Question about transmission and wiring harness corrosion

Hey guys, I'm hoping somebody can answer my question or if it has already been asked, to direct me to that forum.

I have a 2006 Tacoma, TRD sport, 170000 kilometers. My truck came out of gear while driving on the highway going around 100km/hr and engine light came on immediately - code p0986. I slowed down to 50km/hr and was able to drive to toyota without it coming out of gear again. Toyota did their diagnosis and found corrosion at transmission (probably due to the salt on the roads they use in the winter here) and they recommended replacing transmission and main wiring harness. They said cleaning the connections would probably fix the problem but they are not able to do it. Instead they put dielectric grease on the connections which worked for a little while but a couple days later it happened again.

I want to try cleaning the connectors myself but i can't seem to find a write up to go about doing this. I noticed two grey connectors on either side of the transmission and I'm wondering if those are the connectors i have to clean, or if there are more. I would greatly appreciate it if somebody could steer me in the right direction. Thanks!

 

This is the connector at the transmission and the ECM and what you need to check. If both are good it says to replace the ECM. I agree the harness connector at the transmission is the likely cause due to corrosion. Try and clean those connections at the transmission and seal the connector with dielectric grease.

If you get it clean. DO NOT use dielectric grease inside of the terminals as it is an insulator and will inhibit current flow. Use dielectric grease on the connector sealing surfaces to keep water and salts out of the connector.

 

Here is the internal cable for the transmission:

http://www.customtacos.com/tech.old...6toyrm/06toypdf/06rmsrc/rm2006ta/02700510.pdf

 

This video talks about dielectric grease here: https://www.youtube.com/watch?v=yuKAmaIkA-U

 

Thanks for your help guys

Jimmyh, the wire inside the actual transmission - is that the transmission wire harness that I have to clean? Or is there some connections outside the transmission that I have to clean such as this one? (see picture) which is on the passenger side.

 

The Cable run inside of the transmission is for the solenoids ( I think there are 7 of them ). This comes out of the transmission to a connector like is displayed in the graphic above. Into that there is a vehicle harness that plugs into it that connects to the ECU.

Like this:

Solenoids-----------Internal Transmission Cable-----|Plug on Transmission |----Wire Harness to ECU

 

Just wanted to give a little update in case anybody was interested - I haven't had much time to fool around with it since last weekend but I finally found the corroded plug (not the one in the picture i posted earlier) I have two pins broke off due to corrosion on the transmission male connector, so I will need a new transmission wire. I checked with Toyota again and they said I should also replace the female plug from the main engine wiring harness, or just replace the entire engine wiring harness but they could get really expensive. I wish i didn't have to touch the engine harness but they think the corrosion will continue to seep down into a new transmission cable. They also think the broken pins are still in the female connector. I will buy the transmission cable brand new and try and find a scrapped Tacoma somewhere so I can get that female plug. Wish me luck

 

Did you ever end up finding a salvaged wire harness? I just ran into this same problem with my ‘08 Taco and I’m scouring the web for a solution. Any advice is much appreciated.

 

Resurrection of this post I’m going thru the same problem I think , will be digging deeper tomorrow . Having delayed engagement from P to D . Replaced neutral safety sensor after stalling issue . Stalling no more ........now the delayed engagement .

 

@lynyrd3 I wish you luck with your issue! My main engine wire harness/transmission wire harness connection was corroded and both needed replaced. I was able to find an aftermarket female plug on eBay to splice into the main engine wire harness so I didn't have to replace the whole thing. I also had the transmission wire harness replaced and all the work was done by my local German Toyota dealership. It's been a couple months and 2nd/3rd gear still shifts a little hard for my liking. I need to double check the solder job, but generally speaking Germans have pretty solid workmanship.

 

Welcome to TW @tacomamma Thanks . Here is what happened today .Took it to my guy who replaced the sensor a couple months ago ,was going to drop the pan today . Luckily when he went to move it there was delayed engagement so he hooked up his computer to the OBDII port and low and behold he figured out the sensor he installed was not adjusted correctly . Just like I asked him a month ago .. so I just put around 120 miles on it parked it and moved it 6 times and no delayed engagement .So I am hoping this took care of it . I knew it would be something stupid . So now we will still be dropping the pan and putting a filter and doing a refill with whatever comes out of the pan and a bottle of Lubegard for safe measure . I asked the dealer 2 weeks ago when they had it for 3 days to check the adjustment on that sensor . I guess they couldn’t be bothered .

 

No more delayed engagement

 

Do you have the link to where you found it on Ebay?

 

Are the connector terminals copper?

You can use a mixture of one tbs. Salt to one cup vinegar to soak copper and clean it, then neutralize the acid with water and baking soda mix. Rinse, then dry completely, dielectric grease as recommended.

I do this on my old vw's a lot and it works well, not sure if the new Toyota would like it though. It cleans without physically damaging pins.

Best to all.