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Toyota Service
Toyota Service, Toyota Expert
Category: Toyota
Satisfied Customers: 4848
Experience:  30+ Yrs of auto experience, Award Winning Svc. Manager; Just Answer Customer's Choice Award Winner
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I have 2003 4runner and when it rained 3 days water leaked

Customer Question

I have 2003 4runner and when it rained 3 days water leaked into flioorboards.then without any key in ignition the car in middle of night was cranking by self but not sta r ting.i had to unplug battery terminal. Now I go to start it and won't crank.we checked and dried fuses and crossed starter to see if was starter and wasnt.any ideas
Submitted: 1 year ago.
Category: Toyota
Expert:  Toyota Service replied 1 year ago.

Hello. Welcome to Just Answer. Please allow me to assist you. Any time the car cranks by itself after a heavy rain (or other things activate that should not have activated without user input), the most likely problem is water leaking onto a critical electronic device under the dashboard called the 'integration relay'. This is not a realy in the normal sense of relays, it is more of a power distribution center. Inside this unit, there are thin wires that transfer power to and from the fuse panel. When the water gets onto these thin wires (they are not insulated), the water will cause corrosion. Eventually, the corrosion will build up on the exterior of the wires, and the corrosion will touch another wire. This allows the transfer of a powered wire into a circuit that is normally switched (like the starter). This causes the power from one wire to 'jump' into the other wire, thusly activating that particular circuit. The recommendation I have for you is to first identify the source of the water entry. This could be via a leaking windshield, sunroof, poor body repair, poor cowl panel sealing, etc. Once the water leak ahs been identified and rectified, then remove the fuse panel and locate the integration relay. It connects to the fuse panel. Using the 10 digit part number on the box, order an exact duplicate form a Toyota parts department. Note that the fuse box removal to access the integration relay is a rather involved process, (difficult) and is not recommended for owners who are not skilled in dashboard disassembly. It takes a good Toyota tech about 2 hours to do this job. If you are not skilled in this procedure, leave this one to the professionals. If the fuse panel is found to be soaked with water, I would replace the fuse panel also.

Expert:  Toyota Service replied 1 year ago.

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