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sprinkles08, ASE Certified Technician
Category: Transmissions
Satisfied Customers: 22970
Experience:  Chrysler/Dodge/Jeep master tech ASE Master and Advanced Certified, Chrysler/Dodge/Jeep Master Certified, Trans Specialist
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I've got an 03 Dodge Ram 3500 with the 48re. Transmission is

Customer Question

Good morning Richard,
I've got an 03 Dodge Ram 3500 with the 48re. Transmission is in limp mode - 3rd gear. No 1st, 2nd or OD. Once in a while it will shift normally, then goes back to limp mode. Codes are P0642, P0483, P0700. I thought it might be the PCM connections, so I thoroughly cleaned them. I also went over every ground wire and connection plug to the trans. I replaced the pressure solenoid and regulator in the trans. Tranny has about 40K on a rebuild, pulls strong in all gears with no slipping or flares.
Submitted: 1 year ago.
Category: Transmissions
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

The trans is going into limp in. when the powertrain control module sees an issue that can cause damage or it thinks it doesn't have complete control it will shut off power to the solenoid pack and lock you in third gear. Possible causes are the solenoid pack, governor solenoid, wiring, the trans relay, integrated power module, or possibly the PCM.

The codes you listed are all set in the ECM. The first step in diagnosing the problem will be to see what codes are in the PCM, the module that controls trans operation. Do you know what the rest of the codes are?

Customer: replied 1 year ago.
Everything you told me I am aware of. Solenoid pack is fine though, transmission shifts fine when shifted manually. I need help with troubleshooting the trans. I suspect a connection between the PCM and the harness but I am insure how to troubleshoot it.
Customer: replied 1 year ago.
Only the three codes I Iisted are showing up
Expert:  sprinkles08 replied 1 year ago.

These codes are set in the ECM, you need to read codes from the PCM to begin diagnosis. What did you read codes with?

How did you determine the solenoid pack is fine?

Customer: replied 1 year ago.
I don't have a pcm code reader, I only have an OBD II reader so I can't read anything past the P0700 generic code. I don't know for certain the solenoid pack is fine, but the truck shifted perfectly today pulling 12k for 150 miles. Its like it has good days and bad.
Expert:  sprinkles08 replied 1 year ago.

Without knowing what codes are set in the PCM you'd have to either start testing blind or replacing parts.

Have you tried the key cycle method?

Customer: replied 1 year ago.
that retrieved the same ECM codes I pulled with the OBD scanner. So you're saying I need to take it to the dealer? I was hoping this service would allow me to avoid the dealership.
Expert:  sprinkles08 replied 1 year ago.

Any shop would be able to read the codes.

If you have the ability to do electrical testing you can try testing the solenoid circuits or you could try replacing the solenoid pack. If the governor solenoid has been replaced then odds are the solenoid pack is the issue. Wiring, the governor solenoid, trans relay, and IPM are all possibilities but the solenoid pack is most likely. The resistance of the two solenoids can be tested, but it has to be done at the time the trans is in limp in for testing to be valid.