Solved - Persistent Transmission OD/4th Gear Issue

[Jack90210]

Wow, this is great intel. Appreciate you adding this diagnosis to the hive mind!

 

[geoffunkel]

@geoffunkel Great deep dive! What was the part number for the Lo Switch? Issue hasn't popped up since I swapped ECU, but that doesn't mean it won't. At this point, I'm happy to put in a Lo switch for added peace of mind.

Sorry for the slow response, was out of town a few days. The part that I used was Beck/Arney 2011788 from Rock Auto, however I wouldn't recommend it because it failed within a few months of installing after I replaced my failed original one (different type of failure, was always open circuit).... Currently seeking other brands.

The easiest verification like I mentioned is waiting until the problem occurs and then just getting under the truck and disconnecting the the switch to see if the problem goes away. It's pretty easy to get to at. It goes in at about a 45 degree angle near the top-rear passenger side of the transfer case (not the vertical one, that's the neutral sensor). I found it a little easier to loop my arm around the driveshaft to access it and make it (slightly) less likely to burn myself on the exhaust lol.

For the record, this is the same exact part number as the CDL switch. The Transfer case neutral switch is very similar but has a different connector. My LC is a MY 2000. I personally doubt that any of these part numbers changed from 1998-2007 but I cannot confirm.

 

[JohnMed]

I also replaced those switches with beck arnley ones last year. I just yesterday went on partsorq and found the OEM parts and purchased factory ones from Toyotopartsdeal

 

[Bisho]

I used the Beck/Arney switch for about the last 80k miles and still going strong. You might try removing and cleaning it, maybe something got in there to jam it. They are very simple switches.

 

[geoffunkel]

I used the Beck/Arney switch for about the last 80k miles and still going strong. You might try removing and cleaning it, maybe something got in there to jam it. They are very simple switches.

Finally got around to replacing my low range switch last weekend. I electrically tested the new one before installing and it checked out good. I was messing around with the old Beck/Arney one with an ohm meter and it is for sure bad. Nothing jammed in there. When depressed it closes the circuit as designed and reads around 1 ohm. But sometimes it doesn't go full open circuit when the plunger is released. It reads anywhere from 5-200 ohms, sometimes open circuit; it's all over the place. Clearly something wrong internally in the switch, maybe ATF got into the internal electrical connections somehow. Guess I just got unlucky and got a defective one. The one for my CDL has been working fine for the last couple years.

Anyways, the old one was bad and I have a new one installed and all is well so far.