Relocating My Battery.... Solenoid Just Clicking?

Discussion in 'Fox 5.0 Mustang Tech' started by sen2two, Jan 3, 2014.

  1. I just finished up relocating my battery to the trunk and when I crank the car, the only thing that happens is a vibrating noise. Kind of like a dead or dying battery and the solenoid is just clicking really fast. I believe it is coming from the starter solenoid since I moved it to the back as well. I know its not my battery since I charged it completly full and tried again to get the same result.
    All I did was mount the battery and starter solenoid in the rear of the car. Then run the same wires that were connected to it to the trunk. Basically just made the wires longer.
    The only thing I can come up with is a bad ground....?

    here is a pic of the starter solenoid as it sits right now:
    All the wires on the left are connected to the wires they were orignally connected to in the engine bay. All I did was lengthen them. The single wire on the small post was also just lengthened.
    The large red wire on the same post as the bundle of wires is connected directly to the positive terminal on the battery.
    The large wire on the right is connected directly to the negative terminal on the battery. The battery is ground to one of the bolts that are holding down the battery box.
    The large wire that comes strait off the starter is connected directly to the negative terminal on the battery.
  2. might be a good idea to run a 10ga or so wire from the mounting screws to the same ground as your battery
  3. It's probably a connection issue.

    Ground it to the quad shock bracket bolt after removing it, then cleaning the paint off it then reinstalling.

    Your splicing skills could probably use some work, no reason reason any of those connections should require multiple inches worth of electrical tape.

    I don't like cheap crimps on battery cables, i like the ones that take a crimper (not just a pair of pliers with a notch) and then heat shrinks.
  4. all of these will get heat shrinked and wrapped in those wire loom covers. And i do tend to go a little crazy with the electrical tape, lol. I was just trying it out before I hid eveything away. I am hoping I just have a bad ground somewhere...
  5. I just tried adding another ground from the battery to a spot I sanded on the body in the trunk. And also added a ground from the starter solenoid to that same spot. Same thing...

    The solenoid is obviosly getting power if it's clicking. So which wires activate the starter? I think maybe whichever wire that are suppsoed to activate the starter, may have a bad connection.
  6. Do you have it grounded to the frame?

  7. No, just a sanded a spot to bare metal in the back trunk floor.
  8. ummm.... Is the big black wire coming from the starter supposed to be connected to my battery negative or the solenoid?

    I currently have it to the battery, and I am thinking it is suppsoed to be connected to the solenoid?
  9. I'm first going to assume that you still have the factory starter and your car is a 91 or older. The black 4 gauge wire on the right side of the solenoid should go directly to the starter. If the wire from your starter is connected to the battery ground and the wire from the solenoid is also grounded, you are effectively creating a dead short through the starter back to the battery. The starter only gets 12V. It's grounded through the bellhousing to the engine block.


    Thank jrichker for the diagram.

    Also, relocating that solenoid to the rear is not a greatest idea. I'm sure you did it so you didn't have to spend a ton of money on proper sized battery cables to run to the front of the car. However, a #4 wire from the trunk to the starter is going to result in slow cranking. You have also compromised the grounds by grounding the battery to the trunk of the car. A 25 year old unibody sheetmetal frame full of tack welds does not make for a good ground path, especially for the ECU, which needs a clean ground for proper voltage references. I wouldn't be surprised if your car doesn't run as well as it did prior to the relocation. Your windows will probably also be slow to go up and your headlights will be dimmer at idle when your HVAC is running. It may take some time for all these issues to arise, but you'll see the things that I mentioned happen eventually.
    #9 RacEoHolic330, Jan 3, 2014
    Last edited: Jan 3, 2014
  10. Thanks for the help everyone. Car runs now.

    So besides re-do my whole set up. How could I remedy the problems that may arise? I'm referring to the slow cranking mainly.

    Also, could this result in my alternator not charging my battery efficiently?
  11. Running a large ground from the battery back to the original grounding location on the engine block behind the power steering pump would be a good start.
  12. Like has been said, a lot: Run large cables. Thick. Huge. What you're experiencing is the inability of run-of-the-mill sized wiring to carry the necessary current the necessary distance. For any given size of wire, the more you increase its length, the more the voltage drops from one end to the other. If you run a larger diameter wire, you'll get less voltage drop for any given length. So you have to counter the additional length with additional diameter in order to keep your voltage intact.
  13. 1/0 welding cable baby!
  14. Rear mounted battery ground wiring. Follow this plan and you will have zero
    ground problems.

    One 1 gauge or 1/0 gauge wire from battery negative post to a clean shiny spot
    on the chassis near the battery. Use a 5/16” bolt and bolt it down to make the
    rear ground. Use a 1 gauge or 1/0 gauge wire from the rear ground bolt to a clean
    shiny spot on the block.

    One 4 gauge wire from the block where you connected the battery ground wire to
    the chassis ground where the battery was mounted up front. Use a 5/16” bolt
    and bolt down the 4 gauge engine to chassis ground, make sure that it the metal
    around the bolt is clean & shiny. This is the alternator power ground.


    The computer has a dedicated power ground wire with a cylindrical quick connect
    (about 2 ½”long by 1” diameter. It comes out of the wiring harness near the
    ignition coil & starter solenoid (or relay). Be sure to bolt it to the chassis ground
    in the same place as you bolted the alternator power ground. This is an
    absolute don’t overlook it item for EFI cars

    Note: The quick disconnect may have fallen victim to damage or removal by
    a previous owner. However, it is still of utmost importance that the black/green
    wires have a high quality ground..

    Picture courtesy timewarped1972 [​IMG]

    Crimp or even better, solder the lugs on the all the wire. The local auto stereo
    shop will have them if the auto parts store doesn't. Use some heat shrink tubing
    to cover the lugs and make things look nice.

    For a battery cut off switch, see
    is the switch is the installation instructions.
    Use the super duty switch and the following tech note to wire it and you will
    be good to go.

    Use the Moroso plan for the alternator wiring and you risk a fire. The 10 gauge wire they recommend is even less adequate that the stock Mustang wiring.

    There is a solution, but it will require about 40' of 18 gauge green wire.

    Wire the battery to the two 1/2" posts as shown in the diagram.

    The alternator requires a different approach. On the small alternator plug there is a green wire. It is the sense lead that turns the regulator on when the ignition switch is in the run position. Cut the green wire and solder the 40' of green wire between the two pieces. Use some heat shrink to cover the splices. See for some excellent help on soldering & using heat shrink tubing.

    Run the green wire back to the Moroso switch and cut off the excess wire. Try to run the green wire inside the car and protect it from getting cut or chaffed. Crimp a 18 gauge ring terminal (red is 18 gauge color code for the crimp on terminals) on each wire. Bolt one ring terminal to each of the 3/16" studs. Do not add the jumper between the 1/2" stud and the 3/16" stud as shown it the
    Moroso diagram.

    How it works:
    The green wire is the ignition on sense feed to the regulator. It supplies a turn on signal to the regulator when the ignition switch is in the Run position. Turn the Moroso switch to off, and the sense voltage goes away, the voltage regulator shuts off and the alternator quits making power.

    The fuse & wiring in the following diagram are for a 3G alternator. The stock alternator uses a dark green fuse link wire that connects to 2 black/orange wires. Always leave them connected to the starter solenoid even if you have a 3G alternator.


    See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Everyone should bookmark this site.

    Ignition switch wiring

    Fuel, alternator, A/C and ignition wiring

    Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs

    Vacuum diagram 89-93 Mustangs

    See the voltage drop section below to help you find any bad connections....
    No Crank checklist for 5.0 Mustangs

    Revised 24-Oct-2013 to update voltage drop figures.

    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 slow crank, 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 .25 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 for help for help troubleshooting voltage drops across connections and components. .


    Voltage drops should not exceed the following:
    200 mV Wire or cable
    300 mV Switch or solenoid
    100 mV Ground
    0.0V Connections
    A voltage drop lower that spec is always acceptable.

    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

    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

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

    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.
  15. I was thinking it was a terrible idea myself, so much more work than just a power cable and computer ground. More junctions always equals more trouble.

    I didn't say anything because i wasn't sure if moving the solenoid to the trunk was some sort of new trend i didn't know about.