GENERAL AR 1229526 - Caterpillar

Alternator
The R terminal of the alternator is connected to an input of the main display module. The main display module monitors the frequency at the R terminal of the alternator. This tells the main display module if the alternator is rotating. Other Electronic Controls
Some machines have electronic control modules that communicate with the main display module. The Cat Data Link connects these electronic controls together. This connection allows the sharing of information. The following information is an example of the information that is shared: engine oil pressure, harness codes and diagnostic information. For example, an electronic engine control sends the engine speed information to the main display module over the Cat Data Link. In this situation, the engine speed sensor is not a Caterpillar Monitoring System component. If there is a problem with the engine speed sensor, the electronic engine control service manual would be used to troubleshoot the speed sensor circuit.