DOOR ASSEM (LEFT HAND) 2D3746 - Caterpillar

Illustration 1 g02080415
Schematic for the Service Brake Accumulator Pressure sensor
This diagnostic code is associated with the Service Brake Accumulator Pressure sensor. An FMI 20 means the Brake ECM has determined the data has drifted High, the sensor signal output circuit is above normal.The sensor is an active Pulse Width Modulated (PWM) analog sensor. The sensor sends a PWM voltage signal to the Brake ECM, to indicate the hydraulic pressure in the Service Brake Accumulator unit.Possible causes of this diagnostic code are:
The ECM believes that the Service Brake Accumulator Pressure sensor has Failed in Range.
There is a problem with the physical sensor.
The sensor has failed.
There is a problem with the hydraulic system whereby the Brake accumulators are not draining properly.
The Service Brake Accumulator sensor reports a difference in pressure exceeding 2345 kPa (340 psi), after the Brake Accumulators have completely purged, and the Engine is Not Running.
The Brake ECM may have failed, but is unlikely.Note: Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, that all connections are secure and that all connections are in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 1961 FMI 20 is active before performing this procedure.Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.Test Step 1. CHECK IF THE DIAGNOSTIC CODE REMAINS.
There is a problem with the physical sensor. Expected Result:The physical sensor is fine.Results:
YES - The physical sensor is fine. Proceed to step 2.
NO - The physical sensor is not fine.Repair: Repair or replace the physical sensor.See Testing and Adjusting, KENR8738, "793F BRAKING SYSTEM" or Testing and Adjusting, KENR8374, "797F BRAKING SYSTEM".STOPTest Step 2.
There is a problem with the hydraulic system whereby the Brake accumulators are not draining properly. Expected Result:The hydraulic system whereby the Brake accumulators are draining properly.Results:
YES - The hydraulic system whereby the Brake accumulators are draining properly. Proceed to step 3.
NO - The hydraulic system whereby the Brake accumulators are not draining properly.Repair: Troubleshoot the hydraulic system and the Brake accumulators. Repair or replace the faulty parts.See Testing and Adjusting, KENR8738, "793F BRAKING SYSTEM" or Testing and Adjusting, KENR8374, "797F BRAKING SYSTEM".STOPTest Step 3.
Inspect the contacts of the harness connectors and clean the connectors. Check the wires for damage to the insulation that is caused by excessive heat, corrosion, or chafing.
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the sensor circuit.
Turn the disconnect switch and the key start switch to the ON position.
Clear all inactive diagnostic codes.
Operate the machine.
Check the status of the CID 1961 FMI 20