FLANGE 1V7503 - 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    
E1251 (1) Interaxle Lock Speed Mismatch    
Activates - when the Automatic Traction Control (ATC) detects abnormal front and rear axle speeds.
Deactivates - when event is cleared and ATC detects normal front and rear axle speeds.
Inputs - Wheel Speed Sensors    
Interaxle Differential (IAD) lock will be disabled
ATC lamp (1) will flash
Warning message displayed on CMPD (2)
   
( 1 ) Automatic Traction Control (ATC) lamp is located on the main cluster display
( 2 ) Caterpillar Multipurpose Display (CMPD)Probable Causes
A stuck interaxle clutch solenoid
Incorrect wheel speed sensor gap due to loose bolts, missing, or broken target ring
A wheel speed sensor failure
An interaxle clutch failure
A broken drive shaftRecommended Actions
Table 2
Interaxle Lock Speed Is Mismatched    
Troubleshooting Test Steps    Results    
1. Check for Codes
A. Connect Cat® ET to the truck.
B. Determine how many E1251 events codes have occurred and when the last event occurred.
C. Check and address any related diagnostic codes.
D. Clear the event and operate the truck in the same manner as when the event was triggered, to see if the event returns.     Result: A related diagnostic code is present.
Troubleshoot any related codes before continuing with this procedure.
Result: E1251 code remains present.
Proceed to Test Step 2.
Result: E1251 code does NOT return.
STOP    
2. Override Interaxle Lock Solenoid and Monitor Interaxle Differential Clutch Pressure
A. Override the interaxle lock solenoid to 100% in Cat® ET and run the engine at 1200 RPM.
B.Connect a 7000 kPa (1000 PSI) pressure gauge to test port 6 and monitor the pressure to the interaxle differential clutch.
The remote test ports are located on the left side of the truck, refer to Testing and Adjusting, UENR0205, "General Troubleshooting Information" for test points and locations.     Result: The interaxle differential clutch pressure is within specification, 2950 150 kPa (425 22 PSI).
Proceed to Test Step 3.
Result: The interaxle differential clutch pressure is not within specification,
2950 150 kPa (425 22 PSI).
Proceed to Test Step 5.    
3. Monitor The Corresponding Wheel Speed In Cat® ET
A. Connect Cat® ET and monitor the status screen for the left and right wheel speeds.
B. Drive the truck in a straight line over good/smooth ground conditions and note the wheel speeds.     Result: Wheel speeds are approximately the same and event code is NOT active.
STOP
Result: Wheel speeds are approximately the same and event code is active.
Proceed to Test Step 5.
Result: Wheel speeds are not approximately the same.
Proceed to Test Step 4.    
4. Check the Suspect Speed Sensor
A. Troubleshoot the speed sensors in question (Differential or Axle Speed Sensor for each axle). Refer to the FMI 08 test procedure for the involved speed sensor in this manual. (CID 3531, 3532, 3533. 3535, 3536, & 3539)
B. Check for incorrect speed sensor gap due to loose bolts.
C. Ensure that the target ring (chopper wheel) is not missing or damaged. Remove speed sensor from