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1993 Ford F-150 Repair Question


Topics covered: Trailer, Wiring, Abs.
Mileage: 77,000 miles.

Asked on October 7, 2011

Cruise speed surges

When set the cruise control the speed surges up and down. I have replaced speed sensor in rear end & checked the ring in the rearened. The speedometer has been replaced and no change. I unplugged the controller behind the glovebox and the cruise works fine. However my ford dealer mechanic says it's no guarantee that is the problem. Also I have replaced vaccine lines under the hood. Please help, Thank You.

Bob m
Avatar Asked by bmiller3316

Answer

Replied on October 7, 2011

check your throttle linkage and cruise cable for binding, if that isn't doing that it may be your servo going bad.

Tiny Answered by hmac300 (expert)
17,813 answers provided
Replied on October 7, 2011

Thanks for the info. I checked the linkage and it is not binding. I can't figure why it works fine with the abs controller unplugged. Driving me crazy! Thanks for any & all help.
Bob

Tiny Response from bmiller3316
1 question asked
Replied on October 7, 2011

had you said something earlier about eh abs you might get a better response. the abs has the cruise control connected directly to it. as you apply the brakes it kills the cruise. so it's eiteh rgot a short in it or one of the wires are touching where they aren't supposed to an dkilling the cruise. it also connects to the trailerbrake if you have one as well as the speed sensor to the rear. if any of htosea re screwing up or the abs unit itself then your cruise isn't going to work right. nexttiem give ALL the information you can, engine/trans 4wd or not as well as a complete detail of what is going on.

Tiny Answered by hmac300 (expert)
17,813 answers provided

Replied on October 7, 2011

This makes so much sense, I'll check this wiring. I do have trailerbrakes also. Truck is a 93 f150 with a 351w which has the upgrade to the lighting mass air flow kit from ford. Thanks for so much

Tiny Response from bmiller3316
1 question asked
Replied on October 9, 2011

He is correct. Check the wiring (especially the trailer wiring) for damage. There also is a plug at the rear of the vehicle for the wiring to the trailer. Check it for damage.

Tiny Answered by Jacobandnickolas (expert)
57,318 answers provided
Replied on October 9, 2011

Thanks

Going for test drive Sunday.

Tiny Response from bmiller3316
1 question asked

Replied on October 9, 2011

Let us know what you find.

Tiny Answered by Jacobandnickolas (expert)
57,318 answers provided
Replied on October 9, 2011

I sure will. I have completely unhooked all the trailer brake wiring. Thanks

Tiny Response from bmiller3316
1 question asked
Replied on October 9, 2011

Thanks

Tiny Answered by Jacobandnickolas (expert)
57,318 answers provided
Replied on October 10, 2011

Well it looks like the trailer brake controller is causing the up & down when on cruise. The wiring harness checks out fine also. Thanks for all the help.

Tiny Response from bmiller3316
1 question asked