Trans temp and O/d flashes Randomly

[Eric Wilkinson]

Ok so I’ve read all the threads on this site about what could cause this and I’ve cleaned all connections, can’t find any loose or scuffed wires, had trans looked at by the pros and it was fine and still having this issue! Driving me nuts! Any input would be greatly appreciated I can’t keep throwing parts at this thing. Have changed out NPS, output speed sensor so far

 

[Eric Wilkinson]

Ok so I’ve read all the threads on this site about what could cause this and I’ve cleaned all connections, can’t find any loose or scuffed wires, had trans looked at by the pros and it was fine and still having this issue! Driving me nuts! Any input would be greatly appreciated I can’t keep throwing parts at this thing. Have changed out NPS, output speed sensor so far

It will flash when in park

 

[sag2]

What exactly is flashing? On the older trucks the OD switch would flash if the transmission was getting hot. What light is flashing, the OD off, or a message in the cluster or EVIC?
Also, what is the NPS?

 

[cerberusiam]

Need to know what year of truck also as that makes a difference on source of DTC's. Trans temp flashing randomly could be trans harness, VB harness, or trans temp gov pressure transducer. Could be a bad connection at ECM or PCM depending on year.

 

[Eric Wilkinson]

Need to know what year of truck also as that makes a difference on source of DTC's. Trans temp flashing randomly could be trans harness, VB harness, or trans temp gov pressure transducer. Could be a bad connection at ECM or PCM depending on year.

Sorry it’s a 2007 5.9

What exactly is flashing? On the older trucks the OD switch would flash if the transmission was getting hot. What light is flashing, the OD off, or a message in the cluster or EVIC?
Also, what is the NPS?

trans temp light in cluster and o/d kicking in and out
Neutral position sensor

 

[cerberusiam]

NPS is called a range sensor in the FSM.

If OD is randomly dropping you have a connection or short issue somewhere. The OD off and TH routines are a momentary switch to a ECM location, any type of stray voltage can cause them to vary. Also, the temp transducer failing will send hot trans signal to the ECM causing it to drop OD. Replace the transducer first before digging too much further.

 

[Eric Wilkinson]

NPS is called a range sensor in the FSM.

If OD is randomly dropping you have a connection or short issue somewhere. The OD off and TH routines are a momentary switch to a ECM location, any type of stray voltage can cause them to vary. Also, the temp transducer failing will send hot trans signal to the ECM causing it to drop OD. Replace the transducer first before digging too much further.

The Transmission shop told me that all that was good. That’s the first place I took it to make sure the trans was good. Can they tell if that good by just diagnosing the trans?

 

[Eric Wilkinson]

NPS is called a range sensor in the FSM.

If OD is randomly dropping you have a connection or short issue somewhere. The OD off and TH routines are a momentary switch to a ECM location, any type of stray voltage can cause them to vary. Also, the temp transducer failing will send hot trans signal to the ECM causing it to drop OD. Replace the transducer first before digging too much further.

Both lights will flash randomly sitting still not even in gear if that helps narrow it down at all?

 

[cerberusiam]

If those lights are flashing all is not good. The transducer and VB harness is the source of a lot of random problems just like you have. If the range sensor is showing park and the gears correctly it should not be an issue.

 

[Eric Wilkinson]

If those lights are flashing all is not good. The transducer and VB harness is the source of a lot of random problems just like you have. If the range sensor is showing park and the gears correctly it should not be an issue.

Would you change out the wiring harness to the transmission?

 

[cerberusiam]

Yep, 14 years old and subject to hot oil all the time. I would change the VB harness, transducer, and upgraded the gov housing and solenoid to the DNC piece.

 

[Eric Wilkinson]

Yep, 14 years old and subject to hot oil all the time. I would change the VB harness, transducer, and upgraded the gov housing and solenoid to the DNC piece.

Do you know where I could find the harness and what’s the DNC piece?

 

[cerberusiam]

Here is the gov housing and solenoid. Actually it is DNJ not DNC.

https://www.dnjcomponents.com/products/d-cf1

You can get the Rostra components here.

https://rostrapowertrain.com/transmissiontypes/48re-4-spd-rwd-2003-2007/

 

[Eric Wilkinson]

Here is the gov housing and solenoid. Actually it is DNJ not DNC.

https://www.dnjcomponents.com/products/d-cf1

You can get the Rostra components here.

https://rostrapowertrain.com/transmissiontypes/48re-4-spd-rwd-2003-2007/

Thanks so much for your help Ive been messing with this for over a week and you have been the most helpful! Much appreciated

 

[Eric Wilkinson]

Thanks so much for your help Ive been messing with this for over a week and you have been the most helpful! Much appreciated

Does the DNJ replace the OEM gov. And solenoid

 

[Ozymandias]

Yes it does.

 

[Eric Wilkinson]

Yes it does.

Ok thx again

 

[cerberusiam]

Yes, it cleans up the tight passages in the OEM so it doesn't sludge up and exposes the solenoid to more uniform pressure for accuracy. The solenoid is rarely the problem rather the OE gov housing is the usual source of issues. The transducer is much more the issues as they are just junk with a finite life expectancy. The Rostra units are the better ones out there.

 

[Eric Wilkinson]

Yes, it cleans up the tight passages in the OEM so it doesn't sludge up and exposes the solenoid to more uniform pressure for accuracy. The solenoid is rarely the problem rather the OE gov housing is the usual source of issues. The transducer is much more the issues as they are just junk with a finite life expectancy. The Rostra units are the better ones out there.

So you would go with the Rostra instead of the DNJ?

 

[Eric Wilkinson]

Is this all I need for that?