47RE Shift Problems

[KrustyKruiser]

Hello Everyone:



I have done a fair amount of searching to try any learn about issues with this transmission, but am still struggling to find an answer/fix.



I have a SO 2003 5. 9 with a 47RE 4WD. She has 115K miles. Just before Christmas we were driving down from the mountains (not towing) and stopped at a convenience store; when we drove away we had no 1st gear and no OD. Taken her out several times and tried starting manually in 1st, but it always starts in 2nd. No matter what speed I get up to (and let off the pedal) she will not shift into OD. Given that it was working fine and then both first and OD stopped working I doubt it is a mechanical issue (when I did the transmission service there was no hint of excessive metal flakes in the oil or excessively burnt oil, etc.



So far I have replaced the shift solenoid, gear sensor, and transmission governor pressure sensor. I have adjusted the bands. I have looked at the PCM wiring harness and cleaned the connectors and can find no corrosion or bad wiring. There are NO trouble codes being thrown.



When I bought this truck used 4 years ago it stopped upshifting into OD. It was still under warranty and the dealer replaced the TCM - or at least that's what was on the work order.



I am hoping someone may have some ideas. I have read about ECM reflashing, etc. - is there a testing service out there to diagnose issues? Is there a separate TCM?



I am reluctant to take it to a dealership - I'm not very confident of their abilities



Thanks for taking the time to read this and let me know your collective thoughts.



Cheers,



Andy

 

[cerberusiam]

Did you replace the gov pressure solenoid?



Have you checked the transmision relay fuse in the fuse box?



The TCM on that year of truck is part of the PCM located on the passenger side firewall. That may be your issue again. The ECU can store DTC's that will take the appropriate scanner to read and you will NOT get a CEL.



The 03's have a TSB for corrosion on the ECU connections, another thing to check and think about.



You can wire a mystery switch to the OD to verify the trans is functional and it is an electrical issue.

 

[KrustyKruiser]

Thanks for the reply Cerberusiam:



Yes, I checked all fuses and relays, and replaced the pressure solenoid. I saw the TSB and cleaned/inspected the wiring harness and connectors.



I will do some more checking with the wiring and see if the OD switch is at fault. However, given that I have issues with 1st gear also I think there is something else going on. Thanks for the head's up that the ECU stores trouble codes that are not always displayed with a CEL. I have not tried hooking up my OBD scanner. Hmmm...

 

[TCDiesel]

Did you replace the pressure sensor also? or just the soleniod?

 

[cerberusiam]

The other thing you need to check is the trans control harness and how it is routed to the PCM. On that setup it went by several sharp body ridges and mounts that would fray the wires in the harness and cause all sorts of mischief. You about have to disconnect it and pull it out to see if there are bad rub spots.