Need help diagnosing P0AFC

Would appreciate some help figuring this out. A couple weeks ago, my 2010 threw DTC P0AFC. There were a few other codes (C2175, C1202, C1256, C1259, C1310, U0155), but I'm thinking they're all just random codes triggered by whatever is causing the P0AFC. Not sure what the U0155 is, I've seen that a lot on and off over the years without noticing any actual issues.

Anyways, I checked my battery voltages using Dr. Prius and Techstream, and it's showing Block 04 at 0.00V, and Block 05 at nearly 25V. Trying to figure out if I just have two bad cells, or if something else is going on. If it's just two bad cells, why would one suddenly drop to 0V while the next jumps to 25V?

The car seems to drive okay, it's just the ICE is constantly running.

Here are some screenshots:


Any ideas or diagnostic suggestions?

 

Not sure why the tpms might be throwing a code, as I just had all 4 sensors replaced while getting new tires...

As for the U0155, if you look at the screenshot, it's the Smart Key ECU reporting the code.

Hmm okay. Since I'm going to have to dig in to the battery and look for a bad connection, is there anything else I can take care of at the same time? From what I've seen, I can clean the bus bars and the battery fan. Anything else?

 

Do you happen to have page numbers for P0AFC? And C2175 as well, but I think the more important thing right now is the P0AFC.

Also, I just looked again, and it's actually P0AFC-123.

Also figured out how to PDF the freeze frame data. I've attached it here, if anyone can help me interpret it.

 

Found it. Pages 3817 - 3823 of 7595. Will have to take a shot at this.

@ChapmanF Thank you for pointing me this way. I'm still lost, but not completely lost anymore

 

What is the Universal Trip the repair manual says to perform after clearing codes?

 

Any tips on removing relays from the fuse block? Trying to remove the IGCT relay to test, but haven't managed to take it out.

I popped off the plastic cover for the relay, but not the actual relay... Not sure that was supposed to happen

 

Nevermind. I removed the two relays under it, and was able to finally get the IGCT relay off. Damaged the plastic clips for the plastic cover, though, so that could be an issue in the future.

I do need help deciphering my measurements, though

Code:

https://imgur.com/a/TpVv89N

According to this (pg. 3821 of 7595), I should get under 1 ohm when I measure across 3 and 5 without 12V applied across 1 and 2. I get 0L (infinite resistance/no connection, unless I'm mistaken). With 12V across 1 and 2, it says I should get over 10kOhm, but I get a click and continuity/0 Ohms. Additionally, with no voltage applied, I measured about 170 Ohms across 1 and 2. What am I doing wrong?

There's a DIM/DRL relay near the IGCT relay, and they seem to have the same part # so I did the same test on that one, and got the same results...

Actually, my test results make sense to me, and indicate a good relay in my opinion. The test conditions don't make sense to me, and seem opposite from what it should be... If there is voltage between 1 and 2, then the switch should close between 3 and 5, meaning continuity/0 resistance -- which is what I got. With no voltage, the switch should be open, meaning infinite resistance -- again, what I measured. But why would the repair manual be saying the opposite??

 

Not yet. I haven't had a chance to open up the battery to take look at the wiring harness or smart battery unity, but I'm 70% certain my issue is going to be corroded pins on the smart battery unit, in which case I can hopefully just replace that one unit.

 

When the repair manual says to check voltage on the IGCT in step 1 (CHECK HARNESS AND CONNECTOR (IGCT VOLTAGE)), do I disconnect the connector and check voltage? Or do I poke around for bare wire to check voltage with everything connected? Kinda confused here

Page 3819 of 7595

 

Hmm I don't see the probes in the illustration, but yeah that makes sense. I'll have to figure out how to get my leads in that way.

A couple other things that are unclear to me from the repair manual:

• When it says to disconnect or connect the cable from the negative battery terminal, it's talking about the 12V battery, right?
• In step 4 (CHECK HARNESS AND CONNECTOR (IGCT RELAY - BATTERY SMART UNIT)), I'm checking the resistance between the c1 connector and the IGCT relay terminal, not the relay itself, correct? So like the terminal in the fuse block, not the blade on the relay? Just making sure. In that case, I'd need pretty long wires on my test leads... or just extend them with like alligator leads or something I guess?

 

I really can't figure out how to measure the voltage with the connector still connected. There's not much space there where the individual wires go into the connector. Definitely not enough space for my multimeter's test leads. I tried with paper clips, with alligator clips in between my test leads and the paper clips. I'm not sure that the paper clips are making actual contact with the wires, though, as I'm not getting much in terms of voltage readings