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Juan Crespo
Juan Crespo, Tech Trainer
Category: Toyota
Satisfied Customers: 1500
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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I keep blowing fuses in my 2000 tundra tail light circuit.

Customer Question

I keep blowing fuses in my 2000 tundra tail light circuit. I've changed the combination switch. Removed all the bulbs. Removed the trailer light converter. Still shorts
JA: Sometimes things that you think will be really complicated end up being easy to fix with Toyota. The Toyota Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so he can help you best.
Customer: the 15amp tail light fuse keeps blowing. I've done all kinds of troubleshooting. The most troublesome is that I bought an ECT2000 tool that is supposed to find short circuits and it indicates there is not one. But when I turn on the circuit, it blows the fuse
JA: Are you hoping to fix this yourself?
Customer: I hope to - but at this point, I'll do anything to get it fixed
JA: Is there anything else the Toyota Mechanic should be aware of about your Toyota?
Customer: I need it to tow so I need a trailer converter that works, but I've disabled the one in there since what I've read they've problematic on this year truck
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Toyota Mechanic about your situation and then connect you two.
Submitted: 5 months ago.
Category: Toyota
Expert:  Juan Crespo replied 5 months ago.
Hi there.The only way to trace these shorts is by gradually eliminating portions of the affected circuit, which might include removing multiple components. Do you have an Ohmmeter and are comfortable using it to test circuit continuity to ground?.
Customer: replied 5 months ago.
I am. Are you familiar with tools to discover short circuits? I bought one and the answer confuses me. It shows that I don't even have a short - but I blow the fuse every time
Expert:  Juan Crespo replied 5 months ago.
I'm not familiar with that tool at all.First thing you need to do is perform a thorough visual inspection of all lamps and accessible connectors and wiring that are part of the license plate/marker/parking/tail lamp circuit - no sense in letting low hanging fruit go to waste.If the visual inspection does not reveal the problem, then you'll need to start to divide the circuit into sections. Are you comfortable following wiring diagrams? If so, I could upload one showing all the connections, junctions and splices...
Customer: replied 5 months ago.
I am. And in my troubleshooting, I've removed all the tail light and license plate bulbs from the circuit and tried it and it didn't fix it. I also isolated the dash lights and it didn't stop it from blowing. A diagram would help.
Expert:  Juan Crespo replied 5 months ago.
OK. Please give me a few minutes to locate and upload the diagram. Be back in a bit...
Expert:  Juan Crespo replied 5 months ago.
Sorry, forgot to ask what trim level Tundra are you working on? Access Cab? Regular Cab? LTD? SR5? 2 or 4WD? Engine size?
Customer: replied 5 months ago.
SR5 Access Cab - 4WD
Expert:  Juan Crespo replied 5 months ago.
Here we are.With all the bulbs removed to eliminate any type of false continuity, let's start by removing the fuse and placing the Ohmmeter Red probe on the vacant fuse cavity that's connected to the circuit (BE CAREFUL not to place it on the vacant fuse cavity that is connected to the battery!). Place the meter Black probe on the battery negative post - at this point, meter should show some resistance indicating continuity.Next, locate the junction or connector farthest in the circuit from the fuse and disconnect it. Check meter. If resistance still shown, continue on to the next farthest connection. Repeat until meter shows infinite resistance or open circuit identifying the short. Trace and repair/replace as needed.Please let me know what you find or if you need any assistance with this task.Best Regards.
Customer: replied 5 months ago.
I'll give it a try
Expert:  Juan Crespo replied 5 months ago.
Please notice the diagram has been configured with current flowing from power source at the top to grounds at the bottom. This is not how the actual circuit will look like. Use location legends to find component on the truck.Best Regards.
Expert:  Juan Crespo replied 5 months ago.
here is the original version from Toyota.