If your Porsche Cayenne's starter fails to crank the engine or turns too slowly, your car's engine won't start, leaving you to either walk or bum rides until the problem is fixed. Most of the time, the starter motor is blamed for a no-start condition. Sometimes, however, such an occurrence is hardly the starter motor's fault. Symptoms of a bad starter can mimic other failing components, so it's important to distinguish the difference from other malfunctioning components. Here are some of the issues you need to address to diagnose what problems ail your starter.
If nothing happens when the ignition switch is turned to the start position, it may mean the starter motor has failed, or there may be an opening in the ignition switch, starter circuit wiring, or neutral safety switch. Because slow or labored cranking is a symptom of a bad starter, it's important to make sure that other components are working well to say for sure that something is wrong with the starter.
Check your battery and make sure it has enough voltage to operate the starter; a discharged battery or a badly sulfated one may not be capable of producing enough voltage or amps to start the engine. Also, dim lights mean that the problem has something to do with the battery and not the starter.
The next step would be checking the starter motor itself. If the starter works upon using a jumper to bypass the solenoid (which acts as a relay to route power to the starter from the battery), the problem lies with the solenoid. Replacement is necessary if it is defective or stuck open or closed.
If an engine cranks at normal speed, which is typically at 200 to 250 revolutions per minute, but it refuses to start, the problem doesn't lie with the starter but somewhere else in the vehicle.
A good starter will normally draw 130 to 150 amps when cranking a four-cylinder engine, 175 when cranking a V6, and as much as 200 to 225 amps when cranking a large V8. It will normally draw 60 to 150 amps with no load, and up to 250 amps under load while cranking the engine. If the amp draw is too high, the starter needs to be replaced; the same is true if the starter doesn't achieve the specified rpm.