Question about 1986 Ford F150 SuperCab

1 Answer

86 F150 Replacement Alternator not working!!!

The alternator in the truck was giving me problems (gauge needle was bouncing back and forth, headlights were dimming/flashing, checking with voltmeter showed an inconsistent flow of power would spike to 14 then down to 11 then back to 14. I took the alternator to Auto Zone and they tested it and said it was bad. I purchased and installed a new alternator but when I checked it with a voltmeter it did not appear to be charging. I took the alternator back and had it tested and it passed. I was told to replace one of the plugs (3 wire plug that goes to the stator) I replaced the plug but still no output. I have since noticed that there is a wire broken off near the fender well, I traced that wire back to it's source and it goes to the 3 wire plug I replaced. I don't believe this wire is the reason for the lack of output on the alternator because it looks like it's been broken off for some time. Any ideas on what this problem could be? Thank you in advance for any help you may be able to provide.

Posted by on

  • pbrjunkie Feb 23, 2009

    I have already replaced the belt with a new one. The battery is clean and the wires all appear to be in good shape with the exception of the one mentioned earlier.



1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.

    Brigadier General:

    An expert that has over 10,000 points.

  • Master
  • 3,533 Answers

I would check the drive belt and make sure all of the wires to the alternator and the battery are clean if the drive belt looks crank or worn replace it

Posted on Feb 23, 2009


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya Mechanic can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repair professionals here in the US.
click here to Talk to a Mechanic (only for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

When i start and run my 1983 ford truck the lights surge like flashing, the more gas i give the brighter it gets but it still surges. Also the voltmeter gauge bounces back and forth

it needs a new alternator its going out on you or maybe a loose wire on the alternator check the wires and at autozone for free they will test the alternator before replacing it

Sep 24, 2010 | Ford F-150 Cars & Trucks

1 Answer

1993 Dodge Spirit V6 Short?

Sounds like an alternator problem. Check belt to make sure it's tight, then have alternator tested.

Jan 06, 2010 | 1993 Dodge Spirit

2 Answers

Occassionally my dash gauges and radio will loose power while my red battery indicating light will come. My dash lighting stays on. Also, if my headlights are on they will flicker from normal to brighter...

yes, your problem remains in the alternator, also known as the generator wich alternates current to charge your batterry while accessories are on, eg, lights cd player and so forth, maybe a diode is losing the capability to handle the load, i recommend replacing the alternator or alternatively re-condition it. but that is most definately your problem.

Dec 04, 2009 | 2005 Ford Explorer Sport Trac

2 Answers

Charging gauge bouncing back and forth starts after jump

sounds like a shorted field in the alternator

Nov 07, 2009 | 1981 Ford F 150

1 Answer

Oldsmobile intrigue electrical problems

Probably your ignition switch needs changing. Check out the threads at

Jun 01, 2009 | 1999 Oldsmobile Intrigue

1 Answer

Alternator jumps up and down

Have alternator bench tested, could be the alt., test to confirm. Issue could also be bad wiring or faulty gauge cluster.

Mar 09, 2009 | 1997 GMC Safari

1 Answer

Headlights/ dash lights flashing

It sounds like a faulty voltage regulator, faulty alternator, or a bad ground. Try checking the voltage output with a voltmeter, preferably an analog (needle) type. If the needle is "bouncing" then the output of the alternator is not "steady". This voltage variation, if severe enough, could cause your electronic meters (such as your speedometer) to perform erratically.

Also, if you have performed any aftermarket modifications to the electrical system (such as high power stereo installs, etc), temporarily disconnect these and see if the problem resolves. A stock alternator for this car only puts out around 70-80 amps. It doesn't leave much of a margin for additional current draw from high power add-ons.

Nov 15, 2008 | 1997 Honda Civic

Not finding what you are looking for?
Cars & Trucks Logo

78 people viewed this question

Ask a Question

Usually answered in minutes!

Top Ford Experts


Level 3 Expert

77499 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22306 Answers


Level 3 Expert

5626 Answers

Are you a Ford Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides