need rr diff wire diagram. no life from actuator

whats up guys? i need a wire diagram for my 2004 v-6 auto trd's rr diff system. light just keeps flashing and theres no life from the actuator. checked the switches on the transfer case and rear diff, both are operating as should. while open the dmm shows ofl and while closed i got 0.1ohms. so id like to check to see if im getting power and signal to the rr diff actuator. thanks for any help.......

 

just the man i was hoping to hear from. perfect! thx chris. you are a true tw jedi master. ill test her out tomorow at work.

 

good to know. i will check it out if im getting power/signal back there. thanks again for the help!

 

first of all i wanna thank chris4x4 once again for coming through with the wiring diagram last night and making todays testing a breeze. now to the update, well things are not looking good after testing pin 3 at the actuator for a power signal, i found 0v. now knowing that is for sure a electrical problem i moved to the diff ecu. as expected i had power coming from the fuses into terminals 4 & 5. also verified the ecu's ground form terminal 8(grey wire). so then the bad news, nothing out of terminal 3 just like at the actuator. at this point im basicaly convenced its the ecu it self. got a freind at a local yota dealer looking in to it tonight, so fingers crossed.. if anyone sees something in the diagram above im missing please speak soon. thx for any help guys. chris are you out there? heeeeellp!

 

All right, let's see if we can get this figured out.

You said you had no power to the actuator, or power out of the ECU, right? Your light always flashes, and never goes solid. You have the transfer lever in 4Lo, and the 4WD light is on, too?

My next step would be to check the 4wd switch, that tells the ECU the truck is in 4Lo. If this is always showing to be in 2 or 4Hi, the diff lock will not engage.

The actuators rarely fail, and I don't recall replacing any ECU's either. As a matter of fact, I don't recall seeing any Taco's come in that the system didn't work on.

I'm guessing it's something simple, and it should be pretty easy to narrow it down.

 

all the above condition q's are correct. idling in 4lo with the button engaged. i did drive it in 4lo to confirm its operation so it for sure in 4lo and working. puts a on my face to hear you say youve never had an ecu go bad though! i did pull the switchs out and test them off the truck. they seem to be working with my meter showing ofl with the plunger/ball out, and the meter showing 0.1ohms with the switch closed(plunger/ball in). i tested both switchs this way. i assumed, hate that word, at that point they are working. just to make sure i will climb under and jump the harness to bypass the switch and see it the system engages. so im off to work boys hopefully i find time to try it today. thx for the help, ill report back.

 

well jumped the switch on the transfercase and still got no life back there. jumped the switch on the diff and as expected the light stop flashing but theres still no power to the actuator..ideas????

 

Kev covered the stuff i woulda asked...I'm outta this hunt all ready. Sorry amigo.

Best of luck!!

 

i didnt check the fuse. i guess i figured it was good since the 4wd is working. ill double check just to make sure though.

 

Look on page 2 of this troubleshooting PDF. It tells you how to isolate the ECU, and if it's bad. This is the exact same page out of our factory Toyota repair manuals, so with it, you should be able to figure out what's going on.

 

thx kev.

ill be back in the shop on tuesday and we'll get it figured out.

 

well i found the time to do the above diag and things are not looking good for the 4wd pcm. performed all the input test on page 2 of the above link from kev and found all input to be good. infact the only test that failed was the last one on the page, testing voltage between terminals m1 and m2 of ecu during switch operation. i got no changes in voltage at all, nor was there v's coming out of either terminal. so the last thing to do will be to pull the actuator out to service and bench test it to verifie its operation. i know i could just hook battery power up to it on the truck but im gonna take chris4x4's advice and clean it up real good. but if works which i think it will then ill need a known good pcm to install as seen in step (c,5). luckly i got friend at the local yota dealer that might be able to make that happen for me. wish me luck, my taco needs some

big thanks again to kev and chris for coming through with tech info needed for all these test. thanks boys!

 

What dealer are you taking it to? I used to work at Gresham Toyota, and was pretty good friends with a few guys at Broadway, and out at Royal Moore.

 

i wont be taking it to the dealer to get it fixed, just to borrow a 4wd ecu real quick. i work at honda & we have a partner toyota dealer in wilsonville. so ill probably just have to drive down on one of my days off. but thank you for the offer.