Checking Low Oil Pressure Warning SystemWith the ignition off, the low pressure switch (0.3 bar) is closed (complete circuit to ground). When the ignition is turned on, the indicator flashes (no oil pressure). When the engine is started and oil pressure rises, it opens the switch (opening the ground circuit), and the indicator goes out. With insufficient oil pressure or a stuck switch, the indicator will continue to flash. The switch opens and closes at specific pressures. See Testing Oil Pressure Switches. To quick-check the pressure switch, simulate a closed switch by removing the blue/black wire and grounding it. With the ignition on, the indicator should flash. If not, the problem is in the circuit or the indicator. If the indicator flashes only when tested in this way, replace the switch. If the indicator flashes with the engine running, and the oil pressure tests OK, remove the blue/black wire from the switch with the engine running. The indicator should go out. If not, the circuit is shorted to ground between the wire and indicator. If the indicator does go out, the switch is stuck closed and should be replaced. |
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