Introduction
This page provides information in regards to Toyota alternators basic operation and wiring.
This page will focus on the Toyota alternator with inbuilt regulator, however some information maybe valid for generic alternators.
Alternator Function
The function of the alternator is to supply electrical energy to support the electrical loads in the vehicle's electrical system. These loads include the electronic fuel injection system, radio, lights, defogger and more. As a number of these loads are critical (i.e. fuel injection system) it is important that the system functions well.
It is worth noting that under normal operating conditions the alternator is responsible for supplying all of the electrical energy required for the vehicle systems, the battery is only used to help in filtering out voltage spikes and supplying small amounts of extra current during short duration events such as when heavy electrical loads are turned on (e.g electric engine cooling fans turning on).
Of course the alternator is also responsible for charging the battery after the engine has been started, to replace the electrical energy that used to start the engine.
Alternator Operation
In general terms the alternator is driven by the engine to turn mechanical energy into electrical energy. I won't explore the details in regards to how the alternator generates electrical energy from mechanical energy in this article, however I will briefly explore how and why the output of the alternator is regulated.
As the alternator is required to (ideally) output a fixed voltage regardless of the electrical load (current) of the vehicle system and the engine RPM it makes sense that there needs to be a system that controls the alternator to ensure that the alternator voltage output remains stable and consistent across the wide range of operating conditions that are likely to be experienced.
The alternator 'regulator' is the component that is responsible for controlling the alternator to achieve the desired operation.
Alternator with Inbuilt Regulator
This section will discuss the Toyota alternator with inbuilt regulator and the wiring associated with the alternator and regulator.
Since the early 1980's (~1983) Toyota have used an alternator with an inbuilt regulator, prior to this the regulator was a module that was mounted external to the alternator. As mentioned previously this page will focus on the alternator with inbuilt regulator predominately.
Alternator with Inbuilt Regulator Pinouts
There are a number of different pinouts for Toyota alternators with inbuilt regulators.
Alternator Regulator 'S' Terminal
The alternator regulator 'S' terminal is used to 'Sense' the battery voltage at the battery, hence the abbreviation 'S'.
The 'S' input is a very important input to the regulator as it serves as the basis for the control of the alternator output.
To describe why the 'S' pin is of importance
Symbol |
Definition |
Input/Output |
What |
Why |
How |
S |
Battery Voltage Sense
|
Input |
This pin is used to determine sense the voltage at the battery
|
The voltage at the battery is the main parameter that the regulator uses to control / regulate the alternator output.
|
This pin is connected to the positive terminal of the battery at all times, in most wiring arrangements via a 7.5A fuse marked ALT-S (Alternator Sense).
|
Alternator Regulator 'L' Terminal
The alternator 'L' terminal is used to turn the alternator charge warning light located in the dash on when the regulator has detected that the alternator is not charging.
Symbol |
Definition |
Input/Output |
What |
Why |
How |
L |
Alternator Charge Warning Light
|
Output |
This pin is used to determine turn the alternator charge warning light ON / OFF
|
If the alternator regulator detects that the alternator has failed it can indicate this to the driver so action can be taken.
|
This pin is Grounded by the regulator as required to turn the alternator charge warning light ON. The alternator charge warning light should be wired with one side of the light connected to battery voltage (Ignition Switched) and one side of the light connected to this regulator pin. Light ON = Error Condition, light OFF = Normal. |
Alternator Regulator 'IG' Terminal
The alternator 'IG' terminal is used to turn the alternator on when the engine is on. If the regulator didn't have a signal to turn on / off it would drain the battery.
Symbol |
Definition |
Input/Output |
What |
Why |
How |
IG |
Ignition Switch |
Input |
This pin is used to determine if the ignition is ON. |
The alternator regulator is turned on by this signal. |
This pin is connected to battery voltage when the ignition switch is in RUN and CRANK positions. |
Views:
Comments (0)
You don't have permission to comment on this page.