Caterpillar C9 Engine Coolant Level Signal Invalid Fault Code 12 111-2

This instruction show diagnostics steps for Caterpillar C9 engine coolant level signal invalid fault code 12 111-2.

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Conditions Which Generate This Code:

This condition occurs when the coolant level sensor signals indicate a low condition and a normal condition at the same time. The “Coolant Level Sensor” parameter must be programmed to “4-pin”, “2-pin switch”, or “2-wire Float Sensor”before this diagnostic code can occur.

The coolant level sensor is installed by the vehicle’s Original Equipment Manufacturer (OEM). This sensor is an optional sensor for “Engine Monitoring”. Engine monitoring is a programmable feature of the Caterpillar Engine

Control Module (ECM).The sensor is selectable through a customer programmable parameter and the customer programmable parameter may be protected by customer passwords. Some OEM installed coolant level sensors are not connected to the ECM. Do not confuse an OEM installed coolant level sensor that is independent of engine monitoring with the coolant level sensor that is used for engine monitoring.

The customer programmable parameter for the coolant level sensor can be programmed to “4-Pin”, “2-wire float sensor”, or “2-pin switch”. Also, the customer programmable parameter for the coolant level sensor can be programmed to “NO” if the option for the coolant level sensor is not being used.

If the parameter “Coolant Level Sensor” is programmed to “NO”, the coolant level sensor is ignored by the ECM. Conversely, if the parameter is set, then a sensor must be installed. The coolant level is monitored by the engine monitoring system when the parameter “Coolant Level Sensor” is programmed to “4-Pin” or “2-wire float sensor”.

Probable Causes:

1) Coolant level sensor

2) Coolant level sensor harness/connector

3) ECM Connection

4) Wiring between ECM and coolant level sensor

5) ECM Failure

More repair case for Caterpillar machine,please refer to:Caterpillar Machine Repair

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