Inside 30 amp Fuse Blows shortly after power up (1 Viewer)

[jdefriel]

I have a 2000 LX470 and just this week the 30 amp fuse in the driver foot fuse box that controls the door lock actuators, sun roof, power seats, power windows, and power steering column adjustment blows a few seconds after powering on the car. That is a lot of systems to check the wiring. Anyone dealt with this before? Any common systems to start inspecting?

When I first replace the fuse and power up I can get all of the systems to work briefly and nothing seems to be acting unusual then it blows about 10-15 seconds after power up. If it was a short some system just wouldn’t function, right? If it was a motor acting up then it would likely start operating right away or be stuck in an on position or not work at all. Other than tracing all the wires and finding a location to disconnect each and every system I am at a loss. Any ideas appreciated.

 

[Mike NXP]

When you replace the fuse , you mentioned it works briefly and then pops after 10-15 seconds. Does a specific act make it pop , like moving the driver seat or sun roof? or does it just blow a fuse after 10-15 seconds without using any of the equipment on that circuit?

Maybe pinched wire in seat or lumbar, I think Ive seen some mention of that in the past on mud before

Any signs of wetness or corrosion at the fuse panel? Should be all dry and dusty down there

 

[jdefriel]

When you replace the fuse , you mentioned it works briefly and then pops after 10-15 seconds. Does a specific act make it pop , like moving the driver seat or sun roof? or does it just blow a fuse after 10-15 seconds without using any of the equipment on that circuit?

Maybe pinched wire in seat or lumbar, I think Ive seen some mention of that in the past on mud before

Any signs of wetness or corrosion at the fuse panel? Should be all dry and dusty down there

All dry down there. That is definitely a worry since it sits right below the firewall through hole.

I think it is the lumbar switch or wiring pinched somehow. It did seem to blow when I tested the lumbar but I didn’t know if that’s a coincidence. I took the cover off and disconnected the switch and was able to get readings on the ohmmeter between the ground and the two wires going to the motor which is acting like a short. I am waiting on more fuses to arrive in the mail so I can test it again. I already blew all the fuses available at my local O’Reilly’s.

 

[jdefriel]

All dry down there. That is definitely a worry since it sits right below the firewall through hole.

I think it is the lumbar switch or wiring pinched somehow. It did seem to blow when I tested the lumbar but I didn’t know if that’s a coincidence. I took the cover off and disconnected the switch and was able to get readings on the ohmmeter between the ground and the two wires going to the motor which is acting like a short. I am waiting on more fuses to arrive in the mail so I can test it again. I already blew all the fuses available at my local O’Reilly’s.

Got a new fuse and ram the system with the seat controls disconnected. Looks like a pinch in the lumbar wiring somewhere. I’ll have to remove the seat to confirm the exact location but glad to have narrowed it down from five systems feeding into one fuse.

 

[Mike NXP]

Got a new fuse and ram the system with the seat controls disconnected. Looks like a pinch in the lumbar wiring somewhere. I’ll have to remove the seat to confirm the exact location but glad to have narrowed it down from five systems feeding into one fuse.

You can try to get lucky and pop off the back seat panel. The lumbar circuit has a connector back there if I can remember right.

Gettin the back panel off can be a bitch and sometimes clips break. It requires some inward and upwards force to get it to pop out but youll probably end up needing to take it off anyway unless the problem is on the switch side

 

[Muskyfever]

Maybe pinched wire in seat or lumbar, I think Ive seen some mention of that in the past on mud before

You should work at NASA!! That was terrific!