GM-GMC: Electrical, transient voltage spikes, jumper cables

Question
Will jumping a late model chevy truck damage the alternator, assuming the connections are made correctly?

Answer
In most cases, no, the alternator should not be affected by jump starting procedures.

However, there is always a risk to the electrical systems of both vehicles due to transient voltage spikes.  Just about everyone is familiar with surge supressors used on computers.  These supressors keep very short, but very high, voltage spikes from damaging the electronic components inside the computer.

The vehicles undergoing a bettery jump procedure can also experience transient spikes when the jumper cables are connected.  Though the voltage is lower, the damage can be just as bad.  Voltage regulators, which are now built into most alternators, can be destroyed by the transient voltage spikes (or by incorrectly connecting the jumper cables).

Also note that newer alternators have safety circuits in them to prevent them from charging a battery that too low a voltage.  What might seem like a bad alternator could really be a battery that needs to be recharged using an external battery charger.

If in doubt, remove the battery cables from the vehicle and then remove the alternator.  Most auto parts stores will test the alternator for free.