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I found my 97 manual transmission rav's center differential lock wasn't working, did the test with it raised, e brake and lock engaged, the engine kept running, just front wheel turning..So, I began trying to diagnose the cause, checking vacuum and e-switches... the light was coming on, but no warning buzzer/beeper...So I ran some compressor air down the vacuum lines, swapped around hoses, checking switches, etc... Now...for some unknown reason, the center differential lock is engaged but turning it off at the dash makes the beeper go and it's now staying locked... I took it off the stands and ran around in my yard, snow covered, and it's definitely spinning front and rear wheels. It also kills the motor with the e brake on and all 4 wheels lifted... doesn't matter what the dash switch says, other than it beeps a warning all the time now when the light is out..stops when the center differential lock switch is "on"
.. anyone got any hints? I did order a new vacuum switch valve, but the old ones "seem" to be functional..not 100% sure, that's why I have another coming... Sheesh,.
Oh yeah, it made a continuous unmesh/gear kinda sound when I had it up and the wheels turning...no noises when spinning donuts in the snow..馃榿
 

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Thanks, I've read that post and most everything else I can find. I DID try reverse when lifted and I tried backing up with the locking switch off...
The dash sends current to both vacuum switches...one when "on" and to the other vacuum valve when "off". Is that right?
Also, when I had the wheels up and the car in gear, testing, that mechanical miss-meshed sort of sound was unchanging regardless of where the switch was or 2nd vs reverse gear...but that sound was gone when I tested on the snowy field outside...the beeper was sounding whenever I turned off the CDS (dash switch) and that consistently stopped when the instrument panel indicator was was switched "on"...
I'm thinking I may have engaged the lock somehow when blowing air thru the vacuum hoses and now it's stuck "on".. somehow.. Can that actuator be reached by a human hand?
I can tell the previous owner messed around with this...one of the switches came from Amazon, I think...and one hose has a hose clamp at the vacuum valve...help! I'm in over my head now..馃槡 Don Hanson I hi
 

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Check this post by eodgator which has a picture of the correct diagram for the vacuum lines along with the diff lock system inspection pdf from the factory service manual:
https://www.rav4world.com/threads/diff-lock-not-functioning.207577/post-2640899

EDIT: Apparently the attachment doesn't work anymore, so go here:
https://cardiagn.com/manual-transaxle-1996-rav4/ (pages 72-76)
https://cardiagn.com/center-differential-lock-96-99-rav4/ and here:
https://cardiagn.com/center-differential-lock-wiring-diagrams-96-99-rav4/
 

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Discussion Starter #5
Check this post by eodgator which has a picture of the correct diagram for the vacuum lines along with the diff lock system inspection pdf from the factory service manual:
https://www.rav4world.com/threads/diff-lock-not-functioning.207577/post-2640899

EDIT: Apparently the attachment doesn't work anymore, so go here:
https://cardiagn.com/manual-transaxle-1996-rav4/ (pages 72-76)
https://cardiagn.com/center-differential-lock-96-99-rav4/ and here:
https://cardiagn.com/center-differential-lock-wiring-diagrams-96-99-rav4/
Thanks, with all this I should be able to get it done.
 

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I have a problem where when I disengage the lock (pressing the switch on the dash) the warning horn doesn't go off for five miles or so. I wonder if this may be caused by a vacuum leak somewhere, or if there's a timer on the horn and my differential is actually still locked?
 
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