A 2001 Honda Odyssey was brought into the shop with two problems to diagnose that you might not think would be related. The battery kept going dead, and the left sliding door wouldn’t open. I decided to focus on just the battery issue first.
I went through standard parasitic draw diagnostics, starting by putting an amp meter clamp around the negative battery cable to see how much of a draw there was. I then started pulling each fuse in the under-hood fuse box to see which one caused the draw to go away. Once I did, I followed the wiring diagram to the passenger interior fuse box, where the under-hood fuse fed four or five interior fuses. I did the same procedure there, and found that the fuse for the fuel door switch was causing the draw.
Reading the wiring diagram, I figured out that the fuel door has a switch that turns on a relay whenever the fuel door is open, which in turn prevents the left sliding door from opening. This is because the sliding door could catch on the open fuel door and cause damage. I removed some interior panels to find where the fuel door switch plugged in, and when I unplugged it, the draw on the battery was gone. With it unplugged, the relay was no longer turning on, which is what was draining the battery and preventing the sliding door from opening.
Despite the van being 20 years old, we were able to get a new switch put in, and I thought I was done with it, but when the customer came to pick it up, the battery was dead again. When I diagnosed it a second time, I found that the left sliding door rear latch was not properly closing, and was causing this new draw on the battery. I replaced the latch, and the car was finally fixed.
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