The Toyota and Lexus charging system is fairly straightforward in both diagnosis and repair. There are two main components of a Toyota or Lexus charging system – the battery and alternator. The battery provides the initial voltage and amperage to crank over the engine, afterwards the alternator takes over in generating the power needed to run the electrical systems in the vehicle.
At idle under minimal load, a Toyota or Lexus’s voltage at the battery should hover at or above 14 volts (many times closer to 14.5). With the headlights, blower motor, and radio on this should change very little. If the voltages begin to drop into the low 13 volts or below (usually rapidly as the loads increase), a failing alternator is to blame.
Lexus Alternator
Seen above is a factory re-manufactured alternator next to a failing unit removed from a 1998 GS400. The output of the failing unit hovered around 11.5 volts and the vehicle would shut down if more than a minimal load was put on the electrical system. In our experience Toyota or Lexus genuine re-manufactured alternators are, even though they come at a premium, the best replacement option. Although aftermarket replacements often come with free lifetime replacement warranties, repeated failures are more common than not. If you are looking for a replacement alternator for a Lexus vehicle, try getting the part number from the Lexus dealership and having your local Toyota dealership check the number against their system. Frequently the Toyota dealer will sell the same part number at a lower price point – the above Lexus replacement alternator was sourced through Toyota at a cost savings of about $50.
As Eden Prairie and Chanhassen’s independent Toyota and Lexus repair specialist, we hope this helps a DIY or curous owner understand Toyota and Lexus alternator failure a bit more. If you think you have a charging or starting system issue, CARspec offers no cost battery and charging system checkout, so give us a call at (952)426-4798 today!
