Need help with parasitic draw on my 2005 CRD

Serious question —

I am wondering how you guys check for parasitic draw on the dash end fuse panel without opening the door and setting the interior light on, this creating an instant parasitic draw ??

I am sure that there is a really simple solution that I am totally missing, so please feel free to insult me while you provide the answer.

ALSO, diving further into the problem, it seems like I have a .4 amp ignition off parasitic draw traveling through the ground cable.

And when I remove 2/3 of the 50amp JB Power fuses in the engine fuse box, it drops from .407a to .034a in steps as I remove each 50 amp fuse.

My problem is … I have NO idea what the JB power fuse supplies…again, I am already feeling particularly stupid today having blown the DVM 20 amp fuse once already while putting the battery on the trickle charger for more testing tomorrow, so insults are warranted and welcome.

It is also possible that I am not giving the ECM and modules enough time to got to sleep, which brings me RIGHT back to the first problem of opening the door to check the dash fuses for current drop.

ALL ideas welcome.

OK just learned that all 3 "JB power" 50a fuses are the supply circuits for the interior junction box fuses, so still need to know how to check the dash end fuses for draw with the door open!!! Anybody wanna call me stupid by giving the obvious answer that I must be missing??

ALSO gonna start looking at the wires in the door loom for a short

Before you get too involved in chasing it try pulling the radio fuse and see if that has any affect.
I'm not sure where the interior light switch is in the door, just looked at mine and it's not obvious, it may well be in the door latch, if so then resetting it with a screwdriver will switch it off.

KJowner said:

Before you get too involved in chasing it try pulling the radio fuse and see if that has any affect.

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Ok Ill try that first.

KJowner said:

I'm not sure where the interior light switch is in the door, just looked at mine and it's not obvious, it may well be in the door latch, if so then resetting it with a screwdriver will switch it off.

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Mrs. AI Interwebz seems to confirm the existence of a latch switch, so I will try the screwdriver "closing" and see what happens.

God how I often miss the days of simple analog switches as opposed to todays microswitches!!!!

I think you can find circuits that are consuming power by removing suspect always-on fuses one by one and reading the change in dark current, as you did with the junction box.
If you are concerned about the current value of the interior light, remove the interior light bulb.
If you disconnect the devices on the suspect power supply circuit one after another, you will reach the cause.
If there is a leak from a cable or terminal, I think it would be a good idea to read the current value of those wirings with a loop probe.

ikuo78 said:

If you are concerned about the current value of the interior light, remove the interior light bulb.

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Yes that is a good idea and is actually my backup plan … but I didn;t want to risk breaking the stupid plastic switch/lenses while trying to take the bulbs out so I will try to close the latch first with a screwdriver.

Diagnostic Update —

I charged the Duracell (USA made by East Penn!!!) lead acid battery overnight with the ground wire disconnected, then opened the door and closed the latch with a screwdriver. @KJowner your idea worked great to keep the interior lights off even after I “reconnected” the ground wire and negative terminal by attaching the DVM leads (with the DVM set to read up to 20A) but also keeping the door open in order to access the dash end fuse panel.

Immediately the DVM registered .378 amps and stayed there as I pulled each and every fuse in the interior junction box which zero change in the current flow registering on the DVM until after 10 minutes I saw it drop to .055 and then eventually .034 but with NO change as I pulled each and every fuse UNTIL I also pulled the BCM double fuse when it dropped to 0 and then rose up to .378a when I plugged it back in.

In my mind, this means that the BCM module, or one of the sub modules farther down the same circuit, is taking longer to go to sleep then it should be (supposed to be closer to 3 minutes). I triple checked this idea 3 times by removing the BCM fuse and then plugging it back in and each time the DMV current read 0amps then rose to .378 until it dropped to .034 after almost exactly 10 minutes. While this is inconvenient, it is NOT necessarily a major problem as the BCM itself IS eventually going to sleep and the final .034 amp draw is at the high end of the allowable draw spec, but STILL within specs.

After all of this diagnosis (took about an hour), I checked voltage at the battery and it was 12.69 and then I also put a carbon load tester on the battery. IMPORTANT NOTE: I always load test batteries with the ground terminal disconnected to prevent voltage or current spikes that might EASILY **** up one of the modules, or even the ECU, right after I have determined that they were all pretty much good !!!

Finally, I carbon load tested the battery at 400 amps that showed the battery still good at 10.5 volts. After load testing the battery recovered to 12.6 volts.

My final conclusion is that likely one of the sub modules within the BCM circuit is taking longer to go to sleep and thus eventually drawing down the battery after not driving for a couple weeks. It is also possible that the battery is on the verge of failing even though it still showed good.

I might cure this inconvenience by either removing the JB fuse that supplies the BCM circuit, or maybe pulling the BCM fuse at the dash fuse box, or maybe adding a ground disconnect switch at the battery, or maybe plugging into a solar or other trickle charger when I am not riding Maya for more then a week. Eventually I will buy a new battery when this one dies completely.

Good bit of detective work. I wouldn't completely disconnect the battery when you leave it because the gearbox ecu will have to relearn every time you go for a drive.

On my 06, if the door is opened it "wakes up" the BMS and it stays active for some 15mins or so, with higher current. And the door open signal is in the latch (I think) since the BMS can detect a partially open front door without the dome lights coming on.

An easier way to measure current draw is to disconnect the neg batt terminal, and put a current meter between the loose neg cable end and the batt. You will need to use a fairly low current range on the meter (unless your meter is auto ranging), so you will want a jumper to bypass the meter at first, until the BMS calms down and gets to its "idle" current. Do this with the door open so you can access the fuse panel. take the jumper off (if you're using it) and you will read the idle current. Now you can start pulling fuses until you find the one(s) that cause the current to drop to a normal level (20-3-ma, IIRC).

Steve777 said:

On my 06, if the door is opened it "wakes up" the BMS and it stays active for some 15mins or so, with higher current. And the door open signal is in the latch (I think) since the BMS can detect a partially open front door without the dome lights coming on.

An easier way to measure current draw is to disconnect the neg batt terminal, and put a current meter between the loose neg cable end and the batt.

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Yup that is exactly what I did, BUT opening the drivers door and closing the latch with a screwdriver with the battery ground cable removed but BEFORE attaching the DVM cables as you described, makes it so the the BCM doesnt even see the open door and doesn't wake up in the first place. win/win

seafish said:

Serious question —

I am wondering how you guys check for parasitic draw on the dash end fuse panel without opening the door and setting the interior light on, this creating an instant parasitic draw ??

I am sure that there is a really simple solution that I am totally missing, so please feel free to insult me while you provide the answer.

ALSO, diving further into the problem, it seems like I have a .4 amp ignition off parasitic draw traveling through the ground cable.

And when I remove 2/3 of the 50amp JB Power fuses in the engine fuse box, it drops from .407a to .034a in steps as I remove each 50 amp fuse.

My problem is … I have NO idea what the JB power fuse supplies…again, I am already feeling particularly stupid today having blown the DVM 20 amp fuse once already while putting the battery on the trickle charger for more testing tomorrow, so insults are warranted and welcome.

It is also possible that I am not giving the ECM and modules enough time to got to sleep, which brings me RIGHT back to the first problem of opening the door to check the dash fuses for current drop.

ALL ideas welcome.

Click to expand...

2 auto electricians were unable to find the cause, I even made a rig to detect the drain from outside the car. Eventually put a switch wired to the body control fuse in the main fuse box and fitted that hidden up inside the grille. Saved me buying a new red-top battery every year and certainly stops the false alarms we had been getting.

medler1 said:

2 auto electricians were unable to find the cause, I even made a rig to detect the drain from outside the car. Eventually put a switch wired to the body control fuse in the main fuse box and fitted that hidden up inside the grille. Saved me buying a new red-top battery every year and certainly stops the false alarms we had been getting.

Click to expand...

How high was the IOD parasitic draw ??

Do you still need the junction block legend to know all the fuses involved on it?

blackhawk said:

Do you still need the junction block legend to know all the fuses involved on it?

Click to expand...

Nope thanks all better.