Battery Drain - 2008 Acura MDX with a 3.5L V6 SOHC 24V engine

Michael Owner/Technician Irving, Texas Posted   Latest  
Question
Electrical
2008 Acura MDX 3.7L (J37A1) 5-spd (BYFA)—2HNYD28508H520882
Battery Draw

I have a battery drain with the driver door MPCS Unit plugged in. I can hear a relay click in the module and I'll have a 2.7 to 2.9 amp draw when I plug it back in (ignition off). I check the basics.... the Handsfreelink Control Unit, Air Conditioning (A/C) Clutch Relay, and the Blue Tooth Module with no luck. I have a feeling the relay in the module is my draw, but for the life of me I can't figure out the wiring diagram as the wiring doesn't seem to match the vehicle. I'll try to work thru all the wiring tomorrow, but was wondering if anyone has seen this issue before and maybe have an explanation as to why the wiring doesn't seem to match the vehicle or what relay inside the module may be turning on (driver windows switch is unplugged). Module has been replaced with a used one ans the only connection left in the door is the module (everything else unplugged).

+1
Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
 

Do a quick double-check that every single door latch and door lock changes state, in the appropriate data list, when open/closed/locked/unlocked. Anyone acting silly keeps the system awake. Read that story a couple times on Honda brands.

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Timothy Diagnostician
Brampton, Ontario
Timothy Default
 

Not to forget tailgate button state changes aswell, especially in the rust belt.

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Eli Owner/Technician
Toronto, Ontario
Eli Default
   

This is a serious draw and something should be warm. Let the vehicle cool off overnight and in the morning use an infrared thermometer to poke around the cluster and under-dash looking for a temperature anomaly. Check the temp of tailgate wiper motor too.

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Michael Owner/Technician
Irving, Texas
Michael Default
 

The 2.9amp draw is only present when the relay turns on when the module is plugged in. The “A” connector unplugged, the drain is gone. I see two power circuits, 2 communication circuits, and a relay control circuit going back to the fuse box that powers the window relay. Everything else is unplugged. I tried to test the circuits, but the schematic didn’t seem to match the wiring. I’ll trace all…

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Randy Diagnostician
Glendora, California
Randy Default
 

Unplug the drivers door cylinder lock

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Michael Owner/Technician
Irving, Texas
Michael Default
 

That may be something I may have missed. Didn’t even think to look if it had one.

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Freddie Owner/Technician
Houma, Louisiana
Freddie Default
 

On some older Mercedes replacing a battery and not resetting the window up and down setting would cause a battery draw.

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