The Low Idle RPM May Drop Below Specifications Caterpillar

The Low Idle RPM May Drop Below Specifications

Usage:

EXCAVATORS312B (9GR, 2NS),
312B L (8JR, 3FS) EXCAVATORS

Problem:

The low idle setting for the engine may drop below minimum specifications on some of the listed excavators. The symptom may appear as a customer complaint of cab vibration or low idle instability. The problem may be temporarily corrected when the governor actuator is recalibrated. In some instances, the symptom will appear again and recalibrating the governor will not correct the problem at all.

Solution:

Perform the following procedure in order to correct the problem.

Perform a governor calibration with the procedure listed in RENR1998, Systems Operation Testing & Adjusting Module, for Engine and Pump Electronic Control System, Page 42. This module is found in Service Manual SENR9220. Exit the electronic controller service mode after the calibration is completed. Perform the following procedure in order to set a fixed low idle.

1. Set the engine dial speed at Position 1.

2. Enter the following password, "100357", through the monitor panel. The service code, "90-1-0", will appear.

NOTE: If the speed dial is in any other position and is returned to the speed dial Position 1 after the password is entered, the code, "90-1-85", will appear.

3. Refer to the Testing & Adjusting Module to identify the switches on the monitor panel that are used to set service code. Change code "90-1-85" or code "90-1-0" to the new code "90-1-90". The service code change will set the low idle to 900 rpm.

4. Press the ALARM CANCEL button to save this value.

NOTE: If the ALARM CANCEL button is not pressed, the value will not be saved when you leave the service mode.

5. Exit this service mode.

6. Check the LOW IDLE RPM value by entering the normal service mode and checking service code "12".

NOTE: DO NOT RECALIBRATE the governor actuator after setting a fixed low idle. The recalibration will cancel the fixed low idle setting.

Engineering is currently investigating the root cause in order to establish a solution for this problem. If you experience machine failures with the symptoms noted in this TIB, please contact:

BCP Excavator Product Support

Phone:

R. Don Allen (919) 550-3092

OR

Jim Bathrick (919) 550-3093

COPYRIGHT 1999 CATERPILLAR ALL RIGHTS RESERVED

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