Weird Electrical Issue

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Mar 23, 2023 | 03:25 PM

lukeaj

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3rd Gear

Joined: Mar 2023

Posts: 3

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From: Upstate NY

Weird Electrical Issue

Have a weird electrical issue that I need some advice on what it could be. Whenever I try start the truck, I blow the 20amp maxi fuse #10 in the engine compartment fuse box. It is labeled as "Instrument panel fuses: 15,18, Starter relay coil". If I unplug the starter relay, it still blows. If I pull fuse 15 and 18 and turn over to start it won't blow. When I put in fuse 18 and have the start relay and 15 pulled, it will still blow. Now, if I have both fuses and starter relay connected and I just put the key to ignition on, I can manually trigger the starter relay and it starts and runs fine.

Looking for any ideas what could cause this.

Mar 23, 2023 | 04:05 PM

knottyrope

Lead Driver

Joined: Apr 2016

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From: Bahstun

think your starter relay coil is bad next to battery on pass side or maybe the wire to it is shorted to frame

Mar 23, 2023 | 04:47 PM

lukeaj

Thread Starter

3rd Gear

Joined: Mar 2023

Posts: 3

Likes: 0

From: Upstate NY

Quote:

Originally Posted by knottyrope

think your starter relay coil is bad next to battery on pass side or maybe the wire to it is shorted to frame

I thought that a first too, but if I pull only fuse 18 inside the instrument panel (which is a 10 amp fuse for Brake shift interlock, Speedometer, Selectable RPM control (Diesel), Speed control (Diesel)) it starts right up and doesn't blow the fuse. After the truck is started I can throw it right back in. Only moving the key to the start position with fuse 18 in blows the 20 amp in the engine compartment.

Last edited by lukeaj; Mar 23, 2023 at 04:48 PM. Reason: more information.

Mar 23, 2023 | 05:50 PM

lukeaj

Thread Starter

3rd Gear

Joined: Mar 2023

Posts: 3

Likes: 0

From: Upstate NY

Found it I think. My brake shift interlock is broke. Rather than getting stuck not being able to shift, I can shift without pressing the brake. For some reason it is blowing the engine compartment fuse rather than the instrument panel fuse... and only when going to start the car... just enough extra drain on the whole circuit? Going to try replacing it and see if that fixes the issue.