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Old 02-13-2020, 06:15 PM
Clinticus Clinticus is offline
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Join Date: Feb 2020
Location: San Antonio, TX
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Quote:
Originally Posted by andrewwynn View Post
The shift to 4th is result not the cause.In other words, it's shifting into 4th because that what failsafe does.

Have you ever seen odd display of the selected gear in the dashboard? Eg in park, but no P, etc?

Often the cause of the failsafe is a dirty connector on the back of the transmission. It happened to me, and after I cleaned it, about 9 months later it happened again right after I got splashed with slush from a passing cat on the freeway. (I really need to seal that better; I think there's a design flaw that lets water come right through the center of the wire bundled).

Anyhow, on the 8 cyl I think the gear selector switch being external has a separate connector; either off those connectors get loose or dirty and it will give the exact symptoms you describe.

Voltage fluctuation from alternator will also kick the transmission into failsafe as well, and it can be just one momentary dip to cause it, so a real time reading with min/max voltage liked my fluke 87 will do is the best way to confirm or deny voltage dips
Thank you for your response and the information. I did clean all electrical contacts with electronic cleaner during both fluid change and wiring harness replacement. Will check alternator voltage. What is the recommended mix/max range?
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