PINION-DIFFERENTIAL BEVEL 4V8795 - Caterpillar

Table 1
List of Event Codes (EID) For the Chassis ECM (MID 87)    
Code (Level) and Description    Conditions which Generate this Code    System Response    
E1242 (2)
High Interaxle Lock Accumulator Pressure
   
Interaxle lock accumulator pressure sensor signal is higher than expected.
Inputs used in the software mapping for E1242 are:
Interaxle Lock Control Solenoid (must be "ON")
Engine Speed (RPM)
Output Transmission Gear (OTG) Oil Temperature    
ATC will be disabled for the interaxle lock subsystem.
ATC (1) lamp on the main cluster display will flash
CMPD (2) warning message displays    
( 1 ) Automatic Traction Control (ATC) lamp is located on the main cluster display
( 2 ) Caterpillar Multipurpose Display (CMPD)Probable Causes
A blockage or mechanical failure in the interaxle lock subsystem (OTG hydraulics)
A stuck interaxle accumulator charge solenoid
A failed interaxle accumulator pressure sensorRecommended Actions
Table 2
Interaxle Lock Accumulator Pressure Is High    
Troubleshooting Test Steps    Results    
1. Check for Codes
A. Connect Cat® ET to the truck.
B. Determine how many E1242 events codes have occurred and when the last event occurred.
C. Check and address any related diagnostic codes.
D. Clear the E1242 event and operate the truck in the same manner as when the event was triggered, to see if the event returns.
Interaxle Lock Accumulator Pressure should read between the charge cut-in pressure of
3700 kPa (537 psi) and the cut-out pressure of
4800 kPa (696 psi)    
Result: A related diagnostic code is present.
Troubleshoot any related codes before continuing with this procedure.
Result: E1242 code remains present.
Proceed to Test Step 2.
Result: E1242 code does not return.
STOP
   
2. Check for Blockage in the OTG Hydraulics
Check for any blockage or mechanical failure in the OTG hydraulics. Blockage could be in the hydraulic hoses or orifices.
References:.
Schematic, UENR0213, "735B and 740B Articulated Truck Hydraulic System 330-8957-02"
Testing and Adjusting, UENR0205, "Power Train Pressures"
   
Result: No blockage in the OTG hydraulics found
Proceed to Test Step 3.
Result: A blockage in the OTG hydraulics.
Clear and clean the blockage. Perform any necessary repairs.
If the problem is not resolved, proceed to Test Step 3.
   
3. Check for a Stuck Interaxle Accumulator Charge Solenoid
Check the operation of the 277-8863 Interaxle Accumulator Charge Solenoid Valve.
Refer to Troubleshooting, "MID 087 - CID 3543 - FMI 05" in this manual.
   
Result: Interaxle Accumulator Charge Solenoid is OK
Proceed to Test Step 4
Result: A problem is found with the Interaxle Accumulator Charge Solenoid.
Perform the necessary repairs.
Refer to Disassembly and Assembly, UENR0207, "Solenoid Valve (Differential Lock) - Remove and Install" and Disassembly and Assembly, UENR0207, "Solenoid Valve (Differential Lock) - Disassemble and Assemble"
If the problem is not resolved, proceed to Test Step 4
   
4. Check for a Failed Interaxle Accumulator Pressure Sensor.
Check the operation of the 344-7391 Interaxle Lock Accumulator Pressure Sensor (located on the IAD control valve body).
Refer to Troubleshooting, "MID 087 - CID 3542 - FMI 08" in this manual.
   
Result: Interaxle Accumulator Pressure Sensor is OK.
Result: A problem is found with the Interaxle Accumulator Pressure Sensor.
Perform the necessary repairs.
If the problem is not resolved, contact your dealer Technical Communicator (TC) for possible consultation with Caterpillar.