Tech Tip: Ford Pickup Upshifts Below 15 mph – UnderhoodService

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Technical resources to help diagnose and repair engine-related service issues.
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Tech Tip: Ford Pickup Upshifts Below 15 mph

A 1989-'95 Ford pickup equipped with four-wheel drive and a manually shifted transfer case may upshift to third gear under 15 mph while in two-wheel drive. This may be caused by a false four-low signal at the controller. With the transfer case in two-wheel drive and the engine running, check the voltage at controller pin 14 on 1994-'95 7.3L Turbo diesel models or pin 12 on all other models.

Underhood Service Staff Writers
By Underhood Service Staff Writers
Published:

Vehicles:
1989-’95 Ford pickup.

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Symptom:
A 1989-’95 Ford pickup equipped with four-wheel drive and a manually shifted transfer case may upshift to third gear under 15 mph while in two-wheel drive. This may be caused by a false four-low signal at the controller.

With the transfer case in two-wheel drive and the engine running, check the voltage at controller pin 14 on 1994-’95 7.3L Turbo diesel models or pin 12 on all other models.

If the voltage is zero, check for a faulty transfer case switch, or a damaged connector. Also check the operation of the dash bulb and the harness under the dash for a cut on the dash panel brace.

Note: An aluminum spacer washer must be installed between the switch and the case.

Technical service bulletin courtesy of ALLDATA.

For additional information, visit www.alldata.com.

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