Expert: Roland Finston - 11/13/2011

Question
fuse #8 blows sometimes and sometimes not. More so when its colder and it is becoming more frequent. Cannot get it to do it for 2 days now?

Answer
Hi John,
Fuse #8 has a very large number of purposes, unfortunately. It powers the starter motor relay and solenoid switch at the starter motor, the fuel pump relay and fuel pump, transmission control module, radiator fan relays, ac compressor clutch, instrument cluster, skim, anti-lock brake controller, powertrain controller, radio, multi-function switch, airbag control module.
All on 20 amps! The best way to diagnose the cause is to figure out whether it is blowing when you first turn the key to the 'run' position (stop before going to the 'start' position) and listen to see if you hear the fuel pump run for about 1 second coming from the rear of the vehicle or not. If not then you would know that it is not the starter circuit. If the fuel pump doesn't run for a second then it blew immediately when you got to 'run' and we would have to sort out what of all those items was overdrawing the fuse. If instead it blows when you try the 'start' (no response from the starter, fuse found blown) then we have to check out the starting circuit. So first lets sort out which of those key positions the fuse blows out. I assume that the fuse doesn't blow once the engine is started and running, correct?
Roland