ENGINE AR-COMPLETE 2833531 - Caterpillar

CONFIDENTIAL TIBU3570-01
TECHNICAL INFORMATION BULLETIN November 20, 2002
WHEEL LOADERS 988G (BNH1-Up)
Component Code: 5084SUBJECT: IMPLEMENT PUMP PRESSURE SENSOR SERVICE CODE MAY INTERMITTENTLY BECOME ACTIVE
PROBLEM: The service code identifying the Variable Implement Pump Oil Pressure Sensor as "Bad" (MID: 82, CID: 864, FMI: 12) may intermittently become active. The electrohydraulic software is programmed to detect malfunctions of this pressure sensor. If the machine appears to be operating well while digging, the sensor may not have failed.
SOLUTION: There are three procedures to determine if the sensor performance is acceptable:
With the engine at high idle, raise the boom fully in order to open the pressure relief for 3-5 seconds and then release the lift lever for 3-5 seconds. Repeating this sequence 5-7 times may clear the active status. Note that the tilt lever must not be touched during the procedure. If the 'active' status clears, the sensor is functioning properly.
Perform 1-F stall speed tests. If the speeds are 1900 ± 30 RPM for 1-F single stall and 1770 ± 40 RPM for 1-F double stall, the sensor is functioning properly. (Double stall must be achieved by powering down the boom without going into float, with loose material mode off and rimpull switch at maximum.)
Monitor the Implement Pump Pressure in Caterpillar Electronic Technician (ET). If the pressure display is near 0 PSI with idle hydraulics and near relief pressure when at relief, the sensor is functioning properly. (Sensor accuracy is ± 6% of relief pressure which means that acceptable output at 0 PSI is ± 300 PSI.)
New software will be required to eliminate false occurrences of this service code. The current software does not properly diagnose the pressure sensor output when the engine speed is below a specific value for extended periods. Using throttle lock above 1600 RPM will prevent this problem. New software is being developed and should be available midyear of 2002.
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