77 f150 automatic 6cylinder 300 engine is it normal for the truck to run in one gear?

Asked by Jul 04, 2013 at 08:58 AM

Question type: Maintenance & Repair

My truck seems to stay
in one gear when I'm
driving it is this normal ?
I know for my car that's
of course newer 03 it's
automatic and u can see
that when it reaches a
point it changes gears
on it's own. On the truck
I keep my foot press in
the pedal and it keeps
going almost 65 or more
and it never changes

7 Answers


You may have a defective Modulator Valve on the tranny.

2 out of 2 people think this is helpful.

I would not drive the truck until you resolve the shifting problem as you are probably red lining the RPM and may blow the engine. Check the modulator valve on the tranny. They are fairly easy to change out.

2 out of 2 people think this is helpful.

Allen is right.. the answer is no it's not normal

1 out of 1 people think this is helpful.

Check your transmission fluid level. If that's ok then check for a broken or disconnected vacuum line going to the vacuum modulator on the transmission. This vacuum line will go from the intake manifold to a "gizmo" on the side of the transmission. HTH. -Jim

1 out of 1 people think this is helpful.

Where is the modulator valve located ? And the vacuum modulator ? Are they inside the transmission area ?

If they are inside the transmission is this possible to change while under truck there's good room is this ok or would it be difficult.

Tracy Hooks

Have you tried shifting it manually? Start out (easy) in 1, shift to 2 and then to D. The vacuum modulator is usually a small cylindrical object on the back of the trans just above the pan with a vacuum line attached. Check the kick-down rod's activation and travel too. The combination of these two controls (along with an internal governor) determine your shift points depending upon load, speed, and demand. Check the alignment of your gear selector too. A personal practice: never trust an old Ford in Park - always set the E-brake.

1 out of 1 people think this is helpful.

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