Tech Tips Online

June 17, 2002

Speedometer Signal and Code P0505
The speedometer signal is an extremely important input for the Delphi fuel
injection system. The ECM monitors throttle position and speed signal inputs in
order to properly maintain the set idle speed. If the ECM loses the speed signal
for any reason while the throttle is closed, the ECM assumes the vehicle is
stopped and will adjust the idle air control counts to bring engine rpm to the set
idle speed. This could set a P0505 code and adversely affect engine idle.


Source: http://www.harleyhog.co.uk/