Car won't start, when connected to my charger it does start. My battery is fully charged. My dash battery guage is not registering. Is there an alternator light? What do you think the problem is?

Check the ground wire to the engine block.

Ok, checked the ground cable, I'm suprised its not connected to the block, but to the starter.
Some other symptoms, maybe you could comment on.
The Battery is fully charged, the terminals have been cleaned with baking soda, and wire brushed and has good contact.
Took the car out last night, started and stopped a couple of times, and all was well.

Got up this morning...click click, no start. did a gravity test on the battery and is fully charged.

Pulled cables off, and put back on, still click, click.

Attached the charger for 5 minutes, removed the charger. Started up fine. turned off, and on again, started up fine.
5 minutes later it would not start...
What is the charger doing to make a connection?

Next time it won't start, use an insulated screw driver and jump the terminals on the solenoid. If it turns over, replace the solenoid.
I had a similar problem when I replaced the battery cables with the cheapo AutoZone ones. Put the more expensive terminal ends on and works fine so far.....

I tried shorting out the solonoid, just sparks...any other Idea's?

I did replace both Battery Cables, they were original equipment, and in real bad shape, and thought by the looks of them it was the problem...but wasn't.

Using a soloinoid testing chart, with my meter I went through all the following stems, please have patience with me for this detail;


Step 1: Check the voltage on the battery side of the solenoid
as shown on the left. The reading should be the same as the
battery reading (12.6V = Full Charged Battery).
My Reading is 6.14
Step 2: With the voltmeter still connected, turn the key to the
start position and read the voltage.The voltage should not drop
below 10.0 volts on this terminal. If the voltage drops below
10.0 volts, The battery cable should be cleaned or replaced If the
reading is 10.0 volts or more.
My Reading is 5.73
Step 3: Keep the negative voltmeter lead on the metalbase
of the solenoid and move the positive voltmeter lead to the
terminal marked “S” on the solenoid. Turn the key to the start
position and read the voltage. The Voltage could read a little
lower than the previous reading but should never be below
10.0 volts. If the voltage is lower than 10.0 volts, You must
troubleshoot the start circuit (ignition switch, voltage supply
to the ignition switch, neutral safety switch).
My Reading is .006
Step 4: Move the positive voltmeter lead to the battery
terminal on the solenoid and the negative voltmeter lead to
the terminal that the starter cable is attached. Turn the key
to the start position and read the voltage. The voltage should
read no more than .3 volts. If the reading is more than .3 volts
the contacts have excessive resistance and the solenoid should
be replaced.
My Reading is 5.75
Step 5: Some solenoids use a relay terminal on the solenoid to
power fuel pumps or supply full battery voltage to ignition coils
when the starter is activated. This terminal is usually marked “I”
or “R”. Connect the voltmeter a shown. Turn the key to the start
position. You should read no more than 0.3 volts. If you have
more than 0.3 volts the solenoid should be replaced.
I can’t see where the terminal was, is there an ignition coil?
So what do you think...is it my Solonoid?

I'm having a hard time visualizing how the solenoid is set up on the Mustang. I believe there is a positive cable going from the battery to the solenoid, and then another from the solenoid to the starter. If the engine wont crank and you jump the two cables together at the solenoid you will be bypassing the solenoid completely and the car should crank. If its cranks then you know the solenoid is toast. However, with the voltage readings you're getting (especially that first one) it sounds like there is either a problem with the battery or the cable. You're getting only 6 volts where there should be 12.

If you check the voltage across the battery terminals is it 12+ volts? If so then try connecting the negative lead (of the voltmeter) to the negative battery terminal and the positive lead to the positive cable on the solenoid. It should still read the same voltage as before (12+ volts). If not then it would mean the problem is in that positive cable.

Also next time it wont start try cranking it and then immediately check the battery voltage. If its below 12v then the battery is toast.

You are right, the battery is toast... even though the cells registered well, under a load the voltage dropes big time, thanks for all you do to help us.
Paul

Glad to hear you found the problem!