Hybrid Battery Fan mistake to headache

Hey Yall, so to begin, I wanted to do some preventative maintenance on my gen 2 Prius which recently had hit 200k mi. So I decided to clean out the Hybrid Battery cooling fan. I didn’t have an air compressor to clean it out with and cleaned it out with water instead, I made sure to avoid the electrical connector as much as possible. I still dried with a fan with like 20-30 minutes.

When I put it back in, it took about 20-25 miles to throw a P3000, C1034, and P0A84. So I checked the electrical connector to the fan and it was there right and snug. I thought simply the fan was bad so I bought another used fan (-40$), and same thing happened. 20-25 miles yada yada. So I started testing out parts, jumping them individually and so on. To my surprise the water cleaned fan jumped perfectly fine. Fast forward a bit, I’ve checked out parts and I replaced the blower motor controller because I thought it was the problem. It wasn’t. (-20$)

So still in my diagnosing, i was checking the b14 battery fan relay. I was testing its resistance according to picture. 12v to relay pin 1 and 2, and probed 2k ohms and results were 0.01 ohm converting to 10 ohms of resistance. So I checked the 10A batt fan fuse. My test light showed it was okay, however when I multimetered it, dc volts, it displayed 6-7v. And the fuse socket displayed 3v.

so I’m asking, whats the next step I should take? I have not done electrical diags before. I literally just bought a multimeter. Also my hybrid battery is working just fine, I’m getting 35-40 mpg usually still but I haven’t driven long distances in one sitting due to this issue. I’ve also added media that I’ve been using.

 

you were right. I saw it before but I brushed it off. Literally and figuratively. I brushed the corrosion off because there wasn’t much. And thought that was fine. I spliced the wires brown wire, now no codes. Thanks for all the help!

 

Hey Yall! 30-50 miles later, the codes reappeared. Dread p0a84, P3000, C1034 … anyway I was baffled. Maybe it because one long test drive that finally the ecu to think yo we should turn battery fan and when tried it didn’t work. So, I swapped the water cleaned fan to the used fan and I did a battery reset. Still the codes returned immediately within 5 seconds of the ignition. What yall think?

 

Update! I spliced the black bm1 connector. I thought I had something because the copper wire had a blackish material on it. Nada, did nothing. I left the violet and light green wire alone since they looked clean.

So I took a few steps to look over everything again. I tested the relay and relay socket first because they are very easily accessible. B14 Relay worked fine when power is jumped through pins 1 and 2. However more important to note, ground, pin 3, grey wire when sent 12v did nothing. Also checked with a multimeter, dc 0v. I went back to the fuse box because between the relay and the fuse there is only one connector. Take high note of this. I measured 16v at the supposed fuse.

So I tore down the passenger kick panel to access the IN1 connector. Three wires, white, and two greys read dc 0v. So I kept going further up, visual inspection by removal of cowl and wipers and stuff. Visual inspection, nothing out of the ordinary. Went to the fuse box diagram again and it finally clicked to me. I was testing the wrong fuse the whole time. I was testing the hazard fuse instead of batt fan fuse. With a test light, it lit up one side, and not on the other. Blown fuse.

I tested the fuse much much earlier, but the car was off and I didn’t really know what my readings meant. Refer to “my fuse reads 3a…” I truly believe this was the issue. It made me rule out the fuse… I’ll check in after like a 40-60 mi drive in a bit.