Torque Converter lockup

[k4rbm]

I first discovered this about 2 years ago. The truck, 2500 1999 diesel, would shift into 4 gear and then the tc would unlock for a bit then repeat. I have the mistery switch so I would lock it up and no problem so I know it is electrical. I have read years back about disconnecting your battery for 24 hours and it fix the problem. I laughed but tried it. It worked for 6 months no problem then it started again. So I repeated the process because I am building a house right now and don't have time to persue it. Well I just did this again only now I just disconnect the battery's and short the cables togeather for a couple of hours and it does the trick. Well, this time it didn't work. I found a tsb way back that is suppose to fix this problem. TSB 18-033-04. The problem supposedly is that the Throttle position sensor gets noise in the ecm and causes the problem. I have read horror stories about 3 tranny replacements and such and still have the problem. I refuse to spent a dime until I know what the problem really is. Sam and Dave on the syndicated radio show were not much help on this either. Is there anyone in Dodge corparate that would have any idea of what the cause really is. this is a very common problem with the Dodge. Replace the tps? That is what I hear most but don't believe it. As I speak I have the batteries disconnected again and will see if this fixes it for another 6 months.
I pulled the tsb so long ago I can't find any info that says what this tsb does. Supposedly reflashing the ecm will fix it. Any help out there??

[scoutinkeith]

well, the ram that I used to have had the 360, but the TPS works basically the same way. it supplies a voltage signal to the computer to tell it how far open the throttle is. think of it like a dimmer switch on a house hold light, at idle would be like the light turned down dim, and wide open throttle would be like the lights turned all the way up. every time you push the accelerator pedal it's like turning the lights up(higher output voltage from the TPS). over time, and from constantly being moved, the TPS will develop bad spots in the contacts that regulate the output voltage signal. the computer sees these bad spots as either a spike or drop in voltage, which it interperates as the driver either letting off of the accelerator, or stomping on it. in either case, the computer then unlocks the torque convertor.
you can test the TPS if you have a volt meter, however I'm not sure if the diesel wiring is the same, so I don't know which wire you'll want to test(on the gas engine rams, it is an orange wire that is in the center location on the TPS). also on the gas engines, the output voltage should be low at idle(0.5 to 1volt) and steadily go up to about 5 volts at wide open throttle. with the positive lead of the volt meter hooked to the output wire on the TPS, and the negative terminal hooked to ground, you will be able to watch the voltage as you slowly open thethrottle. if the voltage drops off or spikes wile you are opening the throttle, then it is bad.

I also remember hearing something about a sevice bulliten, I thnk it had something to do with the routing of the signal wire from the TPS to the computer. if it's to close to other electrical components, it's posible for the computer to get a false reading even if the TPS is working properly.

hope this helps ya out some,
Keith

[troy1]

99's have a higher than normal failure rate for the output speed sensor on the trans super easy fix... have you noticed any thing with the speedo?

[k4rbm]

Thanks for the tip on the tps. I have read the same thread on another board and I have about decided to check it out. Makes since but odd that the old battery disconnect trick worked for about a year but now I am driving mostly with the old trusty mystery switch. Yes there is a bulletin out about rerouting the wire I did read that a long time ago. I will check out the tps with voltmeter. I am a retired A.T.T. tech support guy and a ham radio guy so electrical is not a problem if I just under stand the program. Another thing that comes and goes is the IOD fuse. Every year or so I have to pull the fuse out at night or it will run my battery down. Haven't figured that one out yet but hasn't been a problem lately. Now that circuit is really tricky.

As far as the speedo it's fine no problem.

Thanks