Fog Lights Fuse: Check My Logic

[MFMauceri]

With both front fog lights disconnected, my 20A fuse keeps blowing upon switching on lights at multifunction switch at steering column.

The hi beams are NOT engaged. Assuming the problem is somewhere between the switch and the fuse/relay block. Usual suspect: Twist/pull switch mechanism?... But NOT the relay?

 

[dbbd1]

I would start at the MFS.

 

[LONGJP2]

With both front fog lights disconnected, my 20A fuse keeps blowing upon switching on lights at multifunction switch at steering column.

The hi beams are NOT engaged. Assuming the problem is somewhere between the switch and the fuse/relay block. Usual suspect: Twist/pull switch mechanism?... But NOT the relay?

Yes, the MFS can cause various issues including blowing that fuse.
Does it also blow with the relay pulled out?

 

[MFMauceri]

Yes, the MFS can cause various issues.
Does it also blow with the relay pulled out?

Haven't, but will. If yes?..

If no?..

 

[LONGJP2]

Haven't, but will. If yes?..

If no?..

If yes, it eliminates the relay and moves the issue upstream.

 

[Coadster32]

If No, replace the relay.

 

[LONGJP2]

If No, replace the relay.

Sure (or check by swapping); or the problem is downstream.

Just to be clear, the fuse only blows when turning on the fog lights?
And they're currently disconnected?

 

[MFMauceri]

Sure (or check by swapping); or the problem is downstream.

Just to be clear, the fuse only blows when turning on the fog lights?
And they're currently disconnected?

Yes, disconnected. Fuse blows whether lamps are connected or not. When connected, lamps illuminate for a moment before fuse blows. Checked continuity from fuse block to each lamp, OK. Have to check diagram to see if relay is upstream or downstream from fuse (probably up). However, relay's sole purpose is to kill fog lights when hi-beams are engaged (so low chance that that's it). The relay pulls in the headlight circuit so it's a mess of pins at the connector(s).

 

[LONGJP2]

Yes, disconnected. Fuse blows whether lamps are connected or not. When connected, lamps illuminate for a moment before fuse blows. Checked continuity from fuse block to each lamp, OK. Have to check diagram to see if relay is upstream or downstream from fuse (probably up). However, relay's sole purpose is to kill fog lights when hi-beams are engaged (so low chance that that's it). The relay pulls in the headlight circuit so it's a mess of pins at the connector(s).

Sounds like you have a short to ground somewhere.
You'll need to visually inspect the wires for damage.