When to check the field wire for an alternator?
For example, if the alternator is not putting out any power, check the field wire before ordering a new alternator. It is just easier to fix simple things, even if it is not always easier to find simple problems.
Is the field coil powered by the alternator?
The field coil is powered by a box called Powertrain Control Module, and there are 3 fuses that might be of interest, numbered 6, 19, and 26 according to the schematic (see below). If these are all good, then you need to check the wiring between the PCM and the alternator, or the PCM itself may have a problem.
Why does my alternator have a high resistance reading?
Mechanical noise is different than radio noise, so turn your radio off if you aren’t sure of the origin of the noise. On alternators with F1 and F2 terminals, you will need to connect one lead of the meter to each terminal. The resistance reading is a little high because this alternator has been sitting on a shelf for several years.
How can you tell if an alternator is not internally grounded?
If there is no or almost no resistance, you have a short inside the alternator. You should expect to see at least 4 to 6 ohms between the field terminal and ground, assuming a 12-volt system. In some cases, the field is not internally grounded. You can tell this by the existence of two field terminals on the alternator (usually marked F1 and F2).
For example, if the alternator is not putting out any power, check the field wire before ordering a new alternator. It is just easier to fix simple things, even if it is not always easier to find simple problems.
The field coil is powered by a box called Powertrain Control Module, and there are 3 fuses that might be of interest, numbered 6, 19, and 26 according to the schematic (see below). If these are all good, then you need to check the wiring between the PCM and the alternator, or the PCM itself may have a problem.
Mechanical noise is different than radio noise, so turn your radio off if you aren’t sure of the origin of the noise. On alternators with F1 and F2 terminals, you will need to connect one lead of the meter to each terminal. The resistance reading is a little high because this alternator has been sitting on a shelf for several years.
If there is no or almost no resistance, you have a short inside the alternator. You should expect to see at least 4 to 6 ohms between the field terminal and ground, assuming a 12-volt system. In some cases, the field is not internally grounded. You can tell this by the existence of two field terminals on the alternator (usually marked F1 and F2).