Low battery error codes; water in wheel well.

So I was getting dashboard symbols popping up. The triangle, brakes, VSC, check engine. The ODB reader shows a C2318 code. Seems this happens if there is a ground or resistance issue in the transmission IGCT relay or fuse, OR like many other weird problem, a low voltage situation with the auxiliary/starter battery. So I charged the battery using the front fuse panel contacts and the voltage is 12V or above. So I took the battery out and discovered the battery sitting in 2 inches of water! It is a 5 year old optima yellow top so it may be bad, but was wondering if anyone had any experience with batteries in water, or a similar issue with water in the wheel well. I have the battery on a good charger to see if it can pass a load test. What a weird one. Any thoughts?

Well, a little more info. I cleaned up the water, the battery took a full charge quickly. I brought it to NAPA and they load tested it and it was fine. I cleaned the contacts as suggested in error report. If I turn off the car and restart the codes come right back. Only thing showing is the C2318 codes.

 

Again more info, I brought the Prius to Toyota. They are telling me after analysis that it needs a new hybrid battery. Surprised. There is NO code fo P0A80 or something on the high voltage side. The only code is on the 12V side for C2318. Any help out there? Seems like an expensive adventure if the hybrid battery isn't the problem.

 

Thanks, I trust the load tester, but no harm in doing this test as well. Voltage at the front after the car sits for 12 hours was 12.5V.

Any idea where the IGCT Relay is located? Interestingly I can start the car and clear all codes. IT will drive for ever running correctly (no fan noise, etc.) until I stop and try to restart. Then it throws the trouble lights and C2318 code.

 

The codes were pulled using an Autel ODB reader as a well as a high end SnapOn scanner. The dealer tech "says" he pulled a series of codes all pointing at a new HV battery and rattled off a list ( no print out). My trusted mechanic and I don't get those main codes which leads me to being suspicious. Was he not able to identify the problem and made one up to get the car off the lift? He conveniently did not enter any notes in the account record either so I want to verify his work. The Prius has 82,000 miles on it. They also did not charge me ( even though they said they would). A nice gesture but you also have to wonder, they can't be held responsible for anything if they don't charge me. I want to get the diag protocol for the C2318 code and see if I can get a copy of Techstream working before I load in a refurbed HV battery. My hunch is its a harness wiring issue.

 

There a few members who have mentioned receiving a C2318 code, but never close out their threads with a resolution. Please post your final resolutions, its really valuable to the forum.

 

Ed, I check this first thing thanks to Mikes video. Its completely sealed, even the paint isn't cracked. Beats me how that water got in there. Nothing in the real of the car is wet and no mildew at all. Puzzling. Battey hlods voltage well, snaps back to 12.2V

 

Drops to about 11.5 V measured by the display diagnostics. I need to get TechStream software up and running on my laptop. I should have the cable tomorrow. This will let me check the voltage at the transmission controller where it is sensored. Also if there is any evidence the HV battery needs replacing.

I learned something new I could not figure out. The C2318 code says to check the function of the IGCT Relay. Where is this relay located? This is marked as "P-CON" in the primary fuse box under the hood.

 

Really good idea. The fan is working ok. Absolutely no water corrosion or staining anywhere so this looks like a brand new problem. Wondering if someone drove through a DEEP puddle and won't fess up. Family diagnostics maybe required.