All the battery output in the existence won't advice provided you don't keep a faultless method.
Your machine's ground wire, again down pat as a "ground cable" or "ground strap," is conceivably the unmarried most earnest wire in its comprehensive electrical process. Consider of the ground wire or cable as your electrical process's foundation, the bridge over which all electrical flow must tread. A damaging ground connexion Testament ruin your electrical method's period, which makes establishing a bad one an further high-priority project.
No-Start Condition
This is one of the aggrandized in evidence signs of a damaging ground, manifesting in similar conduct as a loose battery cable or a dead battery. When you lick to begin your machine, you may hear a unmarried click or a lasting tapping; this is the sound of the starter's solenoid opening or closing, or the sound of the starter's Bendix manage Stirring. The solenoid requires a firm magnitude of voltage to function; whether the ground is dangerous, then the solenoid Testament avail, on the contrary the starter Engine Testament absorb all of the ongoing flow and shut the solenoid off.
Dim or Flickering Lights
You headlights Testament do the same thing as the starter, but will likely dim instead of dying outright. Your DMM should read within about 0.5 volts of your battery with the key in the "Off" position. If you get a voltage reading of anything below 11.5 volts, start looking for a bad ground.
A battery that refuses to take a charge is one sign of a bad ground. The ground is a major part of the battery's charging system, so assuming that you're getting proper voltage output from the alternator wire, and the battery isn't hashed, then you may be looking at a bad ground wire. If the ground wire is loose, then the alternator won't deliver its full power to the battery, particularly at idle.
Testing the Ground
The simplest way to check for a bad ground is to run a continuity test between the battery and the chassis. Disconnect the negative battery cable and connect the probe ends of a digital multimeter -- set to read volts DC -- to the negative and positive battery terminals. Record the reading; you should get something in the neighborhood of 12.6 volts. Next, remove the DMM lead from the positive battery terminal and touch it to the terminal on the disconnected negative battery cable. A constant bad ground -- resulting from a frayed or damaged cable -- will create resistance in the circuit, which will deprive the headlights of power and cause them to dim. This may or may not be the case with xenon arc HID headlights, where a drop in input voltage may fail to initiate the lighting arc altogether. A cable that is simply loose may cause the lights to flicker as the circuit gains and loses the ground.
