2009 TRD offroad won't go into 4WD

You could also jack up the front and see if the transfer case and/or ADD are engaged or not.

 

Right now it is not doing anything good, but I will definitely check on Sunday.

 

I am going to follow your advice and go right to the 4WD ECU behind the glove box. I'll let you know what I find. I assume the F13 B connector is the top one.

 

Correct, if you notice the 2 plugs are different.
1 is a 24 pin (F12) the other a 26 pin (F13).

Also, pins 3 & 4 are “bigger” on F13 - That way you can be “extra” sure you are on the right one

 

So here is my up-date. I got up early this morning and before I left for work I was going see if the front driveshaft was engaged to the transfer case, then jack up the front and see if the front differential was engaged or not, like someone wisely suggested. So I start the truck, put it in 4H and it goes right in, put it back into 2H and the 4Lo light blinked so I turned the key off and started the truck again and the 4Lo light was off. When I stopped for coffee on the way to work, I tried again, this time into 4H and back into 2H without issue. I tried again on a 45MPH road just before I got to work, again 2H to 4H and back again, no issue. When I got out of work, I tried it again in a gravel parking lot, 2H to 4H and drove away making a turn and all 4 wheels had power because I could hear gravel crunching. I tried at least 4 more times on the way home from work, all without issues into 4H and back to 2H. I was all ready to start probing connectors tomorrow. I studied the write-up and printed out the plug pictures and expected voltages. Now I don't know what to do, $hit or go blind, maybe I'll close one eye and fart, HAHA. Any ideas???

 

It could have been one of the contacts from the limit switches that was corroded and you exercising it wiped it clean enough for it to function again. That’s why Toyota recommends exercising the 4wd system at least once a month. You must exercise the actuators, if not you, than get a friend to do it

 

Yeah, I guess so, honestly, it's been a while since I put it in 4WD. From now on I will do it on a regular basis. But, I have the detailed write-up from you guys and I will keep it on hand just in case. Thanks again for all your help. Very informative. Thanks again, JP.

 

So, in my haste to declare victory, while laying in bed last night (not sleeping as usual), I realized that I never checked 4WD LOW. So this morning I gave it a shot and it worked!!! Even the rear E-Locker worked!!! So, while I was searching this site, I found the write-up to make the E-Locker work in any mode. I then remembered that I had seen this before and had all the parts in stock, with an old write-up. I compared the 2 write-ups, and installed the relay this morning. Works like a charm, something I wanted to do for years just never did. I didn't install the diode yet as I just ordered a pack of 5 from ebay last night. When they get here, I will install the diode. Thanks again for all the help, JP.

 

Forgot to say that even the E-Locker light works!!! I verified proper operation by jacking up one rear tire, and with the truck in neutral, the wheel spun freely, I pushed the button and it locked, and the E-Locker light came on!!! ABS light also came on as well as VSC, correct??? I pushed the button again and the lights went off and the wheel spun freely again, success. Just one question, I assume the vehicle should be stopped to engage the rear E-Locker???

 

You have to be under 3mph before the ECU will shift it so yea basically you should be stopped or barely rolling especially when locking it.

 

Thanks for the quick response. Even with the relay, the ECU controls the locking of the rear diff??? Good to know. And glad to hear that I can't inadvertently hit the button and do damage???

 

No with the external relay you are bypassing the ECU's control of the locker, I was just saying if the ECU was in charge it won't allow engagement above 3 mph.

 

So, in your opinion what precautions should I take, as you know the rear diff lock button is right next to the fog light button. And what damage can be done if I accidentally hit it going 40 or 50 mph, in a straight line.

 

I mean you could put a switch somewhere inline to keep it disabled until you need it if it wouldn't inconvienence you, I've only ever been in a situation one time where I needed it but I still operate it from time to time to keep it working.
I also have a 2low module installed so I can use mine in 2low if I need to.

 

Thanks, that's certainly an option. But, do you know if I can do any damage if I accidently hit the switch while driving at speeds of 40 or 50 MPH, in a straight line??? If you don't think there will be any danger, I won't bother with the disable switch. I value your opinion.

 

Toyota engineering won’t allow you to do something stupid. If you press diff lock in 2hi at highway speed it will simply blink. You have to be basically stopped and also in 4LO for it to engage.

The owners manual is a great source of info. I have an off-road and there is also a door sticker and sun visor placard in case you’re confused.

 

Yes, thank you for the reply. And up until this morning that was the case, and I understood that. But, I just installed the relay mod that will allow the rear E-Locker to work in any mode. My question is; will I do damage if I hit the rear locker button in-advertently at speed???

 

Going in a straight line I wouldnt think so but I can't say for sure.

He did the locker anytime mod which basically bypasses the 4wd ECU and thus the safety limits.

 

I didn't it would do any damage provided I was going in a straight line, but was looking for some kind of confirmation that my theory is sound.