Parasitic Draw - Master Window Switch?
#1
09-07-2020, 10:25 AM
Parasitic Draw - Master Window Switch?
2008 Honda Accord EX-L, 4-door sedan, 4-cycl engine, auto trans.
Bought this car 2 months ago and was told something was draining the battery when the car sat for 2-3 days, requiring it to need jumped to start. So, went in with my eyes open. Battery is 1 1/2 years old, but had it tested at a local parts store and they assured me the battery, alternator and starter were all in great condition.
So, using a fully charged battery, I connect my multi-meter up to check for parasitic draw (red lead to negative battery cable unhooked and black lead to negative battery post). I see a .36 amp draw initially. I start pulling fuses in the engine compartment box and fuse #15 (10 amp) is the culprit. Reading on the meter drops to .02 amps. Those of you familiar with this B-Can fuse listed as "Back Up" know that it provides power to about 2 dozen different items (audio unit, driver's door courtesy light, passenger door courtesy light, gauge control module, HFL system, Navigation system, Immobilizer Keyless Control, Master Power Window drivers side door switch, Drivers MICU, Passengers MICU, and on and and on.......).
Working it from there, I discover that by unplugging the Master Power Window Switch, the reading drops to .03 amps. I have not went any further. I ordered a replacement switch and I have the same issue with it installed. All of the windows and locks worked fine using this switch and also worked with the old switch I just replaced. Have I not went far enough down stream I wonder?
When I initially hook up the meter, the door locks engage and I get a reading of .36 amps. 1 minute and 15 seconds later, this drops to a reading of .26 amps. I assume this is the car going into "sleep mode", but I have read that this should only take 30-40 seconds, so seems longer than usual if correct. When I unplug the wiring harness from the Master Power Windows Switch, it takes 7 minutes before the meter reading drops to .03 amps. Should it take this long? I would think it would be instantly.
So, if you have read all of this - thank you. I am trying to understand if the Master Power Window Switch seems logical to be the root cause of this battery drain, or if I stopped digging prematurely when it appeared to be. If anyone else has disconnected this switch previously, did it take 7 minutes to drop amperage? Since I replaced the switch, this is not something that would have to be reprogramed is it?
Bought this car 2 months ago and was told something was draining the battery when the car sat for 2-3 days, requiring it to need jumped to start. So, went in with my eyes open. Battery is 1 1/2 years old, but had it tested at a local parts store and they assured me the battery, alternator and starter were all in great condition.
So, using a fully charged battery, I connect my multi-meter up to check for parasitic draw (red lead to negative battery cable unhooked and black lead to negative battery post). I see a .36 amp draw initially. I start pulling fuses in the engine compartment box and fuse #15 (10 amp) is the culprit. Reading on the meter drops to .02 amps. Those of you familiar with this B-Can fuse listed as "Back Up" know that it provides power to about 2 dozen different items (audio unit, driver's door courtesy light, passenger door courtesy light, gauge control module, HFL system, Navigation system, Immobilizer Keyless Control, Master Power Window drivers side door switch, Drivers MICU, Passengers MICU, and on and and on.......).
Working it from there, I discover that by unplugging the Master Power Window Switch, the reading drops to .03 amps. I have not went any further. I ordered a replacement switch and I have the same issue with it installed. All of the windows and locks worked fine using this switch and also worked with the old switch I just replaced. Have I not went far enough down stream I wonder?
When I initially hook up the meter, the door locks engage and I get a reading of .36 amps. 1 minute and 15 seconds later, this drops to a reading of .26 amps. I assume this is the car going into "sleep mode", but I have read that this should only take 30-40 seconds, so seems longer than usual if correct. When I unplug the wiring harness from the Master Power Windows Switch, it takes 7 minutes before the meter reading drops to .03 amps. Should it take this long? I would think it would be instantly.
So, if you have read all of this - thank you. I am trying to understand if the Master Power Window Switch seems logical to be the root cause of this battery drain, or if I stopped digging prematurely when it appeared to be. If anyone else has disconnected this switch previously, did it take 7 minutes to drop amperage? Since I replaced the switch, this is not something that would have to be reprogramed is it?
#2
09-07-2020, 12:04 PM
I've read that 10-15 minutes to get to sleep mode is reasonable for modern vehicles.
Did you go through all of the fuses and did the other fuses not cause a reduction in amps? I think your accord has 2 interior fuse boxes on the driver and passenger side of the cabin.
That white wire on the #15 fuse feeds a lot of items. It sounds like something in the system is preventing the MICU from going to sleep mode. You may have to start unplugging the window motors, door lock actuators to see if one specific component is the root cause. This gets pretty tedious when the system contains communication from the power window switch to the MICU.
Did you go through all of the fuses and did the other fuses not cause a reduction in amps? I think your accord has 2 interior fuse boxes on the driver and passenger side of the cabin.
That white wire on the #15 fuse feeds a lot of items. It sounds like something in the system is preventing the MICU from going to sleep mode. You may have to start unplugging the window motors, door lock actuators to see if one specific component is the root cause. This gets pretty tedious when the system contains communication from the power window switch to the MICU.
#3
09-07-2020, 12:12 PM
I've read that 10-15 minutes to get to sleep mode is reasonable for modern vehicles.
Did you go through all of the fuses and did the other fuses not cause a reduction in amps? I think your accord has 2 interior fuse boxes on the driver and passenger side of the cabin.
That white wire on the #15 fuse feeds a lot of items. It sounds like something in the system is preventing the MICU from going to sleep mode. You may have to start unplugging the window motors, door lock actuators to see if one specific component is the root cause. This gets pretty tedious when the system contains communication from the power window switch to the MICU.
Did you go through all of the fuses and did the other fuses not cause a reduction in amps? I think your accord has 2 interior fuse boxes on the driver and passenger side of the cabin.
That white wire on the #15 fuse feeds a lot of items. It sounds like something in the system is preventing the MICU from going to sleep mode. You may have to start unplugging the window motors, door lock actuators to see if one specific component is the root cause. This gets pretty tedious when the system contains communication from the power window switch to the MICU.
Last edited by Accord2020; 09-07-2020 at 12:19 PM.
#4
09-07-2020, 05:07 PM
The driver's master switch also controls the lock actuator and windows on the other 3 doors. You may want to unplug the passenger door switch, then the rear doors to see if you can isolate the issue that way. This system is also tied to passenger multiplex control unit it the passenger interior fuse box. This system is complicated, because the door multiplex and both MICUs are all tied into each other.
Looking at the shop manual, the #15 fuse also feeds the obd2 connector. Is there anything plugged into it? It is unlikely, but worth a quick look.
Looking at the shop manual, the #15 fuse also feeds the obd2 connector. Is there anything plugged into it? It is unlikely, but worth a quick look.
#5
09-07-2020, 05:32 PM
The driver's master switch also controls the lock actuator and windows on the other 3 doors. You may want to unplug the passenger door switch, then the rear doors to see if you can isolate the issue that way. This system is also tied to passenger multiplex control unit it the passenger interior fuse box. This system is complicated, because the door multiplex and both MICUs are all tied into each other.
Looking at the shop manual, the #15 fuse also feeds the obd2 connector. Is there anything plugged into it? It is unlikely, but worth a quick look.
Looking at the shop manual, the #15 fuse also feeds the obd2 connector. Is there anything plugged into it? It is unlikely, but worth a quick look.
Yeah, this is a bad one to land on; so much on it to run down....... I can't imagine anything is plugged into the obd2 connector, but I will certainly check it.
Thanks,
#6
09-26-2020, 05:11 PM
Update: Took the car to the local Honda dealer and let them plug it in to zero in on the culprit. They replaced the under dash driver's side fuse box. 1 week later and it appears to be good to go. No issues since.
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