87121-ZW3-000 Honda MARK, RR. (40) (Honda Code 4683504).

Table 1
Diagnostic Codes
CDL Code Code Description
(code descriptions may vary) Comments
791-5 Compression Brake Low/High Solenoid : Current Below Normal The code is logged.
791-6 Compression Brake Low/High Solenoid : Current Above Normal The code is logged.
792-5 Compression Brake Medium/High Solenoid : Current Below Normal The code is logged.
792-6 Compression Brake Medium/High Solenoid : Current Above Normal The code is logged. Perform this procedure under conditions that are identical to the conditions that exist when the problem occurs. Typically, problems with the compression brake solenoids occur when the engine is warmed up and/or when the engine is under vibration (heavy loads)."Compression Brake Solenoid Test"The "Compression Brake Solenoid Test" is a diagnostic test that is available on Caterpillar Electronic Technician (ET). Use the "Compression Brake Solenoid Test" to assist in troubleshooting problems in the circuit for the compression brake. The Electronic Control Module (ECM) will only detect shorts in the circuit for the compression brake 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 compression brake 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.Note: The engine speed must be zero before the "Compression Brake Solenoid Test" will function.
Illustration 1 g01199118
Location of the compression brake solenoid (typical example)
Illustration 2 g01290898
Schematic for the compression brake circuit
Test Step 1. Inspect the Electrical Connectors and the Wiring
Electrical shock hazard. The electronic unit injector system uses 90-120 volts.
Remove the electrical power from the engine's ECM. A strong electrical shock hazard is present if the electrical power is not removed from the engine ECM.
Illustration 3 g01290902
Left side engine view (typical example)
(1) J2/P2 ECM connectors
(2) J1/P1 ECM connectors
Illustration 4 g01239528
Left side engine view (typical example)
(4) Valve cover entry connector
Thoroughly inspect connectors (1) and (2). Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 5 g01141312
P2 ECM connector
(P2-1) Compression brake solenoid low/high
(P2-8) Compression brake solenoid med/high
(P2-14) Digital return
Illustration 6 g01195659
Valve cover entry connector
(10) Compression brake solenoid med/high
(11) Compression brake solenoid low/high
(12) Digital return
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with injector solenoids.
Check the allen head screw for each of the ECM connectors and the machine connectors for the proper torque. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasion and for pinch points from the valve cover back to the ECM. Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion, or of pinch points.Results:
OK - The harness and connectors appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem with the connectors and/or wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals for each of the connectors are properly in place and ensure that the connectors are completely coupled. Verify that the repair eliminates the problem.STOPTest Step 2. Check for Active Diagnostic Codes and/or Logged Diagnostic Codes
Connect Cat ET to the service tool connector.
Restore the electrical power to the ECM.
Access the "Special Tests" under the "Diagnostics" menu.
Start the "Compression Brake Solenoid Test" on Cat ET.
Once Cat ET displays the status of the compression brake solenoid, stop the "Compression Brake Solenoid Test".
Check for active diagnostic codes and/or logged diagnostic codes that are associated with the compression brake solenoids. Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic codes are active.Repair: If an intermittent problem is suspected refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - A low current diagnostic code (05) is active at this time. Proceed to Test Step 3.
Not OK - A high current diagnostic code (06) is logged at this time. Proceed to Test Step 5.Test Step 3. Short the Wires of the Suspect Compression Brake Solenoid at the Valve Cover Connector
Remove the electrical power from the ECM.
Disconnect the valve cover connector for the suspect compression brake solenoid.
Fabricate a jumper wire in order to create a short between the supply and the return for the suspect compression brake solenoid.
Restore the electrical power to the ECM.
Access the "Special Te