Rear Diff Won't Lock

Hey guys,

I have a 2012 tacoma off road, with the electronic locking rear diff. I never had to use the rear diff ever since I've owned this vehicle but recently had to engage it. When I went to engage it while in 4lo, the rear diff dash light would not turn on. There was no blinking light, nothing. I looked on other forums and in all that I read I saw that other people's rear diff dash light would blink, signaling that the diff was not engaging. Before I take off the actuator and mess with that I was just wondering if there could be another issue since mine won't event light up the dash light.

Thanks in advance

 

Have you owned the truck since new?

 

Does it throw any codes?
Is it a dummy button?

 

2nd gen 4wd system isn't capable of setting codes or communicating with a scan tool.

That's kind of why I wondered if he owned it since new. Possibly the switch isn't hooked up/it's not equipped or someone installed the incorrect 4wd ECU.

 

I bought it used and have had it since 2016 with 80k miles at the time. Right now it's about to hit 250k miles. How could I check the 4wd ecu and check if the diff lock is hooked up? any advice would help

 

Look at the rear diff and make sure the locker is present.

The 4wd ECU can be found to the right of the glovebox, see the thread below for info on how to access it. If you can get the number off it we can verify it's the correct one.
https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/

 

I know the locker is present. I'll go check the 4wd ecu and report back

 

The diff locker actuator is there and doesn't look beat up. The 4wd ecu number is 89533-04021 and the number right below that one is 363811-11540.

 

Yea that's the non locker ECU, the one with the locker should be 89533-04011

 

Oh that's just great
Lol on the bright side I don't have to tear apart the actuator.
Is this the right part?
https://www.ebay.com/itm/3058055027...fl9hd0itsi&var=&widget_ver=artemis&media=COPY

 

Should be, same part number as mine in my 14 TRD OR and my locker works.



The one I have in the 4wd simulator I built is a non-locker version and it's the same part number you have.

 

Thank you so much!!!
I hope you have an amazing 2025

 

Good luck, let us know if you need anything else.

 

I never would have thought to check the ECU. Great job!

 

Well considering there's no light action there's not many possible causes, the most obvious and easiest to check is if it has the correct ECU. If the ECU was correct we would be checking the switch input and the output to the indicator light.

 

My mind went straight to switch/electrical issue given it's a 2012.

 

get into 4l in Neutral. then engage the locker button. and do this off pavement, grass, dirt etc

 

Either you use it, or you lose it.

I bought my 07 new and drove it every day until 2016 when we needed a bigger truck. I bought a F150 and drove it. We kept the Tacoma, and my wife drove it every day until 2020 when we bought her another car and kept the Tacoma. When I drove the Tacoma 4hi, 4lo, and the rear diff were used regularly to keep them working. During the 4 years my wife drove it 4hi was still used on occasion, but the rear diff was never locked.

After 2020 I went back to driving the Tacoma every day and we only use the big truck when we need a big truck. Initially mine did the same, the diff simply wouldn't lock. This was during the Covid lockdowns. Everything was closed, but turkey season was open, and I could socially distance. I hunted almost every day of the season driving about 10 miles every day on dirt roads getting into and out of where I hunted.

I started driving in 4lo and kept hitting the button to lock the diff. After about a week it started working again. At 1st sporadically but by the time turkey season was over it was back to normal. I check it regularly and it's still working.

 

Well hopefully the actuator still works but we need to get the correct 4wd ECU installed first.

 

If anyone is selling the 4wd ecu 89533-04011 please message me
I've had no luck with Google and Facebook marketplace.
Will be hitting up scrapyards tomorrow