Passport Electrical Issues
From Fozzee.net
My friend Seth from work drives a 2000 Honda Passport which, in those years, is the same thing as the Isuzu Rodeo. The other morning, he went to start it, and the battery was dead. He popped the hood and discovered the battery clamps in pretty sorry shape. He gave them a good scrubbing, and replaced the battery, but it still wouldn't start, and seemed to be mysteriously draining the battery.
Seth said that he suspected a short somewhere in the system, and planned on systematically pulling fuses until he "made the short go away". We did some digging online, and found that PDFTown had a set of schematics for a 1997 Passport which, it turns out, is very similar electrically. We were able to use these diagrams to devise a plan of attack. We worked our way through the fusebox under the hood, pulling each fuse, watching the resistance between ground (acquired off either the BAT- or the stud adjacent to the battery tray) and BAT+. We removed each fuse, fusible link, etc, and identified 3 fuses responsible for constant loads: ECU/ABS, and a single accessory fuse.
By this time, we figured we'd power the car back on, sans all the constant-load fuses, and replace them one at a time. As we replaced each fuse, the battery voltage didn't drop significantly. When a load was applied, however (headlights), the battery voltage dropped like a rock, from ~12.7 back to 9.8. I couldn't figure out how a brand new battery lost charge so fast (we'd had it sitting on the charger while debugging the fusebox). I removed the load (turned off the lights) and battery voltage didnt go up even a bit.
I had a flash that maybe the clamps were the problem after all. A reading from the + clamp to the + terminal in the fusebox revealed the problem: a resistance like 3k-ohms. We went promptly to the parts place to procure new brass battery post clamps. To make a long story short, the new clamps fixed the problem straight away. Seth is happy.
Below are some random photos of under the hood of the aforementioned 2000 Honda Passport.
