G3516B Engines Caterpillar

Electrohydraulic System Oil Pressure (Low)

Usage:

G3516B 7EZ

Probable Causes

The electrohydraulic system's oil level is low.
The electrical circuit for the electrohydraulic oil pressure switch is open.
There is an open circuit in the wiring harness between the electrohydraulic oil pressure switch and the Electronic Control Module (ECM).
The oil pressure for the electrohydraulic system is insufficient.

Recommended Repairs

Check the Electrohydraulic System's Oil Level

Observe the electrohydraulic system's oil level in the sight gauge on the tank.

If necessary, pour oil into the tank until the oil level is between the "ADD" and "FULL" marks on the sight gauge.

Check for oil leaks.

Open Circuit for the Electrohydraulic Oil Pressure Switch

The electrohydraulic oil pressure switch must remain closed while the engine is running. If the switch opens for more than one second, an "E266 (3)" event code is generated and the engine is shut down.

The switch opens at 700 ± 103 kPa (102 ± 15 psi). The switch closes at 1206 kPa (175 psi).

Check for proper operation of the switch. Apply a known pressure to the electrohydraulic system. While you apply the pressure, use a ohmmeter to observe the status of the contact for the switch between pin A and pin B. If the switch does not function properly, replace the switch.

Open Circuit in the Wiring Harness

Use the following procedure to check the harness. Do not operate the engine during this procedure.

Set the engine control to the STOP mode.
Use the Caterpillar Electronic Technician (ET) to observe the "Hydrax Pressure Switch Status".
The status of the switch should be "Open".
Disconnect the 3-pin connector at the electrohydraulic oil pressure switch.
Attach a jumper wire between pin A and pin B on the harness connector.
Use Cat ET to observe the "Hydrax Pressure Switch Status".
The status of the switch should be "Closed".
Continue to observe the "Hydrax Pressure Switch Status". Wiggle the yellow wire and pull on the wire from the harness connector to the ECM P2 connector.
The status of the switch should still be "Closed".
If the "Hydrax Pressure Switch Status" momentarily changes to "Open", the harness has an intermittent circuit.

If there is an intermittent circuit, locate the problem. Make repairs to the harness, when possible. After the harness is repaired, remove the jumper wire from the 3-pin connector. Reconnect the connector.

If the harness cannot be repaired, replace the harness.

Check the Oil Pressure of the Electrohydraulic System

The electrohydraulic oil pressure switch is designed to close at 1206 kPa (175 psi). The switch is designed to open at 700 ± 103 kPa (102 ± 15 psi). The switch must remain closed during engine operation. Use a gauge to check the oil pressure of the electrohydraulic system at the outlet for the hydraulic pump while the engine is cranking or running. Check the pressure while the engine is at normal operating temperature, when possible.

If the pressure is less than 1206 kPa (175 psi), inspect the electrohydraulic system for leaks. Inspect the hydraulic pump. Make repairs, as needed.