Electrical need starter second opinion

Discussion in 'Fox 5.0 Mustang Tech' started by 7991LXnSHO, Mar 15, 2013.


  1. 7991LXnSHO

    7991LXnSHO Well-Known Member

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    My starter started a new trick today. It hung up in the starting position twice today. I hit the key again and it disengaged. Shutting off the switch first did not stop the spinning, so I also suspect the solenoid. If I was able to right now, I would pull the starter and see if the Bendix was hanging up. If there was any question, I would bench test a new one at the store and put it on. If it was an older GM, I'd replace the dash mounted starting switch too. This is a little different cost and hassle wise. It has not been leaking oil to gum it up till recently, but there was a new puddle farther back on the cardboard this spring I need to look for the source. I replaced the battery and wall mount solenoid last fall as the battery was dying and did not pass the tester. As I will be having to pay to get it done if it involves under car work, what do you suggest? I can find jrichker's starting checklist if I need it. I also have pliers and a wrench for the battery cable nut handy. Thanks for sharing your Mustang experience and help!
     
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  2. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Save yourself the trouble of doing a search...

    No Crank checklist for 5.0 Mustangs

    Revised 05-Oct-2010 to update Fluke references.

    No crank, slow crank and stuck starter solenoid problems have the same root causes – low battery voltage and poor connections. For that reason, they are grouped together.
    Use the same initial group of tests to find the root cause of both no crank and stuck solenoid problems.

    Since some of the tests will bypass the safety interlocks, make sure that the car is in neutral and the parking brake is set. Becoming a pancake isn’t part of the repair process…


    1.) Will the car start if it is jumped? Then clean battery terminals and check battery for low charge and dead cells. A good battery will measure 12-13 volts at full charge with the ignition switch in the Run position but without the engine running.
    A voltmeter placed across the battery terminals should show a minimum of 9.5-10 volts when the ignition switch is turned to the Start position and the starter engages or tries to engage. Less than this will result in a clicking solenoid, or slow cranking (if it cranks at all) or a starter solenoid that sticks and welds the contacts together.

    Most auto parts stores will check your battery for free. It does not have to be installed in the car to have it checked; you can carry it with you to the auto parts store.

    The battery posts and inside of the battery post terminals should be scraped clean with a knife or battery post cleaner tool. This little trick will fix a surprising number of no start problems.

    The clamp on with 2 bolts battery terminal ends are a known problem causer. Any place you see green on a copper wire is corrosion. Corrosion gets in the clamped joint and works its way up the wire under the insulation. Corroded connections do not conduct electricity well. Avoid them like the plague...

    If the starter solenoid welds the contacts, then the starter will attempt to run anytime there is power in the battery. The cables and solenoid will get very hot, and may even start smoking. The temporary fix for a welded starter solenoid is to disconnect the battery and smack the back of the solenoid housing a sharp blow with a hammer. This may cause the contacts to unstick and work normally for a while.

    A voltmeter is handy if you are familiar with how to use it to find bad connections. Measure the voltage drop across a connection while trying to start the car: more than .5 volts across a connection indicates a problem. The voltage drop tests need to be done while cranking the engine. It's the current flowing through a connection or wire that causes the voltage drop.

    See http://assets.fluke.com/appnotes/automotive/beatbook.pdf for help for help troubleshooting voltage drops across connections and components. .

    [​IMG]

    2.) Check the battery to engine block ground down near the oil filter, and the ground behind the engine to the firewall. All grounds should be clean and shiny. Use some sandpaper to clean them up.

    3.) Jump the big terminals on the starter solenoid next to the battery with a screwdriver - watch out for the sparks! If the engine cranks, the starter and power wiring is good. The starter relay is also known as a starter solenoid.

    The rest of the tech note only concerns no crank problems. If your problem was a stuck solenoid, go back to step 1.

    4.) Then pull the small push on connector (small red/blue wire) off the starter solenoid (Looks like it is stuck on a screw). Then jump between the screw and the terminal that is connected to the battery. If it cranks, the relay is good and your problem is in the rest of the circuit.

    5.) Remember to check the ignition switch, neutral safety switch on auto trans and the clutch safety switch on manual trans cars. If they are good, then you have wiring problems.

    Typical start circuit...
    Diagram courtesy of Tmoss & Stang&2birds
    [​IMG]


    6.) Pull the starter and take it to AutoZone or Pep Boys and have them test it. Starter fails test, then replace it. If you got this far, the starter is probably bad.


    Starter solenoid wiring for 86-91 Mustang
    [​IMG]


    Starter solenoid wiring 92-93 Mustang or earlier Mustang with upgraded high torque mini starter.
    [​IMG]

    Electrical checks for the switches and starter solenoid

    Remove the small red/blue wire from the starter solenoid. Use a screwdriver to bridge the connection from the battery positive connection on the starter solenoid to the small screw where the red/blue wire was connected. The starter should crank the engine. If it does not, the starter solenoid is defective or the battery lacks sufficient charge to crank the engine.

    If the starter does crank the engine, the problem is in the clutch safety circuit (5 speed) or Neutral Sense Switch (auto trans) or ignition switch.


    See the Typical start circuit diagram above for wiring information for troubleshooting.

    You will need a voltmeter or test lamp for the rest of the checks. Connect one lead of the voltmeter or test lamp to ground. The other lead will connect to the item under test.
    Look for 12 volts on the white/pink wire when the ignition switch is turned to the Start position. Check the ignition switch first.
    No 12 volts, replace the ignition switch.

    The next step will require you to push the clutch pedal to the floor (5 speed) or put the transmission in neutral (auto trans) while the ignition switch is turned to the Start position.
    Good 12 volts, check the clutch safety switch (5 speed) or Neutral Sense Switch (auto trans) for good 12 volts on both sides of the switches. No 12 volts on both sides of the switch and the switches are defective or out of adjustment. Check the wiring for bad connections while you are at it.
     
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  3. 7991LXnSHO

    7991LXnSHO Well-Known Member

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    I will check the grounds and the wiring for voltage drops Saturday. I have plenty of volts, the connections are clean, and jumping the solenoid works. The rest of the list I mostly had figured out and done. But as this is an intermittent problem, I still am wondering which part is the most likely culprit. If the wires check out, is it the solenoid/relay since it keeps going with the ignition switch off? Or is the ignition switch the more likely problem on a 1991? I hope it is the cheap one.
     
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  4. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    I would try the ignition switch first.


    Some of the symptoms of ignition switch problems are things that don’t work or are intermittent like radio, turn signals, wipers or heater.

    There was a FREE recall on Ford ignition switches. They overheat and sometimes catch fire. That burns up the steering column and sometimes the car interior. Since this is very old information, you may not be able to get the switch replaced for free anymore. The auto parts stores sell the switches for $13-$15.

    [​IMG]

    [​IMG]

    [​IMG]

    Saleen0679 was nice enough to dig this up for us awhile back: Replace a 1979-1993 Ignition Switch Assembly
     
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  5. ratio411

    ratio411 Founding Member

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    Usually starter hang up caused by a sticking solenoid.
    If the ignition switch was sticking, it would have to be more than intermittent, because the rod from the key to the switch is a solid link, and when the key moves, it moves, therefore if it was broken, it would be all the time. The solenoid works on an electromagnet, and can fail one time, and work the next time. It's not like a solid metal link that is either broken or not broken. Make sense?

    It can't be your Bendix either.
    If the Bendix sticks, yes, you will hear the engine rolling over the starter, or grinding against it, but you won't have the starter motor actually energized and running.
     
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  6. 7991LXnSHO

    7991LXnSHO Well-Known Member

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    Thanks for the info and second opinion guesses. I had not looked up the ignition switch price, but I figured it was as expensive as the multifunction turn signal switch. After the wires are checked, I can warranty the relay and replace the switch then be ready.
     
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  7. 7991LXnSHO

    7991LXnSHO Well-Known Member

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    You want to know how these things turn out and rarely find out. I had not gotten the new switches in when it did it again. I let the clutch out in neutral - it kept going. The ignition switch position made no difference. I pulled the starter signal wire from the solenoid and it kept going. I tapped the solenoid with a hammer and it finally disengaged the starter. So I warranteed the fender mounted solenoid and hope it is done acting up.

    I still need to get the vin and check if Ford replaced the ignition switch. Somehow I missed out on the other recalls like the cruise control one on other Fords, (no options except ac and carpet on that one,) but this sounds too serious to mess with.
     
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