I have 99 ram 5.9 4wd 46re trans my issue is that the od off light is on and so is trans temp, had to a trans shop they found nothing internally wrong and said they had swapped a pcm from another into it and it went down the road fine. So I ordered a reman pcm and it was flashed reinstalled it and bam trans temp and od off light on immediately still. Scan tool says my trans is at 300 degrees, it drives fine other than not going into OD. I also have no power on the orange wire that goes to the OD button. I'm new to Dodge transmissions so not sure where to go from here..I've read that if pcm thinks trans is hot it will go into limp mode and stay in 2nd but this isn't the case mine will go all the way up into third but never 4th/OD. The truck has also had the cooler by passed and a after market installed but check ball is still in the line. I also noticed a green line going from t case I think up back of motor I assume it's vacuum line and it's just sitting there not sure if it's related, I can't see to see where it would go if it has in hooked. Any help is appreciated I'm out $300 so far with the pcm and still where I started.

 

Moved you over to the 2nd Gen section. Good luck with your trans issue.

 

If you are seeing the issue with another pcm i would think the issue is the temp sensor in the trans.

If you seeing 300* as soon as you start it that confirms the temp sensor in the trans is bad. Time to find another trans shop!

 

temp sensor is in the Governor pressure sensor. From what I understand it's an easy swap. Also, make sure the connectors are sealed and water proofed. I had an issue with my transmission during heavy rain where the temp lite would come on. Ended up being water in the connector. Dielectric grease solved the problem

 

Temp sensor is with the overdrive lock up solenoid not the pressure sensor and solenoid. You need to drop the valve body to replace it.

 

Temp sensor is part of the pressure sensor.

 

My bad! I must be going senile.

 

I've been there for a while. It has its advantages.

 

Part of the Transmission Solenoid Assembly. Connected to Violet wire on pin 8 of the connector.

 

TRANSMISSION
TEMPERATURE SENSOR
DESCRIPTION
Transmission fluid temperature readings are supplied
to the transmission control module by the thermistor
(Fig. 246). The temperature readings are used
to control engagement of the fourth gear overdrive
clutch, the converter clutch, and governor pressure.
Normal resistance value for the thermistor at room
temperature is approximately 1000 ohms.
The thermistor is part of the governor pressure
sensor assembly and is immersed in transmission
fluid at all times.
OPERATION
The PCM prevents engagement of the converter
clutch and overdrive clutch, when fluid temperature
is below approximately 10°C (50°F).
If fluid temperature exceeds 126°C (260°F), the
PCM causes a 4-3 downshift and engage the converter
clutch. Engagement is according to the third
gear converter clutch engagement schedule.
The overdrive OFF lamp in the instrument panel
illuminates when the shift back to third occurs. The
transmission will not allow fourth gear operation
until fluid temperature decreases to approximately
110°C (230°F).