I was having weird electrical issues on my '04 LC, water was getting into the underhood fuse box.
I thought I had solved the problem but then it came back.
Until I opened up the fuse box, I removed the bottom tray, removed all of the relays and fuses. Sprayed electrical contact/corrosion inhibitor onto the fuse and relay sockets.
Let it dry, the stuff I used foams, dries clean. I repeated this a few more times.
Then I took a look at where the wire harness go into the fuse box, there are three points of entry.
The wire bundles are wrapped in a foam padding and that zip tied onto them to hold everything together.
The foam forms the seal to prevent water ingress.
So I took RTV and sealed the cut outs for the wire harness, all three of them.
Then put it all back together, reconnected the battery and drove for a week.
Then hit the full service carwash with undercarriage wash, no issues.
Then a week after that I took the garden hose and washed the whole engine bay, including the underhood fuse box.
Zero problems. Zero. It has been two weeks since doing this and I have driven around in the rain for a week, still no issues.
So, I am calling this one 100% solved.
The issues I was having are the HVAC fans were staying on all the time, the instrument cluster was staying live all the time, including the OD. The alarm would go off at random if the doors were locked. The truck thought the key was in the ignition even when it wasn't.
I replaced relays under the hood, had the windshield replaced, was shopping for a replacement truck as I was fed up with this one, replaced alternator and battery.
But it is the cleaning and resealing of the fuse box that solved the problem.
I thought I had solved the problem but then it came back.
Until I opened up the fuse box, I removed the bottom tray, removed all of the relays and fuses. Sprayed electrical contact/corrosion inhibitor onto the fuse and relay sockets.
Let it dry, the stuff I used foams, dries clean. I repeated this a few more times.
Then I took a look at where the wire harness go into the fuse box, there are three points of entry.
The wire bundles are wrapped in a foam padding and that zip tied onto them to hold everything together.
The foam forms the seal to prevent water ingress.
So I took RTV and sealed the cut outs for the wire harness, all three of them.
Then put it all back together, reconnected the battery and drove for a week.
Then hit the full service carwash with undercarriage wash, no issues.
Then a week after that I took the garden hose and washed the whole engine bay, including the underhood fuse box.
Zero problems. Zero. It has been two weeks since doing this and I have driven around in the rain for a week, still no issues.
So, I am calling this one 100% solved.
The issues I was having are the HVAC fans were staying on all the time, the instrument cluster was staying live all the time, including the OD. The alarm would go off at random if the doors were locked. The truck thought the key was in the ignition even when it wasn't.
I replaced relays under the hood, had the windshield replaced, was shopping for a replacement truck as I was fed up with this one, replaced alternator and battery.
But it is the cleaning and resealing of the fuse box that solved the problem.
