Just a guess ......
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If the sensors are the same or similar to the ones used on Ford Explorers, I would agree with your dealer.
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(be prepared for a number of 'I believe' statements) .....
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I have never looked at the VX or Explorer transfer case, but 'I believe' they are similar: Borg Warner manufacturers the transfer case for both vehicles.
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'I believe' the Explorer transfer case utilizes 'Hall' (motion ? magnetic ? electro-magnetic ? ) sensors that expire often - and require replacement. The VX may also fit into this category.
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t2p