LS180 Blowing Key Switch Fuse

[mfyock]

I have an LS180 that started acting up. I went to start it and it would crank over, but wouldnt fire. It sounded odd when cranking(sounded different), but cant explain what it was. It didnt even try to fire. I cracked an injector line to see if I was getting fuel. I go in to crank it, and now it wont crank. No solenoid click, nothing. After investigating I find there is a 5 amp fuse in the operators compartment blown, and the main 15 amp key switch fuse in the engine compartment is blown. I swap a fuse in the 15 AMP spot, and the machine cranks over, but blows the fuse again. I checked out the service manual, and there really isnt anything for troubleshooting the key switch fuse. Since this is on the "control" side, the only loads are the relays right? Could I have a bad relay?

 

[Tazza]

I wonder if the fuse that is blowing is the hold coil on the engine. When its working, it allows fuel to flow from theinjector pump, when it fails or is turned off, no fuel comes out so the engine will not start. Is it possible this is the problem?

 

[Mike10]

The 15a fuse protects the wire going to the key switch. When the switch is activated power is sent to the EIC, and to two terminals of the start interlock relay. The control voltage to this relay comes directly from the switch. The terminal of this relay that supplies power to the fuel shutoff solenoid, when the relay is energized, comes from the switch and goes through the 5a fuse you said was blown. You probably need to check the harness for shorts. The harness goes under the left fender so be sure to check that area also.