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1998 5dr manual transmission. Center diff lock has never worked. When purchased the "C. Diff Lock" light was *always* ON but it was clear by the way the vehicle was driving that it wasn't actually engaged.

The dealership made it so the light isn't on anymore but said to actually fix the problem would be $600~800.

I settled for not having a locker.

I've done a few clutch jobs and am fairly handy. I have a feeling a quicky clutch job is what caused this problem in the first place. I'm about to change the front CV shafts and figured "while I'm in there..."

My Chilton manual doesn't touch much of anything with the 4wd system. Does anyone have an idea of what the problem is and what it would take to fix it? Is there a more in depth manual out there somewhere?

Thanks for any pointers.

-Rob
 

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I will give it a 99.9 per cent chance that the vacuum lines going from the intake manifold and VSV, down to the actuator are either cracked and broken, or have fallen off, or were taken off during repairs intentionally or by accident, and never put back.

I'll give it a .1 per cent chance that there is actually anything wrong with the diff lock, or the actuator.

Oil leaking from around the back of the valve cover runs down these lines, and at the bottom it eats away at the rubber, weakening it, and thereby causing them to become disconnected from the actuator. I've seen many rav4's where there is a huge vacuum leak, and the owner didnt even know what the diff lock does.
 

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When I got my Rav the switch turned the light on and off but the warning buzzer never sounded.
Test proved it did not lock. Turned out that one of the wires was bad right at the solenoid.
Works great now and always unlocks easily with just a short beep.

Took my Rav out with the local 4x4 club a couple of times and needed the locking feature.
It is a nice feature and a lot of fun!
 

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Hi All,

Iam a newbie here. Mine is 1999 Rav4 Manual Tranny 5spd. The diff lock button turns the light on but does not actually engage the center diff lock. What annoys me is the warning buzzer gives 3 to 4 beeps after i turn off the center diff lock and then turns off. Any one willing to help me out here. By the way when i bought my rav, all hoses were disconnected from the vacuum actuator valve and i just figured out by means of guess line as to where they will connect. I may have connected them wrongly since when I was figuring out which one goes where, i accidentally got to turn on the c diff in Lock position which only freed up after swapping hoses from the vacuum actuator...help please
 

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What annoys me is the warning buzzer gives 3 to 4 beeps after i turn off the center diff lock and then turns off.
That's normal. Mine sometimes only gives one beep, but usually I get 3 or 4.

By the way when i bought my rav, all hoses were disconnected from the vacuum actuator valve and i just figured out by means of guess line as to where they will connect. I may have connected them wrongly since when I was figuring out which one goes where, i accidentally got to turn on the c diff in Lock position which only freed up after swapping hoses from the vacuum actuator...help please
Check these posts for vacuum line diagrams and troubleshooting guides:
https://www.rav4world.com/forums/85...lp-needed-center-differential.html#post940982
https://www.rav4world.com/forums/85...d-sourcing-motor-mount-bolts.html#post2164961

EDIT: Inaccurate diagram removed. Correct one posted by eodgator in a following post.
 

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'99 RAV4.1, 3MZ-FE, E250F 4x4, Torsen Dif
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I made the color diagram but I'm pretty sure I made a mistake on it, sorry about that, it's hard to see in that area. I deleted it from my threads until I have a chance to check it out. I just got a USB Endoscope to use with my phone, I'll try to get in there for some photos.

Unfortunately I cannot find how these connect to the actuator.
 

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I made the color diagram but I'm pretty sure I made a mistake on it, sorry about that, it's hard to see in that area. I deleted it from my threads until I have a chance to check it out. I just got a USB Endoscope to use with my phone, I'll try to get in there for some photos.

Unfortunately I cannot find how these connect to the actuator.
Hi There,

That would be much appreciated.
 

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'99 RAV4.1, 3MZ-FE, E250F 4x4, Torsen Dif
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I made the color diagram but I'm pretty sure I made a mistake on it, sorry about that, it's hard to see in that area. I deleted it from my threads until I have a chance to check it out.
My apologies for that. I probably shouldn't have re-uploaded it without asking your permission in the first place.
 

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'99 RAV4.1, 3MZ-FE, E250F 4x4, Torsen Dif
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My apologies for that. I probably shouldn't have re-uploaded it without asking your permission in the first place.
No problem about it, I actually got the original hand drawn i had posted and that you reposted from a Toyota Dealership, when I tried hooking mine up that way it didn't work.
 

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'99 RAV4.1, 3MZ-FE, E250F 4x4, Torsen Dif
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Here's my logic on the new diagram.

In the below illustration it shows vacuum lines "0" and "2" location on the VSVs, that was key because two of the vacuum ports on the transfer actuator are labeled "0" and "2" the other ports are unlabeled. The unlabeled port next to "2" on the transfer actuator is a smaller diameter than the others and that matches the size coming from the intake manifold. The split line that goes to ports "1" and "3" on the VSVs is left going to the lone port on the secondary vacuum chamber.

I just confirmed that this works



 

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Hi Eodgator,

Much thanks for the reply. Sorry for a late thank you. Finally some how i Managed to get all those hoses lined up. 1 of those hoses (Green in your color diagram) had a rather tricky crack which only was visible when i took the entire hose outside.

But now when i Turn on Diff lock, the light on Dash goes on. The diff lock does not actuate but as soon as I turn on the C Diff Lock I hear the engine getting rough Idle , I suspect Vacuum Leak. I Probably will have to carefully examine my hoses.

The funny thing was that despite C Diff not being locked, it still beeps 3 to 4 times when I Turn off.

Will give more tries and update you guys as soon as I get time to get off my work desk and get dirty.

Cheers my new Ravy Mates.
 

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'99 RAV4.1, 3MZ-FE, E250F 4x4, Torsen Dif
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I know it's difficult to get to the actuator so a made a step by step guide how I did it. If one vacuum hose is compromised they all are or soon will be. Replace them all or you will constantly be having these issues. See my thread at https://www.rav4world.com/forums/94...ine-replacement-high-temp-silicone-lines.html. Just go by size rather than color. Initially I only color coded by size but later I switched the ones for the differential actuator to be by location. The colors are only a recommendation to make it easier to trace the lines in particular the ones going to the actuator.


A guide for the easier way to do get to get to the vacuum actuator to install the vacuum lines.

Materials needed (you can use different colored lines, these are just suggestions)(I got the colors and great quality hoses from ebay.com):
2 ft - 5mm black silicone high temp vacuum line
2 ft - 5mm green silicone high temp vacuum line
2 ft - 5mm blue silicone high temp vacuum line
2 ft - 3mm red silicone high temp vacuum line
Reuse the vacuum line splitter and anti-chafe tubing

Tools needed:
- long reach needle nose pliers
- jack
- jack stand

Procedure:
- Jack the passenger side up at the "frame" just behind the engine to lift the tire off the ground and place a jack stand under the car for safety. Set the brake, chock the rear tires. The reason you jack it up is to make it easier to work under the car and to drop the tie rod down so you can get your arm in there.
- Assemble your vacuum lines using the anti chafe material provided or replace with new material, remember it gets really hot here so if you are replacing it use something heat resistant.
- Lower the assembled hoses behind the engine roughly into place.
- Install the blue line (#3) first, this is the most difficult and you are probably not going to do it if you have large arms and fingers. The location is under the black (#0) vacuum line, you cannot see it you have to feel for it, you will feel one of the mounting bolts move your hand around until you feel the vacuum port. Grab the hose between two fingers like holding a cigarette and push it on, it is not an easy job and it can be frustrating but it is doable.
- Using long reach needle nose pliers put the other hoses on starting at the 3mm hose
- Once the lower hoses are on, connect them to the appropriate locations on the VSVs according to the diagram
 

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Hi All,

Much thanks for your replies, help and solutions. Just out of luck I had a friend with same 1999 Rav4 so i just tried to swap the VSVs from him to check. It Worked! So i went to the parts shop and got two new VSV and now its working perfectly.

I might soon need to change those Vacuum hoses as stated by eodgator as it has already 180k miles on it and being in harsh tropic.

But for now its working fine.
 
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