COVER-FRONT 2598098 - 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    
E1501 (2) High Interaxle Lock Supply Pressure     Interaxle lock supply pressure sensor signal is higher than expected.
Inputs used in the software mapping for E1501 are:
Interaxle Lock 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 Output Transfer Gear Lube Oil Relief Solenoid Valve
A failed Interaxle Lock Pressure SensorRecommended Actions
Table 2
Interaxle Lock Supply Pressure Is High    
Troubleshooting Test Steps    Results    
1. Check For Codes
A. Connect Cat® ET to the truck.
B. Determine how many E1501 events codes have occurred and when the last event occurred.
C. Check and address any related diagnostic codes.
D. Clear the E1501 event and operate the truck in the same manner as when the event was triggered, to see if the event returns.
Interaxle Lock Supply Pressure is
3700 200 kPa (537 29 psi).     OK: Event code E1501 is not present, however a related diagnostic code is present.
Troubleshoot any related codes before continuing with this procedure.
Result: E1501 code remains present.
Proceed to Test Step 2.
Result: E1501 code does not return.
STOP    
2. Check For Blockage In The Output Transfer Gear (OTG) Hydraulics
A. Check for any blockage or mechanical failure in the OTG Hydraulics. Blockage could be in the hydraulic hoses or orifices. .
References: Testing and Adjusting, UENR2346, "Power Train Pressures".     OK: No blockage in the OTG hydraulics found.
Proceed to Test Step 3.
NOT OK: A blockage has been located in the OTG Hydraulics.
Repair: 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 Output Transfer Gear Lube Oil Supply Solenoid
A. Check the operation of the 295-8358 Output Transfer Gear Lube Oil Supply Solenoid Valve.
Refer to Troubleshooting, "MID 087 - DTC 3543 - 5" in this manual.
    OK: Output Transfer Gear Lube Oil Supply Solenoid Valve is operating correctly.
Proceed to Test Step 4.
NOT OK: A problem is found with the Output Transfer Gear Lube Oil Supply Solenoid Valve.
Repair: Perform the necessary repairs. Refer to Disassembly and Assembly, UENR2351, "Solenoid Valve (Differential Lock) - Remove and Install" and Disassembly and Assembly, UENR2351, "Solenoid Valve (Differential Lock) - Disassemble and Assemble".
If the problem is not resolved, proceed to Test Step 4    
4. Check for a Failed Interaxle Lock Supply Pressure Sensor
A. Check the operation of the 344-7391 Interaxle Lock Supply Pressure Sensor (located on the IAD control valve body).
Refer to Troubleshooting, "MID 087 - DTC 3542 - 8" in this manual.     OK: Interaxle Lock Supply Pressure Sensor is