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Skyvisions, ASE Certified Technician
Category: Toyota
Satisfied Customers: 14412
Experience:  Toyota Master Diagnostic
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Toyota Lexus LS400: Hello again. I just replaced the front

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Hello again. I just replaced the front headlamp drivers side main beam. After I replaced the battery, the car did not receive back any power at all. The main fuse appears to be have no power. when I turn the ignition key--nothing. Any ideas of what could have gone wrong? One stupid thing I did was to leave the ignition key in the on position when I pulled the battery so it was still in on position when I re- hooked up the power. Is there a system reset button somewhere?
Thank you for choosing JustAnswer and allowing me to help you resolve your Toyota questions! There is no system reboot or reset. Having the key in the on position itself should not have caused the problem. At any time was the battery cable installed backwards or perhaps charged backwards?
Customer: replied 3 years ago.

No, the battery is showing a full charge, and my charger goes crazy when you try to cross charge it. Because the pos cable is connected to the battery cover, you can't hook up the battery backwards. I tested the power at the cables next to the battery and they are showing 12.25 volts. I will say that lately the connection with the gearshift has been a little loose in that you have to push it sometimes to get a power connection.

Am not sure where to go with this one. You're going to have to check for power at all of the fuses and double check your connections at the battery cable ends.
Customer: replied 3 years ago.

Ok I just discovered the main fuse panel under the hood behind the battery! I was testing the small fuse panel inside the car on the drivers side. I notice there is a line of fuses on the left side of the panel, and one says "main" and is 80A. It does not appear to be blown, but I tried to lift it out, and it doesn't want to come, so I guess it removes some other way. I thought I would test the pins to that fuse to see if power is getting to the "main". Any other suggestions of what to test on this fuse box to see if power is getting to it?

That 80 amp fuse is bolted into the fuse box do not tug on it to hard or you will break it. If you pop the plastic cap off the top and touched the copper band with your test light it should have 12 V if it does this means the main battery box or fuse panel is receiving 12 V from the battery. Are you 100% certain that the connections to the battery are not corroded or loose?
Customer: replied 3 years ago.

Ok I took off the connectors to the battery, and they were slightly corroded and I sanded and wire brushed everything. I tested the main fuse again and nothing. In fact I tested the input wire to the fuse block, and it is dead as well. Is there a connector under the engine as the main pos wire from the battery goes down there, and then the wire to the fuse block comes back up. Somewhere in between the wire leaving the battery with power and the wire coming into the fuse block there appears to be a break.

The main battery positive cable goes down to the starter. It breaks off of the main battery harness and goes up to the junction block. Make sure there's no corrosion down inside the main wire coming off of the battery cable and itself.
Customer: replied 3 years ago.

If I have to replace a wire, do you know what gauge it should be?

The one going down to the starter is a 1 gage or 0 gage.
Customer: replied 3 years ago.

and the one coming back up to the panel? I guess I should jack up the car and test the lead to the starter and see if that is live first? I wonder if I should put a lead from the positive side of the battery to the panel feed point and see if that energizes the car?

The wire going up to the fuse block is about a two or 3gauge. I would try jumper wire to the 80 amp fuse from the positive battery terminal and see if it energizes the systems in the car.
Customer: replied 3 years ago.

Yes I jumped a main wire from battery pos post to the feed post on the fuse block, and that solved the problem. Thanks for your help!

You are welcome. Glad to help.
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