P0712 Error and flashing O/D off light

[Mikerson]

I dropped my van off at Les Schwab to have them help pinpoint a persistent suspension clunk (they couldn’t figure it out, more later) and when I got it back, I had the O/D light on the shifter flashing. Just got the code read. P0712 which is a temp sensor low signal error. Anybody have this before? Ideas on what could cause this besides a bad sensor?

Background on van/tranny: ~145,000 miles. 4r70W trans was rebuilt and converted to 4wd with the different output shaft about 15,000 miles ago. The trans guy insisted on installing a shift kit. “I do this in all my transmissions, you’ll like the way it shifts.” I actually hate it, but anyway…The torque converter is a new HD unit installed at the rebuild. I replaced the low quality aftermarket trans filter the shop installed with a motorcraft filter about 6000 miles ago. It is full of motorctaft Mercon V. Currently trans shifts and drives fine with no problems.

[1der]

Here is the connector for your year. If you have not already, perhaps check the connector for good contact.

[Mikerson]

I will try that. Thank you!

[arctictraveller]

I just had the exact same issue with my 4r70. It was the bulkhead connector that transitions the wiring harness from inside the tranny to the outside wiring harness plug. It leaked ATF into the contacts. You could try pulling the plug and cleaning with contact cleaner. I had mine replaced

[Mikerson]

Thanks AT! That is exactly my problem too. Connector looks like it took a bath in ATF! 😡
Did you do this repair yourself? I assume the pan has to come down and the bulkhead connector installs from the “inside” of the trans. Do you have a part number for the replacement you used? I want the best quality possible because I don’t want to do this again.
-Mike

[Mikerson]

Not too many parts options out there. Ordered the Rostra and a wiring harness.

[arctictraveller]

Sorry for the slow reply, I’m on a trip with limited internet. Anyway, in my case the transmission was under warranty, but Ford refused to make the repair because the part is no longer available directly from Ford, and they refuse to use an aftermarket part. As a result, I had to pay an independent transmission shop to install it. And yes you’re correct, the pan had to come off, the filter and I believe the valve body before you can get to the connector. It’s probably not that difficult but way too messy for me to attack. It’s funny that Ford said the part was no longer available, when the shop i used have them in stock. Best of luck.

[Mikerson]

Originally Posted by arctictraveller

Sorry for the slow reply, I’m on a trip with limited internet.

No worries and thanks for getting me pointed in the right direction! This past weekend I tore into the trans and replaced the bulkhead connector. Seemed to solve my flashing light problem. While it’s not a hard job, it is very messy. For others that end up with this issue, I can point you to a couple of YouTube videos to get you oriented with a good removal/install procedure.

Fordtechmakuloco
Jmod guy