1998 Johnson Evinrude "EC" 150, 175 FFI Service Manual, P/N 520211, Page 90Get this manual
Step 5: Turn on the boat key switchThis will supply power to the ECUKey switch must remain ON throughout testStep 6: Wait 10 secondsIf the TP sensor is moved from its maximum limit before 10 seconds has expired, the ECU will not go into diagnostic modeIf this occurs, repeat the procedure starting at Step to re-enter diagnostic mode INote Step must be followed to ensure the ECU
has powered downThis requires either waiting minimum of 10 minutes, or shutting off ECU B+ currentIf either ofthese does not occur, the diagnostic mode cannot be re-entered
Step 7: Read and make note of the service codes, then determine which ones are Hard Codes so they can be diagnosed firstDo this by clearing all present codes and attempting to run the engineThen repeat Steps through and read the codes againThese final codes will be Hard CodesSee Service Code Chart for code interpretationTo Manually Erase Service Codes To manually erase service codes, perform the following Steps in the sequence shownThis procedure will erase ALL codes as they cannot be erased individuallyStep 1: While in the diagnostic mode, return the throttle position sensor to the low-end limit of its travel (idle position)Wait for seconds or moreThe "Check Engine" light will stay on during this timeStep 2: Move TP sensor again to its high-end limit (the "Check Engine" light will turn off)Then return the sensor to the low-end limit (the "Check Engine" light will turn on)