I am in need of some answers. I have a 1998 2500 with a 24 valve. I bought this truck off a guy about a month ago. The truck has 125k and the engine runs great but my problem started when my transmission started to give me problems. When driving between 45-50 mph the transmission would shift into overdrive then back to 3rd. It would continue this until you're speed reached under 45 mph or the rpm's where under 1500 or if your speed was over 60 mph and the rpm's were above 2000. After that the truck and tranny drove fine. I was talking to a few tranny guys that I have know for awhile and they said that 98 dodges are know for this problem and most of the time the PCM is going bad or is bad. So I changed the PCM out with a new unit from dodge. Then I had the dealer burn the VIN and proper milege into the PCM. The truck had never ran right since I changed the PCM out. Here is what my problem is now. The transmission when put into drive stays in drive. What I mean is that from a dead stop the transmission never downshift to a lower gear it just stays in 3 rd all the time. You can manually downshift and the truck drives fine. Also I have no overdrive what so ever. So I dropped the tranny and rebuilt the entire unit including every solenoid, every clutch pack, an entire rebuild from front to back. I installed the tranny back into the truck with all new fluids, to find out the I still have the same problem. I just dont understand that the transmission worked fine until I changed the PCM out now I am having problems. I think either the dealer burned the wrong flash into the PCM or the PCM is faulty. Common sense says that if it was working bdfore and then I changed the PCM out and now it is not working, well . Also if anyone knows exactly what all the PCM controls I would appreciate if you could shoot me an email. If anyone had any ideas please let me know. Thanks guys

 

The "3rd to 4th back to 3rd" issue you described is most likely the torque converter locking and unlocking. Viewed with a scan tool you can see the pcm making this happen. Cause is from electrical noise that the pcm is seeing as a signal thus unlocking the converter. Search around this site and you'll see lots of reading on the subject. On the trans overhaul not sure why you went to that length, but at this point you need to find someone who knows what they are doing with a DRB and start doing some diagnosis. Sounds like you have an input issue with your governor psi sensor, but that needs to be looked at with a scan tool.

 

Thanks J body for the information. The tranny rebuild was easy, its all the electrical that I hate. Yeah I'm not sure about the input prob but I think your idea is on the right path. The tranny overhaul was easy and I feel better that I re-freshed the system because who ever had the truck before had the tranny rebuilt and who ever did the job did not assemble the tranny correctly. Now everything inside is properly installed and back to normal besides for the current prob. But I never had this prob. until I changed the PCM so I keep going back to that when I try to figure out what is going on. If you know anyone who might know send them my way. I think I am going to take the PCM back out and take it to the dealer and let them check it. Also mopar had technical # that I am going to call on Monday to see what they have to say.

 

Taking the PCM out will do no good. It really needs to be in the vehicle for 99% of the techs to diag them. I have a "bench tester" that I made but it will only allow you to see if the module is capable of communicating with the scan tool (drb in my case). Your problem of "not shifting down" sounds alot like the gov psi transducer or solenoid which have been a problem over the years. Hard to give you the right info without seeing what you are up against personally.

 

I understand exactly what you are describing but I have replaced the governor pressure solenoid along with everything else under the sun that you can replace while undertaking a complete overhaul. I might have a problem with the correct voltage at the connector. I need to find how mcuh voltage I should bee recieving from the PCM to the connector and when the voltage signal is going to be recieved at the connector. Like if there is a constant voltage or if the signal is recieved once the truck has reached operating tempature or if the voltage increases during driving operations.


Electrical is frustrating!

 

Here's the deal. I had the truck put on the scanner and this is what it said. I have 4 codes all together.

1682
1693
1765
0216


I understand what two of them are but I am not sure what 1682 and 1693 are? It doesn't show them along with all the other codes. Maybe one of you guys has a clue. If anyone has any info on any of these codes I would appreciate any advice. Thanks again

 

This is what I found out.


1682-Metering oil pump malfunction

1693-Turbo charge control circuit malfunction

1765-Timing solenoid circuit malfunction

0216-injection timing control circuit malfunction

Could someone explain what the codes mean in detail please. Thanks again guys.

 

Well for one, it sounds like your injection pump is going out according to 1765 and 0216 codes. Two, the 1693 is just a companion code saying that another code has been set in the computer. No biggie. The 1682 sounds like it might be your problem. I'd have all of the codes cleared and see which, if any, come back.

 

Thanks bigblue for all the info. I wonder if I should change the oil sending unit? Maybe that is causing the 1682. So I need to change the VP44? Should I check the fuel pressure before I change the injection pump? Also what about the lift pump? Should I change both of them? I should get the codes cleared then see which ones show back up. That should hsow what my prob is right?

 

This has to be an electrical problem........... I am not sure but I need to find an electrical schematic that shows wire identification and voltage. Neither one of my manuals have any specific information on the electrical system on my truck. Does the dealer have anything of this nature? There are no codes that would be keeping my tranny from functioning properly right unless I am overlooking something? Also the correct maxium oil pressure is ??? I guess I am just going to keep trying!

 

Ok I cleared the codes and this is what I found.

Still have the 1693

1765-trans voltage relay circuit either has an open circuit or a short

0753-shift solenoid A circuit electrical


So either I have a short or a ground problem. That is what I am thinking. Does anyone have a clue of where I can get a wiring diagram for the electrical system. I also need to find what my voltage ranges need to be when the ignition is on and when running. If anyone has any ideas please let me know. Thanks

 

The shop manual can be bought at www.techauthority.com

If you take a look ath teh PCM connectors and the single connector on your tranny you can easily detemine whether there's a short by unplugging both ends (All PCM connectors and the tranny connector) and looking for a short between cables or short to ground on each pin of the connector. There should be no continuity anywhere with both ends unplugged. I'd also check the pins and the female ends on the connectors for good contact.

HTH

AlpineRAM

 

Thanks for the site and info AlpineRam. I didn't find the exact manual on techauthority but I am going to give them a call. Thanks again

 

It may seem over simple?

I had trans trouble.
It was diagnosed as the PCM.

Lucky for me I checked the Alternator brushes and they were almost gone.
The brushes were arcing and causing noise in the electrical system.
The Atl. light was not lit. but the brushes were still causing noise.
100.00 for a re-built unit and it was like driving a new truck..

SFB

 

Yeah I changed my PCM and that is when all the real trouble started. Come to find out my alternator and batteries went south so I had to change them also, but ever since I changed my PCM and had the dealer flash it I have had nothing but problems! See I just dont grasp the concept that everything was working fine besides for the locking and unlocking of the torque convertor. Then I changed the PCM and now I have 3 codes and my truck is not driveable. I took my truck back to the dealer to see if they had flashed the wrong code and they told me that it was the correct code. I still think it is either a bad PCM or they didnt flash the correct code!!! Thanks for all the info San