Ok Gang...I've got a for sure way to diagnose torque converter lock up issues where it lock and unlocks at about 45-50 MPH. I had a gent call me yesterday with this problem and he's replace both batteries, alternator and the APPS sensor. Attempted all the different wiring issues (adding ground, tinfoil etc.) nothing worked. Like I told him the truck ran 11 years without all this stuff and doesn't require any wiring change to make it work. What it needs is the damaged part to be replaced. So he's returned the wiring back to stock setup.Now I told him to unhook the alternator fuse and take it for a ride... Guess what... No problems! Even though he replaced the alternator it has a damaged diode in it and it bleeding AC noise into the electrical system.So before doing any wiring mods, tinfoil, adding grounds, adding filter... PLEASE! Bench test your alternator! This is the second time I've suggested this and both time resolved the torque converter lock up issue.

Mark,Have you tried pulling the 140 amp alternator fuse? That will tell whether or not your alternator is the faulty part if that stops it. If it keeps going, check your batteries. Take them to Napa or similar store to have the alternator bench tested and also the batteries if the alternator turns out to be good.I had the same issue exactly, pulled the fuse and it went away. Replaced the alternator and it was fixed for a bit, the new one went away after a month, it has been replaced under warranty.In ready Moparman's study of this issue, I agree with him about an alternator causing a lot of problems as it is connected to just about everything in your truck. A faulty alternator with a bad diode could be suspect in alot of other equipment failures not to mention a VP 44 or others. You might read Mike's information, think on page 1 of this thread.Good luck. I too am new to this forum and have learned so much, these guys do know what they are talking about and they don't give you a bad time for not knowing much. They are a tremendous help.

Mark, Have you tried pulling the 140 amp alternator fuse? That will tell whether or not your alternator is the faulty part if that stops it. If it keeps going, check your batteries. Take them to Napa or similar store to have the alternator bench tested and also the batteries if the alternator turns out to be good. I had the same issue exactly, pulled the fuse and it went away. Replaced the alternator and it was fixed for a bit, the new one went away after a month, it has been replaced under warranty. In ready Moparman's study of this issue, I agree with him about an alternator causing a lot of problems as it is connected to just about everything in your truck. A faulty alternator with a bad diode could be suspect in alot of other equipment failures not to mention a VP 44 or others. You might read Mike's information, think on page 1 of this thread. Good luck. I too am new to this forum and have learned so much, these guys do know what they are talking about and they don't give you a bad time for not knowing much. They are a tremendous help.

I did read the part on bad diodes in the alternator causing a/c voltage leaks into the system but I have read stories (on CF) of people replacing the alternator more than once with still the same problem, I like to look for fixes that no else has tried because we have not found the magic bullet yet. Right now I suspect that even though the alternator field circuit (from the ecu) is not tied into the A/c generator circuit, the generator's a/c electrical field could be inducing voltage or RF noise into the field circuit. Over time the ecu becomes more likely to be affected by interference due to heat cycling and ground connection degradation. If I completely disconnect the interference from the ecu it may stop affecting it. Or at least that is my theory. I would like to say mopar1973man is pretty cool for giving out all the advise that he does:thumbup2: and the people here seem to be pretty smart, I am a technician and this is the type of problem that causes me to loose sleep. I think we are close to the solution and if I find it I plan on sharing it as much as possible.

I tightened/ cleaned all my battery terminals. The grounds were so loose I could turn them with 2 fingers. I installed battery post shims and that works great. I also checked the AC volts at the battery; 30 VAC and just under 14 VDC. I don't remember if I checked it before I tightened the posts, though. I will check it again with the terminals tightened just to see what it is at.I also cleaned the grounds going to the body on each battery and the ECM ground.So far this has fixed the TC lock/ unlock issue for me.

Well Guys, I am another one who is having this issue. Just bought the truck a couple of months ago and really love it. The only thing I have done so far is pull the neg battery cables off and cleaned them a bit. It did work for a few weeks but has come back.It does not do the lock unlock issue all the time. So my question is if I pull the fuse for the alt, how long can that be left out? I am not a motorhead or a whiz at mechanics. I can do a little bit, but this might give me more grey hairs :banghead: I also just got to thinking.........Love the truck.......but I am wondering if I need my head examined :cookoo:Thanks!Rob

Not extremely long 10-15 minutes driving at most, turn off everything electrical try not to use the brakes (brakelights) I once drove a car with no alternator belt for a half an hour (emergency situation) I had to recharge the battery to get it start once I put a belt on it. But I would not recommend driving for that long.

Not extremely long 10-15 minutes driving at most, turn off everything electrical try not to use the brakes (brakelights) I once drove a car with no alternator belt for a half an hour (emergency situation) I had to recharge the battery to get it start once I put a belt on it. But I would not recommend driving for that long.

Hmmm, that will make it tough since its an intermitten problem for now. Thank you for your reply. Rob

Just tryed the 140 amp fuse test myself and the second the torque converter locked the computer threw the check gauges light and the voltage dropped like a rock so I pulled over real quick, After I hooked it back up the voltage was ok the batteries had not drained Going to try again later and ignore the stupid light and gauge.

My truck never threw a code or anythin when I had mine out. I know its not a fix but I put a lock-up switch in mine and as long as you dont forget to un-lock before you slow down below mph or so you will be fine. http://www.tstproducts.com/Torque%20Converter%20Lockup%20Switch.pdf

Do all the terminals; not only the negative ones. Also, clean the grounds that go to the body from the negative cables.While you are at it, do the ECM ground on the firewall, passenger side.

I was reading on Cummins forum and someone had added a ground from the pcm(passenger side of the firewall) to the negative terminal on the battery. I added this wire to mine about a week ago and have not had the TC issue once since installing the wire. Just to be sure I unhooked the write before leaving work today and the TC issue was back within a few miles. I pulled over and reconnected it and had no more problems the rest of my drive. Might be something to consider trying. Sent from my DROID BIONIC using Tapatalk 2

I don't know too much about electrical. Couldn't a guy take a portable radio, while the trucks idling and point the antenna at different areas under the hood to find the source of the RF noise ? I don't really know but wherever the loudest static comes from would be a clue?This is quite possibly the worst suggestion on the forum ever:cookoo:

Hey guys,Was thinking of pulling my alternator fuse for the drive home after work today..2 questions, where is the fuse? Is it obvious to find? IE - diagram on the underside of the fuse lid like most vehicles?Second, my drive home is about 30 minutes.. am I risking any damage having the fuse out for that long? If someone could give me an answer in the next ~20 minutes, that'd be great!

Try 2 thing...

[*]Disconnect the alternator fuse and go for a ride.

[*]Bench test the alternator have it test for diode pattern.

If disconnecting the alternator fixes the problem you know the alternator is the causes. Or you could have it bench tested and check for AC pattern being output from the alternator.

As for the P0500 code...

http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes/190-p0500-no-vehicle-speed-sensor-signal

OK! Problem solved! Yippee!!!

Took the recently purchased Alternator back to O'Reilly's where I got it from, had them test it on their tester. They told me they run the test 3 times and if they get a PASS all three times, its a good alternator. When I asked about measuring AC Voltage, they looked dumbfounded, so I asked them if I could hook my multi-meter up to the alternator while they tested? They agreed! So now this alternator is reading .35 Volts AC as the first test PASS'S, they run the second test and we get a FAIL, the guy gives me a funny look, checks his wires and runs the third test and we get another FAIL. So the guy now rells me guess we have a bad alternator but they don't have another one on the shelf and I will need to wait till tomorrow to bring one in from the other store. I say, I'm OK with that, but that I've learned my lesson and we are going to have to test the next alternator as well before I leave the store with it. The next morning (yesterday) they call me and let me know the alternator is in and I can come down and pick it up. We do the test like before, and this time we get a PASS, PASS, PASS, however my multi-meter is reading 0.3 Volts AC, and then I also notice that on their machine there is a box at the top that says Diodes and across from that box on the screen says N/A. So I ask the guy about it and he says their machine has no way of testing the diodes, it only test for overall condition of the alternator. Unhappy with what I'm hearing and looking at, I request my money back which they had no problem with at all, however the core I earlier took in was no longer in the store so the gave me cash in the amount of $215.00 (their core charge on that alternator $36.00 along with the full purchace price of $179.00.)

By this time I have no core, only to find out all the other auto parts stores around town are charging a $70 - $80 core charge for this alterrnator, and a lot of the places have no tester. Starting to get a bit frustrated, I decided to quit messing around and go to the most reliable place in town I know of, a small family owned auto electric and mechanical shop (Auto Electric, Anchorage, Alaska). I was hoping that maybe they had heard of this isuue I am having with the TCL and get fixed up with a good alternator. They rebuild all kinds of auto electrical parts right there in house as well a run a full service auto mechanic shop. Well,,,,I explained my problem to them and showed them a printed copy of the troubleshooting procedure I got from the Mopa1973Man website, to which they said...never heard of this before. However these guys are real pro's and they didn't blow me off. They took my concerns seriously, brought two techs in out of the shop to talk with me about this, as I explainded to them the 0.1 Volt AC upper limit thing. They genuinly got concerned and were pulling down alternators, checking them on the bench and checking outputs at vehicles in the shop. In all, I was in there for about two hours while they tested and discussed and in the end the shop found me a NEW alternator and gave me a heck of a deal @ $239.00 w/no core charge. The NEW alternator was putting out 0.22 Volts AC on their alternator bench vise, and that concerned me cause I was looking for something under 0.1 VAC. However in further discussion, the techs I was working with concluded, (and BTW they turned out to be right), that the test machine itself was putting off AC Noise and that the Fluke Meter was picking up that AC Noise during the test, and that since the Voltage Regulator is on either the PCM or ECM, the only way to accuratly read out the AC output on this alternator was to put it on the vehicle and measure it at that time. So,,,I took the alternator home, hooked it all up, and WALLA... measured at the battries -0.01 Volts AC @idle, and 0.00 Volts AC @2000 RPM. Feeling pretty good at this point I take it for a test drive. Runs and shifts perfectly. NO MORE PROBLEMS!!!

Cory, I believe he's the manger or maybe owner, at Auto Electric said though he's heard and dealt with a lot of Dodge Cummins issues like this before, had never heard of this shifting problem being linked to + 0.10 VAC output on the alternator. He asked me to check back in with him to let him know how all this worked out. I will do that on Monday, as well as express my thanks for all the personal attention, efforts and concerns Auto Electric gave to me to adress my problem.

In the meantime, my utmost gratitude to Mopar1973Man for sharing your knoweledge and wisdom on this issue. I had tried all the bandaid tricks only to have them each work for anywhere to a couple hours to a couple days or so and then reappear. I believe what was happening was that as I fixed a ground or foiled a wire, it masked the problem just long enough for the diodes on the alternator to get a little worse and then BOOM, the problem is back!

Very good information Mopar1973Man!!!

Happy Holidays!!!

Good job!!

Craneop that's an awesome story and update thanks for sharing

Hi Guys,Tons of good info in this thread (site too!). I know I'm new but I want to add a little info I didn't see that might help. If its already mentioned, please disregard. I'm seeing there is a little confusion between voltage regulators and rectifiers. The voltage regulator in the ECU is what controls the amount of DC voltage from the Alternator (simplified explanation). The rectifier in the alternator is what takes the AC the alternator makes, and converts it to DC for the vehicle to use. This is the part with the diodes that go bad. They are two different animals. Using an external Voltage Regulator wont solve the issue, as its not the cause of the issue.I think the only way to solve the AC/RF noise issue is to rebuild the rectifier with higher quality components. I don't have the cash to get a new alternator and tear it apart to research more, but I'm pretty confident that if higher quality components are used we'd have great results.Thanks,Travis

Just wanted to update I checked for ac voltage at the batteries and at the 140 amp fuse, the highest it showed was .026, one thing I have found is when the engine is off the throttle position reading on my scanner is steady when the engine is running it jumps up and down slightly, it showed the same result with the serpentine belt on and off.

So after giving my input I decided to go check my new-to-me 99 to see if there were any RF issues. I haven't had any TC issues, but I wanted to check anyway as I've only had the truck a week.I'm not sure if I'm glad I checked, or sad. 120v AC. OUCH! The PO had changed the alternator and foiled up everything in sight. I'm going to add another ground to the alternator because I think its a good idea anyway. Does anyone have a bad (AC issue only) alternator they would be willing to send to me? I want to take one apart and look at the rectifier to see if I can build a better one. I will do a writeup and post it here. I will send you back the fixed alternator once I am done testing.Travis

hello all,I stubbled across this TC lock/unlock forum while looking for the answer to this problem, I have read all the patch fixes, etc. and this fix seemed like the most promising. I have a 2002 Ram 2500 Cummins, auto trans, about 120,000 miles. I cleaned all the terminals then removed the 140 amp Alternator fuse, the TC issue seems to go away as described with the alternator out of the equation. Then I removed the factory alternator and had it tested, on their machine everything passes, I then asked for the details of the test and noticed the AC Ripple Voltage was 0.2v, which I know is higher than the 0.1v ideal per this thread. I then asked to test a brand new alternator prior to purchasing it to see if its AC voltage was lower and it tested at 0.3v, so I did not purchase it and am basically stuck at square one. Any Ideas?Thank you,Josh

hello all, I stubbled across this TC lock/unlock forum while looking for the answer to this problem, I have read all the patch fixes, etc. and this fix seemed like the most promising. I have a 2002 Ram 2500 Cummins, auto trans, about 120,000 miles. I cleaned all the terminals then removed the 140 amp Alternator fuse, the TC issue seems to go away as described with the alternator out of the equation. Then I removed the factory alternator and had it tested, on their machine everything passes, I then asked for the details of the test and noticed the AC Ripple Voltage was 0.2v, which I know is higher than the 0.1v ideal per this thread. I then asked to test a brand new alternator prior to purchasing it to see if its AC voltage was lower and it tested at 0.3v, so I did not purchase it and am basically stuck at square one. Any Ideas? Thank you, Josh

Read my post in this thread #94 on 11/17/2012. Was explained to me and I found to be true, to measure your AC voltage on the vehicle with everything hooked up due to the fact that the voltage regulator is external at the ECM. Unless you have the right kind of equipment (scope), a bench test will pick up all kinds of AC noise from the testing machine itself, flouresant lights and you name it. Read my post. It explains the dilema I went through before my problem was resolved. Still reading 0.0VAC on my 2001 Dodge Cummins. I highly recomend staying away from Remanufactured Alternator. Go New and you will have a lot less trouble. New from the dealer $217.00 with no core charge. I paid $239.00 for mine from an Auto-Electric Shop because I didn't want to wait a week to get one in from the dealer. I can't tell you how many hours of frustration I put into sanding grounds, running wires and wrapping with tin foil and such before I bit the bullet and bought a new alternator. Of course that was before I ran across this thread and Mopar1973Man! Thank God I did, or I would probably still be chasing my tail!!!