Low Oil Pressure Indicator

WARNING: This page is about a different car, the 2017 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.

The low oil pressure indicator gives an indication to the vehicle operator when the engine oil pressure reading reflects a condition requiring immediate attention. This indicator is controlled by a transistor on the Instrument Panel Cluster (IPC) circuit board based upon IPC programming and electronic messages received by the cluster from the PCM over the Controller Area Network (CAN) data bus.

The low oil pressure indicator Light Emitting Diode (LED) is completely controlled by the IPC logic circuit, and that logic will only allow this indicator to operate when the IPC receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the LED will always be OFF when the ignition switch is in any position except ON or START. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The IPC will turn ON the low oil pressure indicator for the following reasons:

Engine Oil Pressure Low Message - Each time the cluster receives an electronic engine oil pressure message from the PCM indicating the pressure is about 6.9 kPa (1 psi) or lower, the low oil pressure indicator will be illuminated. The indicator remains illuminated until the cluster receives a message from the PCM indicating that the pressure is above about 6.9 kPa (1 psi), or until the ignition switch is turned to the OFF position, whichever occurs first. The IPC will only turn the indicator ON in response to low engine oil pressure if the engine speed is greater than zero.

The PCM continually monitors the engine oil pressure sensor to determine the engine oil pressure. The PCM then sends the proper messages to the IPC. For further diagnosis of the low oil pressure indicator or the IPC circuitry that controls the LED. Refer to DIAGNOSIS AND TESTING .