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Greetings to all,
I’m reposting this in case I put it in the wrong category at first, but I have a 2010 Honda Pilot Touring and my battery is being drained. I’ve performed a parasitic draw test as demonstrated by ETCG and, unless I’m missing one, I’ve pulled every fuse in the 4 fuse boxes. The draw was right around 2.58 amps through the entire test. I then disconnected the radio thinking the auto-theft feature was producing the draw. In the end, I took the car to the dealer b/c the battery is replaced for free, which they did after draining it. I was told their test should have found a short.
Here I am, two days after a new battery, with jumper cables and only 9 Amps on the battery. I can’t believe it’s a bad battery. I believe there is a short, particularly in the rear dome light. It has been acting funny lately, and since it’s a push-to-on type light, I can’t know if it’s on, or on when the door is open. So, I removed the fixture from the hood liner. While at work, I turned the dome lights “off” completely to see if there’s a drain.
Question is, apart from a parasitic draw test, how can I find a short in the electrical system. Esp if there is some sort of feature in the vehicle, like auto-theft, that makes a continuous draw on the battery thus making the draw test useless? Is there a better type of shop to go to for a diagnosis and discovery other than the dealership?
Thanks in advance!
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There is a problem doing parasitic draw tests on modern vehicles! Some of the draws are on timers that will take 5 minutes or so to time out and reach the off state current draw of about 40-80ma. Redo your tests and don’t forget the alternator may be directly connected to the battery. I have attached a link to a site where you can get a power distribution diagram for your vehicle. You may also consider getting a scan with an advanced scan tool that can check DTC’s that don’t set the MIL.
Another issue with modern cars is that pulling a fuse may cause a number of modules to wake up. This has caused a change in how to do a parasitic draw test, now the voltage drop is measured across the fuses. See this video by Humble Mechanic:
Have you ruled out a charging issue? Try measuring the battery voltage while the car is running- it should be over 13.5V
With a two day old battery in the car, would a charging issue drain the battery while the vehicle is parked for 9 hours?
If you drove it for any amount to time without a working charging system it would very quickly drain your battery leaving you without enough to start it next time you attempt to drive it.
Thanks to everyone for chiming in! Due to time constraints and needing to get kids to school, I went to my dealer for a diagnostic test. My dome light did have a short in the switch but that wasn’t the issue. Turned out to be the A/C clutch relay. I’m not sure I’d have figured that out but hope it’s done for. Sure learned a lot though. Really appreciate the community here to bounce stuff off of!
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