04 F115 Buzzer

[TownsendsFJR1300]

Just because the battery is charged does NOT mean it will pass a "load test". It may NOT have the amperage(especially when cranking) to "fire up" everything else..

If you have a volt meter, put it across the battery and have a helper turn the key.

12.8 volts, the battery is FULLY CHARGED. If the volts drop say below 10 or more, the battery is toast.

Your fuel system, ignition system, starter, etc, ALL need a good battery to RUN /START.

[boscoe99]

OK I thought I had read some motor had a low voltage warning alarm.
does this F115 have an ignition system that could be affected by low voltage?
maybe that could cause the long crank time before firing up, with a bad battery or bad connection

Yes. The ECU and a bunch of other stuff run off of battery power. If battery power (or system generation electrical power) cannot get to components to do its job the motor won't run correctly.

The ground is very important. People tend to over look grounds for some reason.