Locating Battery Blower relay

If you're looking for controller stuff and relay stuff for the HV battery, you're about as far away from it as you can possibly be.

The controller for the HV battery fan is located in the bottom air duct which is located between the bottom passenger side of the HV battery and the car chassis side vent located directly in front of the 12v battery. The controller is on the back of the duct tucked out of the way. The relay is located above the upper duct.

 

Battyery ecu is inside the battery, on the driver side electronics section

 

View attachment 211830 Hopefully this will help.

 

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The wiring diagram shows that the motor is speed-controlled via the low side. The motor's high side always has +12 volts (well, whenever the relay is energized), and its "GND" side is really wired to the motor controller, and won't be pulled down to actual body-ground voltage unless the highest speed is selected. At intermediate speeds it will be pulled down by intermediate amounts, and if the controller isn't being commanded to run at all, it will be up near battery voltage (so, zero volts across the motor).

People do seem to commonly assume that when the VSC/brake/ABS lights are on, the car must be talking about the brakes, and then if the brakes seem ok, it must not be talking about much, and so continue using it.

Something that maybe hasn't been publicized as much as it should be is that the brake ECU gets notified of problems elsewhere in the car. If there is a problem detected with the traction battery or hybrid powertrain, the brake ECU is notified so it will know it can't count on regen and will have to handle braking on its own. Those notifications will light the brake warnings on the dash, but that doesn't mean the car is just talking about some brake issue that can be dismissed by saying the brakes seem ok.

In this case, because you had the red triangle also, you know there was a problem elsewhere in the car, and the brake warning lights were likely just secondary to that.

The P0A84 definitely refers to the battery blower, saying its measured voltage (from the "GND" side of the motor, which as discussed above isn't literally at ground all the time) was lower than it should be. P3000 is just the HV ECU saying it's aware of a code from the battery ECU, which would be your P0A84. B1421 only means there wasn't strong sunlight on the dash when you pulled the codes.

C2310 and C2318 both refer to low supply voltage observed at the Transmission Control ECU (grandiose name for the circuit that moves the transmission in and out of Park). It gets supply voltage at a couple different terminals, one all the time (to retain its memory and such) and one only when the car is IG ON. C2310 means it saw something less than 10 volts at its always-supplied terminal, and C2318 that it saw something less than 9.3 at its IG-switched terminal. These codes don't always mean a problem with the 12 volt battery, as these voltages are measured at the transmission control ECU so they can also be affected by wiring or connector issues on the way there. But it wouldn't be unreasonable to pause here and check your 12 volt battery health and give it a good full charge if need be.

Any of these codes that show with 'snowflake' icons next to them in Techstream will have "freeze frame" data collected at the moment the code was set. You can click those icons in Techstream and get more details like exactly what voltage was being seen by the Transmission Control ECU at the moment it set each of those codes, and what it was trying to do at the time. That information might be worth posting here.

 

I don't think I know offhand any better ways to test it than what's in the repair manual.

 

if I remember correctly, the HV battery fan controller is identical to the one used for the cabin fan. Not 100% sure on this, tho.

 

Most apps like Hybrid Assistant have the ability to run the HV Battery fan through each of it's speeds, step by step.
I know for fact that my HA app can do all 6 speeds individually.

 

It would become crazy hot if it were actually used that way, as at intermediate voltages it would be dissipating large amounts of power.

Instead, the ECU sends it a train of pulses. It is either off, dissipating no power, or fully on, dissipating the minimum power it can in saturation. The ECU varies the motor speed by changing the width of the pulses, which changes the average voltage seen by the motor, but without ever really using the transistor as a variable resistance.

 

It is one of the active tests in Techstream too, seeing as you mentioned you have it.

 

It's really no use thinking of it that way, because it's not a resistance device.

Checking it in action as shown on HB-161 and HB-162 is the ticket. (However, I think there may be a typo in the definition of "A" in step 18. The basic idea here is that with speed 1 selected, the motor should be seeing 2 to 4 volts. The high side of the motor is always at battery voltage, 12 to 14ish, and that would put the motor's low side 8 to 12 volts above ground. Looking at the diagram, that should be the same voltage you see from the controller's VM to body ground, assuming your meter is slow-responding enough to show you average voltage and not the pulses. The relationship where that voltage is A−2 to A−4 would hold if A were your measurement from the motor's high side to ground. At least, that's the way I'm reading it.)