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4x4 not engaging! Ideas?

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Old Jul 27, 2022 | 05:54 PM
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Mitchlvk's Avatar
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4x4 not engaging! Ideas?

I have a 94 runner head gasket blew so it sat for about 7 months. Had someone do a 3.4 swap and manual swap for me.. but now the 4x4 isn't working he said he did everything right and intrust him because it runs great. I heard if they a for a while the Little actuator will kind of seize up so you have to take the case off and slide by hand with something. Let me know what ya think
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Old Jul 27, 2022 | 07:38 PM
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millball's Avatar
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Probably a failure of ADD (automatic differential disconnect) somewhere or other.

A switch on the transfer case should make ground when you shift the transfer case into 4X4 and that tells a VSV (Vacuum switching valve)

to send vacuum to the ADD actuator. When the ADD shift fork is physically locked up, a switch lights the 4WD light in the dash cluster.

You still got the solid steel drive flanges and not manual hubs installed????
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Old Jul 27, 2022 | 07:51 PM
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Start with the easy stuff. Here's the FSM section on diagnosing. http://web.archive.org/web/201204242...26addcontr.pdf Toyota has you checking the VSVs first. Once you confirm all of that is working, you can move on to applying vacuum to the actuator.

My guess is that a vacuum line was left unconnected somewhere, and following the manual will tell you where.
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Old Jul 28, 2022 | 03:53 AM
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[QUOTE=millball;52478513]Probably a failure of ADD (automatic differential disconnect) somewhere or other.

A switch on the transfer case should make ground when you shift the transfer case into 4X4 and that tells a VSV (Vacuum switching valve)

to send vacuum to the ADD actuator. When the ADD shift fork is physically locked up, a switch lights the 4WD light in the dash cluster.

You still got the solid steel drive flanges and not manual hubs

I did not switch to manual hubs
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