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817 Posts
I left for work and dropped my son off at daycare. I was leaving the subdivision and when I tried to accelerate, the truck acted like is was slipping badly. I stopped and tried reverse, which again barely moved. It threw the SES light. I had the wife come back and pull me back to the house.
Since I had put on a larger transmission cooler, I decided to restore it to factory before calling the tow truck. After putting the factory cooler back on, it worked just fine. The two codes were 700 - transmission control system malfunction and 747 control circuit step error. Of course, I sent my pred off yesterday to get it updated, so I had to go to Autozone to get them read.
The larger cooler was turned 90 degrees to the OEM due to having different fittings. I had to adapt to hosebarb and back to an AN -12 fitting. The in line was on the bottom and the out was on the top of the larger cooler. The overall height of the cooler was not any higher that the OEM cooler, so I would expect gravity to be a problem. Is th larger volume of the new cooler increasing the head enough to stop the pump of the Allison?
I have fittings being made so I can put the new cooler in the same orientation as the OEM, but they are not due for a couple more weeks. Is it coincedence that I changed back to the OEM and the transmission started working again? I don't think the hose or cooler are restricting the flow as both are bigger than the OEM cooler and lines. I also thought the cooler returned to the pan, so how would the pump be effected at all? Am I "vapor" locking they system? I do have the new NSBU switch. The engine and tranny had not come to operating temp yet. The other time it did a no go, the NSBU was replaced and all was well again. HELP!!
Since I had put on a larger transmission cooler, I decided to restore it to factory before calling the tow truck. After putting the factory cooler back on, it worked just fine. The two codes were 700 - transmission control system malfunction and 747 control circuit step error. Of course, I sent my pred off yesterday to get it updated, so I had to go to Autozone to get them read.
The larger cooler was turned 90 degrees to the OEM due to having different fittings. I had to adapt to hosebarb and back to an AN -12 fitting. The in line was on the bottom and the out was on the top of the larger cooler. The overall height of the cooler was not any higher that the OEM cooler, so I would expect gravity to be a problem. Is th larger volume of the new cooler increasing the head enough to stop the pump of the Allison?

