SYMPTOM RELATED DIAGNOSTICS

LOW OIL PRESSURE WITH DRIVER ALARM (continued)

Test 8

Checking the pressure sensor

1.Turn the ignition key to the OFF position.

2.Reinstall the circuit breaker.

3.Turn the ignition key to the ON position, start and idle the engine.

If the pressure exceeds 5 psi at idle, compare the pressure on the gauge with the pressure recorded by V-MAC II using a diagnostic tool. If the pressures agree within 3 psi, run the engine to high idle and compare the two pressures again. If the pressures still agree within 3 psi, there no longer is a problem. Retest to be sure the problem has been corrected.

If the pressure on the gauge does not reach or exceed 5 psi after 15 seconds of idling, STOP THE ENGINE. The oil pressure sensor works properly but there is still a mechanical problem resulting in low oil pressure, such as a blocked passage or filter. Locate and repair the problem. Retest to be sure the problem has been corrected.

If the pressures do not agree at any time within 3 psi, proceed to Test 17.

Test 17

Electrical checks

1.Turn the ignition key to the OFF position.

2.Disconnect the engine harness from the oil pressure sensor.

3.Measure the resistance from harness connector pin A (the ground [ ] line) to a good ground.

If the resistance between the ground [ ] line and ground is greater than 20 ohms, make sure that there are no electrical devices (lights, heater motors, etc.) running in the cab. Find a new good ground and try again. If the resistance is still greater than 20 ohms, there is a break or bad connection somewhere between the harness connector pin A and J1A connector pin G2. Check for corroded terminals at the harness, bulkhead connector and J1A connector, and for evidence of damaged wiring.

If the resistance is less than 20 ohms, proceed to Blink Code 1-1 or 1-2 (Engine Oil Pressure Sensor).

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