Electrical issues

[Spike555]

Hello everyone, new here but not to forums or 4x4's or wrenching.
I picked up a '04 one owner Land Cruiser this June after my old trusty Disco gave up the ghost after nearly a decade of faithful service.

I am having trouble with my underhood fuse box getting water in it and wrecking havoc.
I have scoured the web for a month, talked to a 20yrs Toyota Master Tech and even though this is a common problem there is zero info on the cause and how to fix it.
The master tech said to replace the windshield as it was prone to leaking in the lower left corner letting water onto the under dash fuse panel.
So I had that done, had the installer check for excessive rust, any signs of leakage, any clues at all. There was nothing.

I have since narrowed it down to the underhood fuse box, the truck can sit in a torenchial downpour for a week and have zero problems, but as soon as I drive it through a puddle in the road I have problems.
Here is what happens, the truck thinks the key is in the ignition (chipped key), the gauges on the instrument cluster will stay live, unless I turn the front and rear HVAC systems off before shutting the truck down the fans will stay on until the battery goes dead.
Also the alarm will go off at random, which the neighbors love at 2am. So I cannot lock it.
And the passenger headlight will flicker. If I hook up the battery charger while this is happening both headlights will come on and stay on as long as the charger is hooked up or until it decides its not going to act up anymore.
When it is acting up if I push on the backside (the side facing the firewall) of the fuse box the problem goes away. Let go and it starts again.
I replaced the battery and alternator just in case. Interstate battery, Denso alternator.

I am going to remove the fuse box this weekend and see if there is something obvious and I'm going to see how I can seal the fuse box.
A new fuse box is $650, a used one is $50 but I imagine a used one will do the same thing.
I am ready to trade the truck in for a Range Rover.
Any help would be greatly appreciated.

 

[Spike555]

I get the exact same response from the dealer and indie shop....nothing.
No one knows.

 

[toylandcruiser]

it actually isn't a common issue

 

[Spike555]

According to my literal month searching Google these electrical issues are common, the most common is a leaking windshield as the cause.
But the HVAC fan staying on, weird alarm issues etc. are common.
I am no LC expert, I'm just relaying what I've found. Every forum thread with this/similar issue is always finished with "I sold the truck" or nothing at all.
If no one has any ideas I understand.

 

[toylandcruiser]

According to my literal month searching Google these electrical issues are common, the most common is a leaking windshield as the cause.
But the HVAC fan staying on, weird alarm issues etc. are common.
I am no LC expert, I'm just relaying what I've found. Every forum thread with this/similar issue is always finished with "I sold the truck" or nothing at all.
If no one has any ideas I understand.

in my search on mud nothing popped up. on the truck i had it never happened.

 

[benjrblant]

This doesn't sound like a 'normal' problem to have on any vehicle. As the truck is new to you, do you have any details on the history? Any electrical mods or aftermarket alarms? I'm not too familiar with this issue specifically, but have you considered previous water damage or flooding of the vehicle?

...the truck can sit in a torenchial downpour for a week and have zero problems, but as soon as I drive it through a puddle in the road I have problems.

So applying water from the underside seems to be the issue. Possibly some bad seals, exposed wires, or cracked plastic?

Sorry to hear about your frustrations, hope this helps!

 

[Spike555]

This doesn't sound like a 'normal' problem to have on any vehicle. As the truck is new to you, do you have any details on the history? Any electrical mods or aftermarket alarms? I'm not too familiar with this issue specifically, but have you considered previous water damage or flooding of the vehicle?



So applying water from the underside seems to be the issue. Possibly some bad seals, exposed wires, or cracked plastic?

Sorry to hear about your frustrations, hope this helps!

Thank you for your reply. It had a remote car starter, I had it removed. I have removed and cleaned all electrical grounds under the hood. There are no exposed wires, cracked plastic or anything.
The seal on the underhood fuse box lid was dried and shrunken, I soaked it with silicon spray, it swelled up and I assume it is sealing. But the problem remains.
I have no recourse with the dealer as I bought it used with no warranty at the beginning of June 2016.
I agree it seems like a water getting in from below issue, but I am lost as to where the water is coming in from.
Any more suggestions are more than welcome.

 

[Spike555]

Saturday I unhooked the battery and opened up the underhood fuse box. I could not remove it completely but I was able to remove the bottom cover, it had a few bits of corrosion laying in the bottom of it.
I removed all of the relays on the top and sprayed with corrosion cleaner. Let it dry.
The three wire harness that went into the fuse box I wrapped in electrical tape and then used silicone to seal the openings where the wire harness enter the fuse box.
I put it all back together, it rained all day Sunday. I drove it around quite a bit Sunday and so far so good.
I'll run her through the carwash this weekend and see what happens and then if that turns out good I'll give the engine bay a wash to get all of the sand from the dunes out of it.