Diagnosing and resolving engine issues in your Mercruiser marine engine often involves understanding fault codes. These codes, triggered by various sensor readings and system checks, are crucial for pinpointing problems. Mercruiser engines, like many modern engines, categorize these faults into two main types: sticky and non-sticky. Knowing the difference and how to manage them, especially with a Cds Scan Tool For Mercruiser, is essential for effective maintenance and repair.
Sticky faults, once activated, remain active even if the underlying issue has been resolved. Think of it as a persistent reminder. Even if the sensor reading returns to normal or the circuit malfunction is fixed, the fault code will continue to display as active. To clear a sticky fault, a key switch cycle – turning the engine off and then back on – is required. This reset is necessary to tell the engine control module (ECM) to re-evaluate the system and clear the fault from its active status.
Non-sticky faults, on the other hand, are more dynamic. These faults can transition from active to inactive without requiring a key cycle. If a non-sticky fault condition corrects itself, the system will automatically update the fault status to inactive. This is useful for intermittent issues that might resolve spontaneously.
When using a cds scan tool for mercruiser, it’s important to understand how it displays these fault types. A CDS tool will continue to show sticky faults as active even after the problem is corrected, until a key cycle is performed. This is not a malfunction of the scan tool, but rather a reflection of how the Mercruiser ECM manages sticky faults. If you are struggling to clear a fault after addressing the apparent cause, remember to cycle the key to reset any sticky codes.
Beyond the standard key cycle, there’s an alternative method that might help clear sticky faults, particularly on models equipped with the “trim with key off” feature. This method involves placing the control handle in full reverse “Wide Open Throttle” (WOT) immediately after cycling the key switch. While not universally applicable, this technique can sometimes be effective in resetting persistent sticky faults.
It’s also worth noting that older Mercruiser engines utilizing MEFI-1 through MEFI-4 marine EFI systems had different diagnostic procedures. Tools like the CodeMate were used for these earlier systems. To clear codes on these older systems using a diagnostic code tool (non-scan type), a specific throttle procedure was used. This involved entering service mode on the code tool, turning the key ON, and then moving the throttle from 0% to 100% and back to 0% while in neutral. This method is distinct from the key cycle or WOT method used on newer systems and CDS scan tools.
Finally, a common issue that can interfere with fault code clearing is a poorly charged battery or engine cranking problems. A low battery can cause the ECM to reset improperly, preventing stored trouble codes from being cleared from the EEPROM memory. If you encounter difficulties clearing codes, ensure your battery is fully charged. A low battery condition may also be indicated by an audio warning buzzer sounding for 2 seconds after engine start-up.
In summary, when working with Mercruiser engine fault codes and using a cds scan tool for mercruiser, understanding the difference between sticky and non-sticky faults is crucial. Remember to use a key cycle to reset sticky faults, consider the alternative WOT method for certain models, and be aware of the different procedures for older MEFI systems. Always ensure a healthy battery for reliable diagnostics and fault code clearing.
