3406E, C-10, C-12, C-15, C-16 and C-18 On-highway Engines Caterpillar

The engine retarder solenoids are usually factory installed at Caterpillar and the switches are installed by the vehicle OEM. The ECM directly drives the retarder solenoids, eliminating OEM installed relays and circuit protection. The ECM reads the status of the OEM installed engine retarder switches in order to determine the following modes of operation:

• OFF

• Low

• Medium

• High

Operation of the retarder solenoids is inhibited during undesirable engine operating conditions.

All of the following conditions must be met in order to ensure the proper retarder operation regardless of the settings of the customer specified parameters:

• Engine speed is above 800 rpm.

• The "Accelerator Pedal Position" is less than 8 percent.

• The clutch pedal is released.

Additional factors may affect retarder operation. The additional factors are based on the programming of certain customer specified parameters. The following parameters may affect retarder operation:

• "Engine Retarder Mode"

• "Auto Retarder In Cruise"

• "Auto Retarder In Cruise Increment"

• "Engine Retarder Minimum Vehicle Speed"

• "Engine Retarder Minimum Vehicle Speed Type"

• "Engine Retarder Delay"

Note: If the "PTO Configuration" is programmed to Cab Switches, Remote Switches, or Remote Throttle, the engine retarder is disabled whenever the PTO On/Off circuit is on.

When the Cruise Control On/Off Switch is in the ON position, the following conditions exist:

"Engine Retarder Mode"

When the cruise control On/Off switch is on, this parameter provides two special options that allow the engine retarder to be operated only after the driver has depressed the service brake pedal. The two modes of operation that follow are customer programmable:

• The "Coast" mode engages the engine retarder when the driver depresses the service brake pedal. The retarder disengages when the driver releases the service brake pedal.

• The "Latch" mode engages the retarder when the driver depresses the service brake pedal. The retarder remains engaged until the control detects a change in a control input. The following actions are examples of a change in a control input:

• The throttle is depressed.

• The clutch pedal is depressed.

• The engine speed drops below 800 rpm.

The third option for the engine retarder parameter is "Manual". The Manual mode operates in the same manner regardless of the position of the cruise control On/Off switch. The driver is not required to depress the service brake pedal in order to initiate the engine retarder. This is required in the Latch mode and the Coast mode.

Note: The Latch mode and the Coast mode are customer programmable options. The Latch mode and the Coast mode determine engine retarder operation only when the cruise control switch is in the ON position. The Latch mode and the Coast mode do not determine engine retarder operation when the engine is active in cruise control. Latch mode and Coast mode require the initiation of the service brake before acting. The action of the service brake disengages the cruise control.

"Auto Retarder In Cruise"

This parameter allows the engine retarder to activate while the engine is in cruise control in order to maintain the cruise set speed. The "Auto Retarder in Cruise" option still requires the engine retarder switches to be in the ON position. The "Auto Retarder in Cruise" option will only activate the engine retarder to the level of braking that is determined by the switch setting. The "Auto Retarder in Cruise" parameter is a vehicle speed above the cruise set speed. When the vehicle speed that is above the cruise set speed is met, the ECM will send a signal in order to begin engaging the engine retarder.

At this vehicle speed, the engine retarder will activate at the low level. The Medium and High braking levels will be activated at the programmed "Auto Retarder in Cruise Increment". This assumes that the engine retarder switches are set at the high level. The "Auto Retarder in Cruise" affects the engine retarder solenoids that are driven directly from the ECM engine harness connector P2 terminal 9, terminal 10 and terminal 11.

"Auto Retarder In Cruise Increment"

The "Auto Retarder in Cruise Increment" parameter determines the increment in kilometers per hour (km/h) or miles per hour (mph) when the higher levels of engine retarder will activate. This feature requires the "Auto Retarder in Cruise " parameter to be programmed above 0 mph.

"Engine Retarder Minimum Vehicle Speed"

This parameter determines the minimum vehicle speed limit for the engine retarders to turn ON. When this parameter is programmed to "0" the retarder will operate at all vehicle speeds.

"Engine Retarder Minimum VSL Type"

The "Engine Retarder Minimum VSL Type" defines the use of the "Engine Retarder Minimum Vehicle Speed" parameter. The "Engine Retarder Minimum VSL Type" provides the following two options:

• Hard Limit

• Soft Limit

If the "Engine Retarder Minimum VSL Type" is programmed to the Hard Limit, the engine retarder will turn off when the value that is programmed into the "Engine Retarder Minimum Vehicle Speed" is reached.

If the "Engine Retarder Minimum VSL Type" is programmed to the Soft Limit, the engine retarder will remain in the ON position below the value that is programmed in the "Engine Retarder Minimum Vehicle Speed". The engine retarder will remain in the ON position until the parameters that would normally turn off the engine retarder are met. The retarder cannot be activated when the vehicle speed is below the "Engine Retarder Minimum Vehicle Speed".

This parameter requires the "Engine Retarder Minimum Vehicle Speed" parameter to be programmed above 0 mph.

"Engine Retarder Delay"

The "Engine Retarder Delay" parameter provides a programmable delay after all basic conditions that are required to turn on the retarder are met. Once the conditions are met, the ECM will delay the activation of the retarder by the programmed additional time. The programmable range is 0.0 to 3.0 seconds in 0.1 second increments.

Other Control Systems

Trucks that are equipped with SAE J1922 systems may also control the engine retarder. For ABS systems that do not use SAE J1922 with the engine retarder solenoids, a relay may be connected into the retarder switch circuit in order to disable the engine retarder or a relay may be connected into the clutch switch circuit in order to disable the engine retarder.

Note: If the vehicle is equipped with an Anti-Lock Brake System (ABS), the vehicle may have an additional relay in the switch circuit for the engine retarder switches or the clutch switch. This is installed so the ABS system can turn off the engine retarder, if necessary. The relay should have normally closed contacts. The ABS system can not turn on the engine retarder. The Caterpillar ECM must still activate the retarder.

Note: If the "Transmission Style" parameter is programmed to Eaton Top 2, normal engine retarder operation can be inhibited by the ECM. Normal engine retarder operation can be inhibited by the ECM when the driver is attempting to make a shift in Top 2 mode in order to provide better control of torque during the process of shifting.

"Retarder Brake Test"

The "Retarder Brake Test" should be used to assist in troubleshooting problems in the circuit for the engine retarder. The ECM will only detect shorts in the circuit for the engine retarder when the test is active. "Current high" diagnostic codes (short circuits) will be logged once the test has been deactivated. The ECM will only detect opens in the circuit for the engine retarder when the test is not active. The test must be activated and then deactivated before the ECM will detect an open circuit. "Current low" diagnostic codes (open circuits) will be active once the test has been deactivated.

Illustration 1	g00645615
Schematic for engine retarder (compression brake)

Illustration 2	g00645629
Terminal locations for ECM

Illustration 3	g00999340

Test Step 1. Check Electrical Connectors and Wiring

1. Thoroughly inspect the J1/P1 and J2/P2 ECM connectors, the injector connector for the valve cover J300/P300 and the firewall bulkhead connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

2. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the connections for the engine retarder solenoids and the engine retarder switch:

3. Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).

4. Check the harness and wiring for abrasion and pinch points from the accelerator pedal position sensor to the ECM.

Expected Result:

All connectors, pins and sockets should be completely coupled and/or inserted and the harness and wiring should be free of corrosion, abrasion or pinch points.

Results:

• OK - Proceed to Test Step 2.

• Not OK -

  Repair: Perform the following repair:Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.

  STOP

Test Step 2. Check for Diagnostic Codes

1. Connect the Caterpillar Electronic Technician (Cat ET) to the data link connector.

2. Place the engine retarder switch in the High position.

3. Turn the key switch to the ON position.

4. Check for active diagnostic codes and logged diagnostic codes that are related to the engine retarder. Clear any logged diagnostic codes that are related to the engine retarder.

5. Access the "Retarder Brake Test" in the "Special Tests" under the "Diagnostics" menu.

6. Start the test.

7. Check for active diagnostic codes that are related to the engine retarder.

8. Stop the test.

9. Check for active diagnostic codes that are related to the engine retarder.

Expected Result:

There is an active "current high" diagnostic code (short circuit) when the test is active. There is an active "current low" diagnostic code (open circuit) when the test is not active.

Results:

• Current Low (Open) - There is an open in the circuit for the engine retarder. Proceed to Test Step 3.

• Current High (Short) - There is a short in the circuit for the engine retarder. Proceed to Test Step 6.

• No Codes - There are no diagnostic codes that are related to the engine retarder. Proceed to Test Step 9.

Test Step 3. Create a Short Circuit at the Valve Cover

1. Turn the key switch to the OFF position.

2. Disconnect the J300/P300 Injector connector on the valve cover base.

3. Connect a jumper wire between the terminal for the suspect circuit and P300:7 (Retarder Solenoid Common).
   • P300:9 (LOW/HI Retarder Solenoid)

   • P300:11 (MED/HI Retarder Solenoid)

4. Turn the key switch to the ON position.

5. Access the "Retarder Brake Test" in the "Special Tests" under the "Diagnostics" menu.

6. Start the test.

7. Check for active diagnostic codes that are related to the engine retarder.

8. Stop the test.

9. Check for active diagnostic codes that are related to the engine retarder.

Expected Result:

A "current high" diagnostic code (short circuit) is active when the jumper wire is in place and the "Retarder Brake Test" is active.

Note: A "current low" diagnostic code (open circuit) will be active when the jumper wire is removed and the test is not active.

Results:

• OK - The harness between the ECM and the valve cover base is OK. Proceed to Test Step 4.

• Not OK - A "current high" diagnostic code (short circuit) was not active. There is a problem between the ECM and the valve cover base. Proceed to Test Step 5.

Test Step 4. Create a Short Circuit at the Engine Retarder Solenoid

1. Turn the key switch to the OFF position.

2. Remove the valve cover(s).

3. Disconnect the wires for the suspect solenoid. Insert a jumper wire between the two wires for the suspect solenoid.

4. Turn the key switch to the ON position.

5. Access the "Retarder Brake Test" in the "Special Tests" under the "Diagnostics" menu.

6. Start the test.

7. Check for active diagnostic codes that are related to the engine retarder.

8. Stop the test.

9. Check for active diagnostic codes that are related to the engine retarder.

Expected Result:

A "current high" diagnostic code (short circuit) is active when the jumper wire is in place and the "Retarder Brake Test" is active.

Note: A "current low" diagnostic code (open circuit) will be active when the jumper wire is removed and the test is not active.

Results:

• OK - There may be a problem with the engine retarder solenoid.

  Repair: Temporarily connect a new engine retarder solenoid.If the new solenoid fixes the problem, reconnect the suspect solenoid.If the problem returns, permanently replace the solenoid.Verify that the repair eliminates the problem.

  STOP

• Not OK - There is a problem in the harness under the valve cover.

  Repair: Inspect the wiring between the valve cover base and the engine retarder solenoids.Insert a jumper wire between the supply wire for the suspect solenoid and chassis ground.Repeat this Test Step.If there is still a "current low" diagnostic code (open circuit), the problem is the supply wire.If there is a "current high" diagnostic code (short circuit), the problem is the common wire.Repair the wiring or replace the wiring.Verify that the repair eliminates the problem.

  STOP

Test Step 5. Create a Short Circuit at the ECM

1. Turn the key switch to the OFF position.

2. Disconnect the J2/P2 ECM connector.

3. Connect a 140-2266 Cable (Seventy-Pin Breakout) to the J2 ECM connector. Do not connect the P2 ECM connector.

4. Connect a jumper wire between the terminal for the suspect circuit on the breakout T and Terminal 9 (Retarder Solenoid Common).
   • Terminal 11 (LOW/HI Retarder Solenoid)

   • Terminal 10 (MED/HI Retarder Solenoid)

5. Turn the key switch to the ON position.

6. Access the "Retarder Brake Test" in the "Special Tests" under the "Diagnostics" menu.

7. Start the test.

8. Check for active diagnostic codes that are related to the engine retarder.

9. Stop the test.

10. Check for active diagnostic codes that are related to the engine retarder.

Expected Result:

A "current high" diagnostic code (short circuit) is active when the jumper wire is in place and the "Retarder Brake Test" is active.

Note: A "current low" diagnostic code (open circuit) will be active when the jumper wire is removed and the test is not active.

Results:

• OK - There is a problem in the harness between the ECM and the valve cover base.

  Repair: Remove the breakout T and reconnect the J1/P1 ECM connector.Inspect the wiring between the ECM and the valve cover base.Disconnect the P300 connector.Insert a jumper wire between the terminal on the P300 connector for the suspect solenoid and chassis ground.Repeat this Test Step.If there is still a "current low" diagnostic code (open circuit), the problem is the supply wire.If there is a "current high" diagnostic code (short circuit), the problem is the common wire.Repair the wiring or replace the wiring.Verify that the repair eliminates the problem.

  STOP

• Not OK - There may be a problem with the ECM.

  Repair: Temporarily connect a test ECM.If the test ECM fixes the problem, reconnect the suspect ECM.If the problem returns, permanently replace the ECM.Verify that the repair eliminates the problem.

  STOP

Test Step 6. Create an Open Circuit at the Valve Cover

1. Disconnect the J300/P300 Injector connector on the valve cover base.

2. Access the "Retarder Brake Test" in the "Special Tests" under the "Diagnostics" menu.

3. Start the test.

4. Check for active diagnostic codes that are related to the engine retarder.

5. Stop the test.

6. Check for active diagnostic codes that are related to the engine retarder.

Expected Result:

A "current low" diagnostic code (open circuit) is active.

Results:

• OK - The harness between the ECM and the valve cover base is OK. Proceed to Test Step 7.

• Not OK - There is a problem between the valve cover base and the ECM. Proceed to Test Step 8.

Test Step 7. Create an Open Circuit at the Retarder Solenoids

1. Turn the key switch to the OFF position.

2. Remove the valve cover(s).

3. Disconnect the wires from each engine retarder solenoid. Ensure that the wires are not touching any metal parts.

4. Turn the key switch to the ON position.

5. Access the "Retarder Brake Test" in the "Special Tests" under the "Diagnostics" menu.

6. Start the test.

7. Check for active diagnostic codes that are related to the engine retarder.

8. Stop the test.

9. Check for active diagnostic codes that are related to the engine retarder.

Expected Result:

A "current low" diagnostic code (open circuit) is active.

Results:

• OK - There may be a problem with the engine retarder solenoid.

  Repair: Inspect the common wire for shorts. Repair any faulty wiring or replace any faulty wiring.Temporarily connect a new engine retarder solenoid.If the new solenoid fixes the problem, reconnect the suspect solenoid.If the problem returns, permanently replace the solenoid.Verify that the repair eliminates the problem.

  STOP

• Not OK - There is a problem in the harness under the valve cover.

  Repair: Inspect the wiring between the valve cover base and the engine retarder solenoids.Repair the wiring or replace the wiring.Verify that the repair eliminates the problem.

  STOP

Test Step 8. Create an Open Circuit at the ECM

1. Turn the key switch to the OFF position.

2. Disconnect the J2/P2 ECM connector.

3. Turn the key switch to the ON position.

4. Access the "Retarder Brake Test" in the "Special Tests" under the "Diagnostics" menu.

5. Start the test.

6. Check for active diagnostic codes that are related to the engine retarder.

7. Stop the test.

8. Check for active diagnostic codes that are related to the engine retarder.

Expected Result:

A "current low" diagnostic code (open circuit) is active.

Results:

• OK - There is a problem in the harness between the ECM and the valve cover base.

  Repair: Inspect the wiring between the ECM and the valve cover base.Repair the wiring or replace the wiring.Verify that the repair eliminates the problem.

  STOP

• Not OK - There may be a problem with the ECM.

  Repair: Temporarily connect a test ECM.If the test ECM fixes the problem, reconnect the suspect ECM.If the problem returns, permanently replace the ECM.Verify that the repair eliminates the problem.

  STOP

Test Step 9. Check the Status of the Engine Retarder Switch

1. Turn the key switch to the ON position.

2. Monitor the status for "Retarder Off/Low/Med/High Switch" on Cat ET.

3. Operate the engine retarder switch in the ON position and the OFF position. Also, operate the engine retarder switch in the Low, Medium, and High positions.

Expected Result:

The status for "Retarder Off/Low/Med/High Switch" correlates to the position of the engine retarder switch.

Results:

• OK - The engine retarder switch is operating correctly. Proceed to Test Step 11.

• Not OK - There is a problem in the circuit for the engine retarder switch.STOP

Test Step 10. Check the Switch Circuits at the Firewall Bulkhead Connector

1. Turn the key switch to the OFF position.

2. Disconnect the firewall bulkhead connector. Remove the three wires for the retarder off/low/medium/high switch from the firewall bulkhead connector.

3. Insert a jumper wire between the following wires on the vehicle harness:
   • AP Sensor/Switch Sensor Common

   • Retarder Solenoid Low/Hi Switch

4. Turn the key switch to ON position.

5. Check the status for "Retarder Off/Low/Med/High Switch" on Cat ET. Remove the jumper wire.

6. Turn the key switch to OFF position.

7. Insert a jumper wire between the following wires on the vehicle harness:
   • AP Sensor/Switch Sensor Common

   • Retarder Solenoid Med/Hi Switch

8. Turn the key switch to ON position.

9. Check the status for "Retarder Off/Low/Med/High Switch" on Cat ET.

Expected Result:

The status for "Retarder Off/Low/Med/High Switch" indicates "Low" when the common wire and the wire for the retarder low/high switch is jumped.

The status for "Retarder Off/Low/Med/High Switch" indicates "Medium" when the common wire and the wire for the retarder medium/high switch is jumped.

Results:

• OK - The status changed accordingly. There is a problem in the vehicle harness in the cab.

  Repair: Repair the harness or replace the harness in the cab.Reconnect all wires and connectors.Verify that the repair eliminates the problem.

  STOP

• Not OK - There is a problem between the ECM and the firewall bulkhead connector.

  Repair: Repair the harness or replace the harness between the ECM and the bulkhead connector.Reconnect all wires and connectors.Verify that the repair eliminates the problem.

  STOP

Test Step 11. Check the Operating Parameters of the Engine Retarder

1. Turn the key switch to the ON position.

2. Access the "Configuration" screen on Cat ET. Review the programming of the following parameters:
   • "Engine Retarder Mode"

   • "Engine Retarder Minimum VSL Type"

   • "Engine Retarder Minimum Vehicle Speed"

   • "Engine Retarder Delay"

3. Use the following information when the parameter for the "Engine Retarder Mode" is being reviewed:

   1. If the parameter is programmed to Latch mode or Coast mode, the engine retarder will not turn on unless the following conditions are met:
      • The Cruise Control On/Off Switch is on.

      • The service brake pedal has been depressed.

4. Use the following information when the parameter for the "Engine Retarder Minimum VSL Type" is being reviewed:

   1. This parameter has no effect on engine retarder operation when the "Engine Retarder Minimum Vehicle Speed" is programmed to 0 mph.

   2. When this parameter is programmed to the Hard Limit and the vehicle speed drops below the Engine Retarder Minimum Vehicle Speed, the engine retarder turns off.

   3. When this parameter is programmed to the Soft Limit and the vehicle speed drops below the Engine Retarder Minimum Vehicle Speed, the engine retarder remains in the ON position.

5. Use the following information when the parameter for the "Engine Retarder Minimum Vehicle Speed" is being reviewed:

   1. When the programmed value is more than 0 mph, the engine retarder will not turn on below the programmed value.

Note: The retarder will not turn on if the vehicle speed is already below the "Engine Retarder Minimum Vehicle Speed".

6. Use the following information when the parameter for the "Engine Retarder Delay" is being reviewed:

   1. This parameter provides a programmable delay once the conditions are met in order to turn the engine retarder.

Expected Result:

The problem is due to the programming of any of the listed parameters.

Results:

• OK -

  Repair: Perform the following diagnostic procedure:Program parameters for desired operation.Refer to Troubleshooting, "Customer Specified Parameters" for additional information on the listed parameters.

  STOP

• Not OK - The parameters are programmed correctly. Proceed to Test Step 12.

Test Step 12. Check the Accelerator Pedal

1. Turn the key switch to the ON position.

2. Monitor the status for "Accelerator Pedal Position" on Cat ET while the accelerator pedal is fully released.

3. While the status is monitored, depress the accelerator pedal.

Expected Result:

The status for "Accelerator Pedal Position" is less than 8% when the accelerator pedal is fully released. The status changes as the accelerator is depressed.

Results:

• OK - The accelerator pedal is operating correctly. Proceed to Test Step 13.

• Not OK - The accelerator pedal position sensor is not operating correctly.

  Repair: Refer to Troubleshooting, "Accelerator Pedal (Throttle) Position Sensor Circuit - Test".

  STOP

Test Step 13. Check the Clutch Switch

1. Turn the key switch to the ON position.

2. Monitor the status for "Clutch Pedal Position Switch" while the clutch pedal is fully released.

3. While the status is monitored, depress the clutch pedal.

Expected Result:

The status for "Clutch Pedal Position Switch" is "Off" when the clutch pedal is fully released. The status is "On" when the clutch pedal is depressed.

Note: If a clutch pedal is not installed, select "OK".

Results:

• OK - The clutch pedal position switch is operating correctly. There may be a mechanical problem with the engine retarder.

  Repair: Refer to Testing and Adjusting, "Compression Brake".

  STOP

• Not OK - The clutch pedal position switch is not operating correctly.

  Repair: Refer to Troubleshooting, "Clutch Pedal Position Switch Circuit - Test".

  STOP