Our first vehicle in our Asian Buffet is a 2010 Honda Odyssey 3.5L, V6 came in with a complaint of a dead battery. The vehicle owner already had replaced the battery himself and still was experiencing a dead battery if the vehicle was not started twice a day.
The first order of business was to charge the battery marking sure we started our diagnosis with a fully charge. We followed this by checking the charging system that was working as designed. The next step to perform was a parasitic draw test that is done by installing a current clamp on the negative battery cable. As you can imagine, there had to be a large draw if the battery was being drained in less than one day. The amp clamp was reading 0.389 milliamps current draw, and that is way over the specification of 0.030 milliamps.
Our objective was to locate the circuit that was drawing the current. That turned out to be easier said than done. Our usual first step would be to perform a voltage drop test on all available fuses, followed by pulling fuses while observing the current draw on a meter. Because this Honda has a few power distribution boxes, we started with the easiest first — the one located under the hood.
Unfortunately, this testing did not yield the circuit that was killing the battery. The next place we tested was at the power distribution box located under the driver’s dash. There we hit pay dirt. When we pulled fuse 7 the current draw dropped to a normal level assuring us that we found the problem.
When we looked at the wiring diagram in MotoLOGIC, we learned that fuse 7 powered everything from power mirrors to the immobilizer, numbering more than a dozen potential culprits that could be causing the battery drain. We’ve been using thermal imaging as a diagnostic tool for a while now, and thought that would save us time going through the vehicle and unplugging each load. The thermal imager led us to the right rear side sliding door motor assembly (Figure 1) and the right rear body panel (Figure 2) was removed. At first we thought that the problem was just the right sliding door motor and latch assembly, but even with both disconnected we still had a current draw of 0.146 (Figure 3).
Because there was still a good size draw on the battery, we performed another scan with our thermal imager and located the last draw. Even with the door motor and latch unplugged, our thermal imager still showed a heat source (current flow) in the control module. Take notice of the yellow/lite color that indicated current draw even after the load (right side sliding door motor and latch) were removed. The fix for this vehicle was to install a new right side sliding door motor, latch and control module.