Let's face it, chasing a parasitic draw can be challenging task. With later model vehicles having an increasing amount of fuse protected circuits. Not having the option of pulling fuses to eliminate circuits due to the possibility of waking up modules makes it even tougher.

For this diagnosis I started by load testing the battery which failed. This was a new battery the customer had installed last week. For testing purposes, I installed a battery from stock so we can accurately diagnose the vehicle. Next I connected a switched parasitic drain tester. This tool allows you to connect your multimeter in a true amp mode to measure the actual current flow in one position or direct connect battery to cable in the second position. This diagnostic can also be accomplished using an inductive low amp probe, but I find using the multimeter much more accurate and reliable. Once connected, I leave the switched parasitic drain tester ON (Connecting the battery directly to the cable) until the interior lights power down. It should now be safe to open the switch on the tester to force current through the multimeter. (Most meters have an internal fuse to protect them from higher current). 

With the switch in this position I can now read actual amperage draw on the battery. Specifications for this vary but most are about 50ma with some being lower, if you can find a spec definitely use it. Honda gives an acceptable parasitic drain of 50ma or less. Our vehicle had a fluctuating current draw between 340ma to 640ma, considerable higher than spec. This vehicle has a BAIID Device (Breathalyzer) so I started by contacting the company to find out what are their amperage requirements and get disconnection approval. I am told that if the vehicle owners do not initiate a power save on the device, it will pulse a draw of roughly 200ma as it runs a heater in the device. They recommend that vehicles using this device are driven daily. With their approval I continued with disconnecting the BAIID Device power supply. I had a current draw of 154ma, still above spec. With 28 fuses and 5 relays under the hood and another 30 fuses and multiple relays under the dash I decided to try a different approach. I was going to use heat to see if I could locate the fuse or relay controlling the circuit/s that are active. I have used this approach on larger current draws with success but never one this small.

I started by leaving the car alone for about 2 hours and letting the current draw do its thing, flow and hopefully generate some heat. Now I fired up my FLIR E6XT and scanned the under-hood fuse box looking for a clue, unfortunately nothing showed. I was expecting to see some trace of heat since all the power flows through this fuse box. Next, I moved my attention to under the dash, not removing anything just simply aiming and taking an image of the area of the fuse box. I saw something that did not removed the fuse box cover and as you can see the upper left row of fuses were showing hotter (White in color) but something above them was still standing out as seen in image below. Removal of the kick panel showed the truth in what was going on, a relay was staying engaged and running hotter than the surrounding materials. These images are from the software that comes with the FLIR E6 XT. The FLIR software allows you to make a complete analysis of the image including temperature reading, color manipulation and see the standard image, which the FLIR takes automatically to assist you to identify what you are looking at in your thermal image.

After a quick look at an interior fuse box component ID I was able to identify this was the power window relay. Removing the relay had dropped the current draw to 32ma, an acceptable amount. I followed up this by reading the window schematic to see that the relay is supplied battery voltage all the time and grounded by the Master Window switch. Upon removal of the switch witch this is what we found.

Someone had run a jumper wire on the back of the window switch connector between the relay control wire and ground. They had done this to make the passenger and rear windows operate not knowing what chaos they created. We replaced the window master switch and programmed the AUTO function. This resumed the normal window operation and left the current draw at an acceptable 32ma. 

Even though the current draw from the BAIID device is higher than Honda specification, the battery stays charged for multiple days now.

In summary, the time saved by thinking outside of the normal diagnostic routine and using tools and technology to my advantage saved me hours of hunting for this circuit. Thermal imaging is relatively new to automotive diagnostics and not without a learning curve for sure, but with a little time checking know good cars, finding the bad one will really jump out at you!