More 4WD issues

Problem with that if a electrical/electronic issue it isn't by the powertrain warranty.

 

So after a month or so of using a 9v battery to connect to the TC actuator on the rare instances I needed 4 lo...I was out, waaay out on a trail with some buddies this week. All was good going along in 4 hi when all of a sudden I got a grinding noise from below. Stopped the truck, checked underneath. Nothing obvious. Switched from 4hi to 2 wd, no problems, switched back into 4 hi no problem continued on the trail. Had to get 4lo to navigate a section, switched in fine, couldn't switch out (the same issue). After the day was over, tried my battery in the TC actuator, couldn't get it to shift. Stuck in 4 lo.

Got home, at 230 am after driving back the LONG way in 4 lo at about 20mph.

Went out today to check. Tried the battery (putting 9v to pin 1&2 on TC actuator) wouldn't shift. Had to loosen the cover a little, then it worked. Tried to shift between all modes, and now anything 4wd gives a heavy high pitched grind from the TC and then it shifts. Parked it in 2wd. Off to the dealer Monday for diagnosis.

 

Just got diagnosis from the dealer. They are saying they need to replace the 4wd ECU. Parts and labor going to be @500 bucks. I'll get more details when I pick it up later today to wait for the part to arrive. Hopefully this fixes the problem. Sucks but better than a new transfer case.

 

You ever replace the 4wd switch?
The P279E points VERY strongly at that switch or the harness attaching it to the ECU...
While its possible its the ECU, I would put it as pretty unlikely.

 

I didn't replace the switch but I did take it apart, checked the harness and wires, cleaned it, reinstall. Didn't help. The dealer allegedly diagnosed the existing ECU as bad, not sure exactly what was bad, but the SA said they checked voltages. They attached another ECU and the system functioned properly. Again, allegedly. Will see in a couple days when the part arrives.

 

So the dealer has had my truck since Monday, attempting to "program" the 4wd ECU. I was unaware these needed programming. They are now telling me the new ECU won't function because the transfer case actuator is damaged. Waiting on answers from them as to what exactly in the TC actuator is damaged.

Advice? Any questions I should ask? I'm rapidly getting out of my depth the more technical this becomes.

 

Sounds like they miss diagnosed the issue and it was the actuator all along.

 

Just spoke to the SM. He swears on a stack of Bibles the ECU was bad....of course. He is saying the shift rod on the TC actuator is chewed up. Believable based on the failure and noises I had on the trail. (Never told him that) Strange progression of symptoms though.

 

Highly unlikely.

 

I believe Toyota is also unaware the 4wd ECU requires programming.... I never saw that for the 4wd ECU in repair manual (it is true for main body ecu https://www.tacomaworld.com/threads...n-body-ecu-installation.756090/#post-26946924 )

(So yeah, not ECU but probably an actuator from day1)

 

Just got a call from the SM at the dealer. Asked about the possibility of replacing the TC actuator and putting the original 4wd ECU back to see if there was in fact a misdiagnosis. He won't do that. After a bit of negotiations, he offered a 25% discount on the TC actuator and to cover the labor for the install. Not sure I can do better. I did tell him to give me back the parts they take off. The deal he offered basically covers, plus a few bucks, what they charged for the ECU swap.

 

Yeah, but if electronic, or electrical your sol.

 

I’d let him know you’ll pay for the fix and expect any misdiagnosed P/L to be removed. Any redneck can play swap-a-part in their driveway,,,, in my mind, the reason I take it to the shop is to be properly diagnosed and repaired without adding more time and money guessing and part swapping.

 

Yup. Even if OP got the old (still functioning) 4x4 module back, he probably wouldnt be able to sell it cause they dont seem to go bad.

 

I hear ya man... here's your acknowledgement since you felt the need to let me know on two different occasions now, 2 months apart.

 

I really dont know what to suggest with them having you bent over at this point...
There is microscopic chance it was ever the 4wd ECU... I mean it might have been hit by lightning.... or a rat peed on just that but nothing else?

There is a decent chance it is either actuator. There is a small chance it is the wiring to either actuator damaged.

If it were I, I would get it out of there and work on it myself, and no I am not some super-competent mechanic or anything... but I am willing to mess something up 'learning'. If somebody is going to do a crappy repair, it might as well be me, they have proven them selves to be no-better than any of us.

With an ohmmeter or techstream you can diagnose the issue yourself without them. And replacing either actuator is pretty easy. You can also replace the transfer case actuator if the shift rod is ok, you just need to re-time the actuator at install ... Good Luck... let us know what happens
(https://youtu.be/GCY2BCdlU4I)

 

True. If the new TC actuator solves my issue, with the consideration they are giving me I'm not out any money, just time. And aggravation.

 

They are saying the shift rod is jacked. Not sure how.

 

Only thing I can think of is something is mis-aligned inside the t-case? Ive never split one of these cases open though so I dont have any first hand experience with that myself.

 

Same here... I just dont trust them after they pointed their finger at ECU.

But PLEASE let us know how it goes, and the final result. I know I learn something every time.
If nothing else, i would love to slap that removed 4wd ecu in my truck and test it out to see if it works....