all the way to overdrive as long as you keep accelerating.
Thanks, Jon
stev
08-22-2007, 06:33 PM
I would look at the TPS along with knowing what ATF fluid was used in that tranny. The correct fluids of either ATF+3 or ATF+4 should only be used.
jbirdmotox
08-23-2007, 08:02 AM
I guess I will have to check into the TPS. I flushed the entire trans, changed the filter, and put in ATF +4 last fall. I only drive the van to pull my camper so it doesn't get driven too often. I'm taking a camping trip to western NY in a month so I figure I need to get off my butt and get it fixed...
Jon
stev
08-23-2007, 12:34 PM
ha-ha, all too funny. I live up here in WNY near Niagara Falls. So, you're camping in my neck of the woods (or water falls).
The TPS is as defined a Throttle Postion Sensor. In all of it's function, the TSP is really a pot feedback to the PCM. When you press the gas pedal, it moves the cable that moves the TB valves. When the valves move, the TPS connected at the other end picks up the postional movement.
I once took my TPS off this spring, turn the interface back and forth easily, heard a little pop inside and it worked fine again. Something inside got worninto a preset range, thus the TPS wasn't working it's full travel. I then went ahead and clean the electrical connections too with the CRC QD electronic automotive cleaner. Since you're going to have to take the dog-house off, you might as well clean the IAC too. See the sticky in this Ram Van forum or the Ram Van "How To" section.
PS, for those reading this thread we need more How To's in the How To section, so get busy. :) :) :)
jbirdmotox
08-23-2007, 03:33 PM
Yep, the IAC was on my list as well since I have the surging idle problem. I will check out the movement of the TPS like you did and give it a try. I'm not sure how much a new TPS costs but I'm sure it's more than I want to spend if I'm not pretty darn sure that's the problem.
alloro
08-25-2007, 02:49 AM
Did you try disconnecting the battery cable for a while? The PCM stores your driving habits and if you were pulling a trailer shortly after the last time the battery was disconnected, then those towing shift points could be stored and causing the erratic shift patterns. Removing the power allows the memory to wipe and your driving pattern to be relearned.
jbirdmotox
08-28-2007, 08:56 AM
Well, I messed around with the TPS last night. All the connections look fine and the internal movement seems smooth as well. I also ran a ground wire from the TPS directly to the battery. Basically none of this had any affect.
This leads me to my next question: What should happen if I disconnect the TPS? I assume if it's bad nothing will happen. The trans will behave the same as it does now. I also assume if it's good I will notice a difference in the way the trans acts after I unplug it?
Just grasping at straws now. I may have to take it into a shop....
Thanks, Jon
Dodgevanman
08-28-2007, 12:00 PM
If you unplug the TPS lots will happen. Number one, you'll throw a code that can only be cleared by a scanner since it's OBDII, and two the engine won't run properly because the PCM won't know how far the throttle is opening to deliver the proper amount of fuel.
Don't ya love technology?
jbirdmotox
08-28-2007, 01:18 PM
That figures. I just checked the auto parts store and it's $51 for a replacement. Of course there are no returns on electrical parts.
I've never been much of a gambler so it's off to the trans shop. That is unless there are any more suggestions....
alloro
08-28-2007, 06:19 PM
You can test the TPS with an ohmmeter to see if it's good or bad rather than buying one on a hunch.
jbirdmotox
08-28-2007, 07:24 PM
Any idea what the TPS should read? I've searched here and I also have a subscription to www.alldata.com but haven't found much about testing one.
As a side note has anyone bought any parts from this site?
www.autopartauctions.com
They seem to be selling a TPS for $11 plus shipping.
alloro
08-28-2007, 08:39 PM
Use the ohmmeter across the two outside pins to get the total resistance of the TPS. The middle pin goes to a "wiper" type of contact that moves from one outside pin to the other as the throttle is opened more and more. To test it, connect the meter from the middle pin to one of the outside pins and note the reading. If it's zero (or close to) the resistance will go up as you turn the center of the TPS until you reach the maximum resistance that you got from reading the two outside pins. Now move the meter lead from the outside pin to the other outside pin and do the same test. This other pin will have the opposite resistance effect of being connected to the first outside pin (as one goes up, the other goes down.)
If the TPS works as I've described then the next thing to watch for is any jumps in the meter reading as you turn the TPS up and down. An analog meter is better at seeing this than a digital one because digital meters have a slight delay built into their displays. Any jumps in the reading indicates a loss of contact by the center "wiper" contact.
If the TPS does not operate as described or if there are jumps in any of the readings, the TPS will need to be replaced.
jbirdmotox
08-29-2007, 08:49 AM
OK, thanks a lot for that info. I will be checking it out tonight.
Jon
jbirdmotox
08-29-2007, 05:54 PM
It looks like the TPS is the problem. Using the procedure posed by alloro I found that I get the same Ohm reading across all the pins. Basically the two outside pins read the same as the two left pins and the two right pins. Turning the TPS "wiper" has no affect on the Ohm readings.
Jon
alloro
08-29-2007, 08:44 PM
Are you sure your meter leads were making good contact with the pins. I ask because it's weird that the center to either outside pin would have the same reading as the two outside pins. Usually when a TPS goes bad there is intermittent or infinite ohms from the center to either outside pin.
I've attached a schematic of a TPS that might help with understanding how one works. N5 & K8 are the outside pins while K7 is the center pin. Basically N5 to K8 is a fixed resistance. K7 to N5 or K8 is a variable resistance. So in looking at how a TPS works internally, you can see how having the same reading between any two pins is a highly unlikely occurrence.
jbirdmotox
08-29-2007, 09:23 PM
I'm positive I had good contact. I had the TPS clamped in the vice on my workbench. I must have checked it 15 times because I thought I must be crazy or doing it wrong. I even had someone turn the TPS while I had the leads on the pins. Nothing would make it do anything different. It had the "total resistance" value all the time.
Thanks for the schematic. I was curious what the thing looked like on the inside so I cut it open. I could see how it was suposed to work but for whatever reason insn't.
I'm going to pick up a new one tomorrow and bench test it first.
