An alternator is a device that uses the engine's rotation to generate electricity for the car's electrical system.

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Versions

The Z32 uses four different alternators.

Non-Turbo
Twin Turbo
1990-1993
80amp
90amp
1994-1996
80amp
90amp
Despite this, they are all interchangeable, though some recommend against putting an 80 amp (NA) alternator in a TT.
The difference between 90-93 and 94-96 alternators was a manufacturing change. While the appearance and size of the alternator changed, they are still interchangeable.
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90-93 alternator on the left, 94-96 alternator on the right. Images from lifeisboost on 300ZXClub. Click images for full-size views.

Operation

Alternators provide electricity to the car while the engine is running. It maintains a charge in the battery and provides electricity to the car's ignition system, headlights, stereo, the entire electrical system. When the engine is stopped (or in the process of starting), power is provided by the battery.

Failure

Alternators are a common point of failure on all cars, and the Z32 is no exception.
When alternators fail (or begin to fail), the following symptoms may present:
  • Dim lights at idle.
  • Car dies while running, with a discharged battery.
  • Battery light/HICAS Light/other seemingly unrelated warning lights illuminate on the dash while the car is running.
  • Battery showing ~12V or less while running. (Should be ~13.5V with the car running).

Should the alternator fail or begin to fail while the car is running, electricity will begin draining from the battery. Once the battery voltage becomes too low, the car's electrical systems (including it's ignition system) will stop operating.

A common misconception is that a car without enough power to crank over and start can be caused by a bad alternator. In reality, the battery provides power for the car when starting, and the alternator simply provides power when the car is running. While a failing alternator can fail to charge the battery while the car is running, this will become evident while the car is running. Once the car is off, the battery's job is to maintain enough energy to start the car next time.

Power Steering Leak

One of the most common causes for failure of the Z32's alternator is a leaking high-pressure power steering hose. This is the hose that carries (you guessed it) high pressure power steering fluid from the power steering pump (mounted directly above the alternator) to the steering rack. As it's under high pressure, this line is prone to develop leaks over the years. The fluid drips onto the alternator, allowing oil and grime to build up inside the alternator, leading to its eventual failure.

As a form of cheap insurance, some owners install some plastic conduit around the high pressure line. Should it start leaking, this helps to channel power steering fluid down to the bottom of the engine bay without affecting the alternator.

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