1999 GMC Savana G 1500 passenger van
put 3 transmissions in and still getting P1840 code. Changed valve body and sensors.
Using dexron 6 transmision fluid
P1840 - Transmission Transfer Case Shift Motor Short Circuit To Battery Read more: http://engine-codes.com/p1840.html#ixzz3ae07ZuDs
Check for possible pinched wiring causing short/ also ohm read transfer case shift moter resistance. That value can be obtained by anyone who has transmission diagnostic software.
That code is not viable for your rig, you have no transfer case shift motor. Something else could be causing the erroneous code, as Tooloose stated check the wiring, a faulty sensor ground can cause all kinds of crazy codes.
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