4r55e p0707 only at idle.

[phix-]

Hey EF,

Recently had my battery disconnected to do some work. Truck has been driving fine for about a day. Though I now get a flashing O/D OFF light only when sitting at an idle or complete stop. I apply light throttle and the light turns off/stops blinking till a come to a complete stop again. Though I did not have this issue before doing exhaust manifold gaskets. Trans was rebuilt about 1yr ago. Thoughts?

 

[phix-]

Update:

Further testing yielded the following:

- Full EEPROM reset (unplugged the battery)
- O/D OFF (p0707) is only present at startup when stopped.
- First drive after EEPROM reset, O/D OFF flashing occurs only for about first 10min.
Note: Still only at a complete stop.
- Second drive after EEPROM reset, 10min O/D OFF flashing occurs moving or not.
- Truck was placed in park, engine shut off, turned on. O/D Flashing does not occur even at a stop.

At this point, I am pretty sure the park neutral safety switch is suffering low voltage at startup. As well as during the first 10min of the drive, harsh engagements due occur during this time. There is a pretty odd 3/4 down shift that occurs after you take your foot off the accelerator and allow the truck to coast to a lower speed. Will update once the switch is replaced for anyone else to find. This code/information seems to be not very documented to confirm when the switch should be replaced.

 

[phix-]

Update:

Changed the park safety neutral switch. Clean up the connector at the park safety switch. Flashing O/D is now more persistent with the new sensor/safety switch. It mainly happens when sitting at a dead stop, sometimes while coasting, after I start accelerating from a stop the O/D light stops flashing. It sometimes does not come on at a dead stop. One thing to note, my alternator was disconnected to install some exhaust manifold gaskets. I've checked the alternator at an Autozone, I've checked voltage at a power cap I have in the trunk when light is on and off. Getting a solid 14.0 to 14.2 at idle.

Other things to note:
Battery was replaced due to bad cell that would cause the truck to need a jump if it sat for more than 3 or 4 days. Alternator is a HO 200amp aftermarket alternator, not exactly sure how long I have had it but 4yrs+ is an easy assumption. Shift behavior is weird, for the most part the tranny behaves driving around. I've had it on the high way and it was ok, then would rev and what I assume is come out of gear. Even with the new safety switch. I've searched and cannot find anyone who was able to remedy an issue like this one. Any help at this point is greatly appreciated.

 

[phix-]

Alright, so.. all of the above is not part of this issue. For anyone who stumbles across this post. Check the grey connection that is responsible for connecting the engine harness to the external harness. In most cases, the connection falls out of the body groove it uses to keep it mounted or someone moved it or it breaks. The connection ends up sitting on the bell housing which when it comes to temp causes odd behavior (shifting) including a flashing O/D light. That may or may not disappear as you accelerate forward and return when at a flat stop.