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Discussion Starter · #1 ·
Pictured is the repair someone did to the thm400 attached to my 454 bbc. From what I can tell, this is a single terminal case connector for the electronic downshift signal. I tried a local transmission parts place and was sold what looks like could be the piece but there is no oring and if “I need one they don’t have it anyway” was the reply I got when I asked about it.
After peeling off the silicone it’s obvious this is loose and leaking. Do I just pull this out? I have the gm unit service manual and can’t find this mentioned. Do I access it when I drop the transmission pan? I’m sure there must be an oring. Anyone done this before? It’s a 1988 thm400.
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More for Less Racer
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Yes, there is supposed to be an o-ring in the groove around the inside half of it. Any standard rebuild soft parts kit wold have it, but I'm not sure how you would get it seperately

Removal of the plastic connector is from inside the pan, squeeze the little catch fingers a little and pull it out from the outside of the case
 

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Old(s) Fart
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New plastic connector bodies are available from any trans parts vendor for under $15, and come with the o-ring. You need to compress the lock tabs on the inside so the pan needs to be dropped to access it as well as to disconnect the wire.

 

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The plastic tabs may break off when removing the connector. For an outside repair , you can pull the connector out with vise grip pliers. Some Oil will drain out. Hook the wire to the new connector and push it is place. Little bit of lube on the new O-ring is suggested. The plastic bits left inside the pan will not cause problems. Been there , done it many times.
 
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Discussion Starter · #5 ·
Thanks for the help on this one. I contacted a local trans rebuilder and he has the oring. I will not go to that other place again. Anyone can see there should be an oring on that part.

The transmission is currently sitting on my garage floor. I just got the engine finished. Will do a quick fluid and filter on it before it goes back I’m the truck. So the pan will be coming off. No problem that way.
 
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