Refer to Systems Operation, Testing and Adjusting, "Machine Preparation for Troubleshooting" before you perform any testing and adjusting or troubleshooting.
Prior to starting with checks on the retarder, use Caterpillar ET in order to diagnose any fault codes that may be present. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, RENR3442, "Power Train Electronic Control System".
Checking The Retarder
Refer to Operation and Maintenance Manual, SEBU7347 for details of the operation of the retarder control.
Before carrying out checks on the retarder, use ET in order to switch off the "Throttle Deactivated Retarding" function of the ECM.
The output speed of the torque converter is a more accurate gauge of retarder performance than the speed of the engine. This is due to slip in the torque converter.
- Connect the computer to the diagnostics socket by using the communications adapter. The diagnostics socket is located at the right side of the seat for the operator.
 | |
| Illustration 1 | g00764819 |
- Start Electronic Technician and monitor the torque converter output speed.
- Start the engine and ensure that the parking brake is engaged. Allow the engine and the transmission to reach the normal operating temperature.
- Ensure that the transmission is in neutral and run the engine at high idle.
- Move the retarder control to the MINIMUM position. Observe:
- The retarder indicator must be illuminated.
- The torque converter output speed should be observed to fall.
- The retarder indicator must be illuminated.
- Move the retarder control to MEDIUM and move the retarder control to MAXIMUM. The different positions of the retarder control should have a different effect upon the torque converter output speed.
 | |
| Illustration 2 | g00765177 |
Retarder control | |
 | |
| Illustration 3 | g00765167 |
Retarder indicator | |
- Reduce the engine speed to approximately 1000 rpm. Observe:
- The retarder remains engaged.
- The retarder indicator is illuminated.
- The retarder remains engaged.
- Move the retarder control to the OFF position. Observe:
- The retarder indicator is no longer illuminated.
- The torque converter output speed should increase.
- The retarder indicator is no longer illuminated.
- Stop the engine.
- Once the checks have been completed, switch on the "Throttle Deactivated Retarding " function of the ECM.
If any problems were encountered with the above procedure, refer to Systems Operation, Testing and Adjusting, "Retarder Troubleshooting".
Retarder Hydraulic Control Valve
Check that the relief pressure of the torque converter outlet is satisfactory. Check that the oil cooler inlet pressure is satisfactory. Refer to Systems Operation, Testing and Adjusting, "Power Train Pressures".
Check that the oil pressure of the outlet of the retarder is satisfactory. If the oil pressure of the outlet of the retarder is below the specified level, and the relief pressure of the torque converter outlet is satisfactory, it is possible that the spool in the retarder hydraulic control valve is not moving.
Check the pressure of the oil in the retarder actuation valve when each of the three positions of the retarder control are selected.
If the pressure of the oil in the retarder actuation control valve is satisfactory for all three positions of the retarder control, the spool in the retarder hydraulic control valve may be sticking. Remove the retarder hydraulic control valve and inspect the condition of the spool. Refer to Disassembly and Assembly, "Retarder Hydraulic Control Valve - Remove and Install".
If the pressure of the oil in the retarder actuation valve is unsatisfactory, there may be a fault with the solenoid in the retarder actuation valve.