acsak
Well-Known Member
Would love to revive this thread. I'm tearing my hair out trying to find a battery drain.
TLDR:
I COULD USE YOUR HELP:
I must be missing something regarding the design of these switches. I always test the leads before testing for continuity. I’m using a new Fluke multimeter with new leads, both in excellent condition, and am an advanced hobbyist when it comes to electrical testing/circuit design/etc. It seems unlikely that both switches have no continuity since there’s no issues with ESS and no erratic hood ajar indications on EVIC.
Read below if it’s helpful to learn more about anything I’ve mentioned above.
DEEPER DIVE:
WORKING THEORY:
A variable which I'm looking into is the hood ajar switches. There are two near the driver side headlight. As I understand it, the inner switch (switch 1) simply tells the BCM and then the driver, via the EVIC, that the hood is open, and the outer switch (switch 2 - closer to the fender) is used to determine the hood position for ESS and Remote Start. ESS/Remote Start won't work if switch 2 is telling the PCM that the hood is open.
I realized this evening after two days of testing I never taped down those switches and since the hood has been open all this time, they've both been in the "open" position. After 1+ hour after ignition off and the Fluke reading ~17-40mA I decided to work each of these switches manually. The inner switch had no effect. The outer switch, however, woke something up. Depressing it causes a sudden draw of 4 amps which dies down to around 110mA after less than a minute. Interestingly, if I keep the switch depressed, wait for 110mA, and then release the switch, the current draw ALSO jumps up to 4 amps and follows the same pattern dropping down to 110mA.
I pulled both of those switches to test for continuity and to see if one of them has an intermittent connection. In theory this COULD explain the parasitic draw. Switching from either state to the other wakes up one of the logic modules, so an intermittent switch could be causing this several times throughout the night. A 4 amp draw multiple times overnight could definitely drain the main battery down to ≤12.2 volts.
They seem like straightforward switches. Two pins and a plunger switch connecting them. Thing is though - I couldn't get continuity across those pins in the open OR closed positions on BOTH switches. They are pretty dusty and dirty because of where they’re located, but I’ve never had an ESS issue since replacing the aux battery, and I don’t get intermittent “hood open” messages or anything like that.
DUAL BATTERY SETUP:
I have a rudimentary aftermarket dual battery setup. I used the Genesis DIY kit WITHOUT their electronics, though I am using the two group 25 Odyssey batteries that they sell. I already had a Redarc Smart Battery Isolator laying around and am using that to fully disconnect the aux battery at shutdown. This was a precautionary measure in case the main battery ever had a parasitic draw and it has turned out to be quite useful since the draw started. This worked just fine for many months. Main battery voltage was showing 12.5-12.7 on EVIC right before start up and, crucially, BEFORE I manually engage the Redarc solenoid and add the aux battery to the system. (I always check both batteries before connecting them and before starting the engine.)
THE PROBLEM:
For the past 6 months or so, however, the main battery always drains to 12.1-12.2 volts overnight. It very rarely goes to 12.0 volts and it absolutely never goes below that which suggests to me that something intelligent is causing the drain - something that has a built in low voltage cutoff. I've never had a dead battery, never had a problem starting, but something is wrong - something is causing a drain, and I'd like to fix it.
DIAGNOSIS:
I do have the Mopar service manual and spent the last couple of days performing the procedure to find a parasitic draw according to their specs. (lock the vehicle, keep the key far away, wait ~30 mins. for all systems to shut down, then start pulling fuses until the draw drops). The service manual gives 20-30 minutes as the time needed for everything to shut down, but I found that I needed to wait exactly one hour for the Dual USB Port on the dash to stop drawing current. This checks out with other info I've found (think it's in the owner's manual - if not it's been referenced on this forum a few times) stating that the USB ports will continue to charge devices for up to 60 minutes after ignition off. I didn't have anything charging, but it seems that the USB unit is still drawing a small amount of current until that 60 minutes is up.
ANOTHER POSSIBLE CAUSE:
Service manual states between 5mA and 35mA is acceptable for ignition off. So, after 20-30 minutes amp draw is about 110-120mA. Pulling fuse F102 (Dual USB Port) brings amp draw down to about 70mA which is still around twice what it should be. I originally thought this was the issue, but not according to this test. After 1 hour pulling F102 makes no difference to current draw. I'm seeing the same thing consistently: ~110mA for the first hour, then 17mA after that with a periodic spike every 2-4 seconds up to 30-40mA. I'm guessing that's the RF receiver checking for the key fob? Regardless, it's still within spec for ignition off draw.
TLDR:
- Parasitic draw overnight (every night) down to 12.0-12.2 volts. This started ~6 months ago. Prior to that 12.5-12.7 volts in the morning.
- Batteries are never completely flat / never any issues starting
- Using two equally sized Odyssey AGM group 25 batteries and I have swapped them to make sure it's not the battery.
- Performed parasitic drain test according to service manual:
- Vehicle off
- Doors locked
- Key fob far away
- Ammeter in line between battery (-) and chassis ground cable
- Wait 30-60 minutes
- I'm seeing current draw of 110-130mA for first hour ignition off, then 17mA with spike up to 35-40mA every few seconds after that. Seems within spec.
- Pulled all fuses/relays individually and found no changes in amp draw after the first hour
- Left ammeter running for many hours today with GoPro recording the readings. Pored through those videos and found no spikes in current beyond ~40mA after the first hour.
I COULD USE YOUR HELP:
- HAS THIS HAPPENED TO YOU?: Has anybody else found these hood switches to cause a parasitic draw?
- EASY TEST: Can somebody please run a continuity test on their hood ajar switches? I have no continuity on EITHER switch in both open AND closed positions which I find very odd.
- MORE INVOLVED TEST: Is anyone willing to perform the test as I’ve described above to confirm that the #2 hood ajar switch causes a jump in current after the vehicle reaches its nominal ignition off draw? If this is normal behavior then I may have to drop this theory.
I must be missing something regarding the design of these switches. I always test the leads before testing for continuity. I’m using a new Fluke multimeter with new leads, both in excellent condition, and am an advanced hobbyist when it comes to electrical testing/circuit design/etc. It seems unlikely that both switches have no continuity since there’s no issues with ESS and no erratic hood ajar indications on EVIC.
Read below if it’s helpful to learn more about anything I’ve mentioned above.
DEEPER DIVE:
WORKING THEORY:
A variable which I'm looking into is the hood ajar switches. There are two near the driver side headlight. As I understand it, the inner switch (switch 1) simply tells the BCM and then the driver, via the EVIC, that the hood is open, and the outer switch (switch 2 - closer to the fender) is used to determine the hood position for ESS and Remote Start. ESS/Remote Start won't work if switch 2 is telling the PCM that the hood is open.
I realized this evening after two days of testing I never taped down those switches and since the hood has been open all this time, they've both been in the "open" position. After 1+ hour after ignition off and the Fluke reading ~17-40mA I decided to work each of these switches manually. The inner switch had no effect. The outer switch, however, woke something up. Depressing it causes a sudden draw of 4 amps which dies down to around 110mA after less than a minute. Interestingly, if I keep the switch depressed, wait for 110mA, and then release the switch, the current draw ALSO jumps up to 4 amps and follows the same pattern dropping down to 110mA.
I pulled both of those switches to test for continuity and to see if one of them has an intermittent connection. In theory this COULD explain the parasitic draw. Switching from either state to the other wakes up one of the logic modules, so an intermittent switch could be causing this several times throughout the night. A 4 amp draw multiple times overnight could definitely drain the main battery down to ≤12.2 volts.
They seem like straightforward switches. Two pins and a plunger switch connecting them. Thing is though - I couldn't get continuity across those pins in the open OR closed positions on BOTH switches. They are pretty dusty and dirty because of where they’re located, but I’ve never had an ESS issue since replacing the aux battery, and I don’t get intermittent “hood open” messages or anything like that.
DUAL BATTERY SETUP:
I have a rudimentary aftermarket dual battery setup. I used the Genesis DIY kit WITHOUT their electronics, though I am using the two group 25 Odyssey batteries that they sell. I already had a Redarc Smart Battery Isolator laying around and am using that to fully disconnect the aux battery at shutdown. This was a precautionary measure in case the main battery ever had a parasitic draw and it has turned out to be quite useful since the draw started. This worked just fine for many months. Main battery voltage was showing 12.5-12.7 on EVIC right before start up and, crucially, BEFORE I manually engage the Redarc solenoid and add the aux battery to the system. (I always check both batteries before connecting them and before starting the engine.)
THE PROBLEM:
For the past 6 months or so, however, the main battery always drains to 12.1-12.2 volts overnight. It very rarely goes to 12.0 volts and it absolutely never goes below that which suggests to me that something intelligent is causing the drain - something that has a built in low voltage cutoff. I've never had a dead battery, never had a problem starting, but something is wrong - something is causing a drain, and I'd like to fix it.
DIAGNOSIS:
I do have the Mopar service manual and spent the last couple of days performing the procedure to find a parasitic draw according to their specs. (lock the vehicle, keep the key far away, wait ~30 mins. for all systems to shut down, then start pulling fuses until the draw drops). The service manual gives 20-30 minutes as the time needed for everything to shut down, but I found that I needed to wait exactly one hour for the Dual USB Port on the dash to stop drawing current. This checks out with other info I've found (think it's in the owner's manual - if not it's been referenced on this forum a few times) stating that the USB ports will continue to charge devices for up to 60 minutes after ignition off. I didn't have anything charging, but it seems that the USB unit is still drawing a small amount of current until that 60 minutes is up.
ANOTHER POSSIBLE CAUSE:
Service manual states between 5mA and 35mA is acceptable for ignition off. So, after 20-30 minutes amp draw is about 110-120mA. Pulling fuse F102 (Dual USB Port) brings amp draw down to about 70mA which is still around twice what it should be. I originally thought this was the issue, but not according to this test. After 1 hour pulling F102 makes no difference to current draw. I'm seeing the same thing consistently: ~110mA for the first hour, then 17mA after that with a periodic spike every 2-4 seconds up to 30-40mA. I'm guessing that's the RF receiver checking for the key fob? Regardless, it's still within spec for ignition off draw.
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