Check and Clear ThunderMax Diagnostic Trouble Codes (DTCs)
Diagnostic Trouble Codes (DTCs) identify component faults detected by the ThunderMax ECM. Current codes report active faults; Historic codes report past faults. A set code does not itself indicate an ECM fault. Sensors, wiring and mechanical problems can set codes.
View / Download the Check and Clear DTCs Guide — PDF
Watch the Reading DTC video
Use the accompanying TMax Tech Tips video as a visual reference. It also covers checking and clearing codes through the motorcycle speedometer.
Watch “Reading DTC — TMax Tech Tips”
Step 1: Access Diagnostic Codes
Open the ThunderMax software and link to the module. Expand Module Configuration, then select Diagnostic Codes.
Module Configuration > Diagnostic Codes.
The Trouble Codes dialog has four tabbed pages. Select each tab to view the other diagnostic codes.
Step 2: Check Current Faults
The left column reports currently faulting components. A number that has a count or is counting identifies a current failure.
Red: Current Fault / Yellow: Historic Fault. The Clear Diagnostic Codes button is circled in blue.
Step 3: Check Historic Faults
The right column reports past faults that were intermittent or have corrected themselves. If not accompanied by a current fault, historic faults may be cleared. Investigate any fault that returns after further operation.
Important: Correct currently failing components before further operation of the motorcycle. If Current Fault counts reappear after clearing, investigate and correct the cause.
Step 4: Clear diagnostic codes
Select Clear Diagnostic Codes at the bottom of the dialog.
Alternative: motorcycle speedometer
Codes can also be checked and cleared through the speedometer following Harley-Davidson® instructions. The Reading DTC tutorial covers this method.
Need help checking diagnostic codes?
Contact ThunderMax technical support or email support@thunder-max.com with any questions.
Based on the ThunderMax “Check and Clear DTCs” guide, version 0.3, dated October 27, 2026.
