309S87301-1 Tohatsu LOWER UNIT ASSY

Table 1
Diagnostic Trouble Codes for ARD Combustion Supply Air Pressure Is Low
J1939 Code Code Description Comments
3837-17 Aftertreatment #1 Secondary Air Pressure : Low - least severe The air pressure that is supplied to the ARD falls below a minimum acceptable value that is calculated by the ECM.
One or more of the following codes will usually be present:
102-18
3473-31
3474-31
3711-31
The diagnostic code will be reset when a successful regeneration has occurred or the fault has been rest by the electronic service tool.
Illustration 1 g01994613
Components of the ARD combustion air supply
The combustion air valve (3) receives operating voltage from the engine ECM. The combustion air valve sends a position signal to the engine ECM. An ARD air pressure sensor (1) sends a pressure signal to the engine ECM. The ECM uses the pressure signal to determine the volume of combustion air that is being provided to the combustion air valve. The ECM controls the position of the combustion air valve in order to provide the correct volume of combustion air to the ARD.Test Step 1. Check for Associated Diagnostic Trouble Codes
Download the following items before performing any troubleshooting or clearing any diagnostic codes:
Warranty Report
Aftertreatment Regeneration Trigger History
Product Status Report with Histograms
Use the electronic service tool to check for active diagnostic codes. Table 2 lists the diagnostic trouble codes that are associated with a 3837-17 code. Determine if a code in Table 2 is present.
Table 2
Associated Diagnostic Trouble Code
Suspect Parameter Number (SPN) Failure Mode Identifier (FMI)
102 18
3473 31
3474 31
3711 31 Results:
An associated diagnostic trouble code is not present. - Proceed to Test Step 2.
An associated diagnostic trouble code is present. - Repair: Troubleshoot the associated code. Refer to Troubleshooting, "Diagnostic Trouble Codes".STOPTest Step 2. Inspect the Piping Between the High Pressure Turbocharger and the Combustion Air Valve
Inspect the piping between the high-pressure turbocharger and the combustion air valve.
Check for cracks in the piping.
Check for loose joints or damaged joints. Expected Result:The piping is damaged or cracked.Results:
The piping is damaged or cracked. - Repair: Replace the piping or repair the piping.Proceed to Test Step 4.
The piping is not damaged or cracked. - Proceed to Test Step 3.Test Step 3. Inspect the Piping from the Combustion Air Valve to the Pressure Sensor
Inspect the piping (2) from the combustion air valve to the pressure sensor.
Check for cracks in the piping.
Check for air leaks.
Check the clamps on the piping. Make sure that the clamps are tight. Results:
The piping is damaged or cracked. - Repair: Replace the piping or repair the piping.Proceed to Test Step 4.
The piping is not damaged. - Proceed to Test Step 4.Test Step 4. Perform the "ARD Air System Service Test"Use the electronic service tool to perform the ARD Air System Service Test.Results:
The ARD Air System Service Test is successful. - Repair: Use the electronic service tool in order to perform a "manual regeneration" and return the unit to service.STOP
The ARD Air System Service Test did not complete successfully. - The combustion air valve is faulty.Repair: Perform the following repair:
Replace the combustion air valve. Refer to Disassembly and Assembly, "Air Control Valve - Remove and Install".
Repeat this Test Step in order to confirm that the fault has been eliminated.
If the fault is still present, contact the Technical Communicator at a Caterpillar dealer. STOP