Seemingly dead Prius turns on when touching negative battery terminal

Yes they sell new negative cables and positive clamps at the dealer. My dealer had to order both when I needed to put mine back to the original size. The thing that made me mad was you have to order the nut that goes on top of the positive terminal separately. 20 some bucks and you can’t throw in the bolt?

 

LOL yeah the stealerships charge a pretty penny lol just using the steel ring from a clamp enlarges the post so much it will take years to need new clamps.
terramir

 

I am having a very similar issue on a customer's vehicle. as soon as you connect the negative on the 12 volt, the car goes into the ON position, I can hear one contactor close, I believe it's the pre-charge relay. then you have to put the key fob into the slot, because the smart key doesn't work on this vehicle, I've also turn off the smart key feature, put your foot on the brake and push power button, the car starts and goes into ready mode. besides having a problem with the ABS system, the car does run and drive fine, so the engine, transmission, Hybrid battery, 12 volt battery are all good (all the data looked normal on TS). I swapped in a different 12 volt battery I use in my shop, and I have to disconnect it to turn the vehicle off. when you try to turn the vehicle off, the vehicle attempts to power down and you can hear the contactors open, the vehicle goes out of ready mode but stays in ON mode, and throws up a red triangle and a bunch of other lights. The ready button flashes red. The main code I get is P3110 HYBRID CONTROL SYSTEM: P3110/223, P3110/527 HV MAIN RELAY MALFUNCTION (2005 PRIUS) : DIAGNOSTICS INSPECT INTEGRATION RELAY(IGCT RELAY AND IG2 RELAY) DTC No. INF Code DTC Detection Condition Trouble Area P3110 223 IGCT relay is always closed Wire harness or connector Integration relay (IGCT relay) P3110 527 IG2 logical inconsistency Wire harness or connector Integration relay (IG2 relay). Theres also codes for ABS/VSC/TRAC as i would expect. it's worth noting this is a flood car, and the owner attempted to fix by replacing the HV main relay I'm talking about. so that's what I'm going to go after, pull that out and start following some of the testing on that circuit. here's a little more info for the diagnostic procedure: (a) Remove the integration relay from the engine room R/B. (b) Inspect the IGCT relay. (1) Check the resistance between the terminals of the integration relay. Standard: Tester Connection Specified Condition A4 − C1 10 kΩ or higher A4 − C1 (Apply battery voltage to terminals A2 and A3) Below 1 Ω (c) Inspect the IG2 relay. (1) Check the resistance between the terminals of the integration relay. Standard: Tester Connection Specified Condition B4 − C1 10 kΩ or higher B4 − C1 (Apply battery voltage to terminals B2 and B3) Below 1 Ω NG REPLACE INTEGRATION RELAY (IGCT RELAY OR IG2 RELAY) Most likely a short to ground, its just odd because normally if theres no key in the vehicle it cannot go into ACC or ON position, but the short must be bypassing the security and immobilizer system. I'll update on here what I find.

 

just wanted to give a quick update. I found the problem there is a short to power going to the igct relay, so as soon as you connect the negative on the battery it closes that relay and keeps it closed even when you try to turn the vehicle off, and that's when it codes out. the orange wire J2 connects to A2 (relay coil) exits out A3 as a white+black wire J3 that goes to ground. the orange wire J2 connect to the hybrid control ECU and also the ignition switch. these people did a engine and trans swap on this and they made several mistakes that I've had to find and fix, somewhere probably buried under the dash orange wire is short to power. or the hybrid control ECU is bad, which is possible considering this was a flood vehicle. unplugging the power button and key fob slot makes no difference, if you have the driver door open it will keep beeping thinking that there's a key in it when there is not. With all that disconnected it's still Powers up when you connect the negative. I bench tested the HV main relay and it works properly. I might try a simple fix to see if it is possible to manually control the igct relay by disconnecting the orange wire and putting a switch to give it 12 volts. I think the timing would be very critical, you would have to turn it on right as you're hitting the power button, and you would have to turn it off at the same time you're pushing the power button, or else it will code out with the same error it has now. that's not a permanent fix, just trying to prove that this is indeed the problem although at this point I have enough proof to be sure. really I'm just curious to see if it's possible to manually control it without the vehicle getting upset.

 

M

Posted via the PriusChat mobile app.

 

Just an update, manually controlling the relay did not work. Have to remove dash and find short, if there is one, if there's not then the hybrid control ecu is bad.

 

Don't want to stir up the hornets nest (or do I... ), but I'm not to sure about greasing battery terminals. From the factory they're not greased, fwiw.

 

I don't grease the terminals, however its probably worth doing, i've seen the 12v terminals get really corroded on other vehicles, but with the 12v being inside the car its pretty well protected so not really mandatory. How did I fix this car? The customer didn't want to pay for more diagnostic work so I offered a hillbilly workaround, put a battery disconnect switch on the negative of the 12v. The car runs and drives fine (except for an ABS light, but still works) it only freaked out when you tried to turn it off and one of the contactors won't close. I would've liked to get an answer, but at least I got it narrowed down, if you're having these issues definitely follow the diagnostic steps I provided above.

 

There's not much draw on the battery to corrode it besides being inside the car.

Posted via the PriusChat mobile app.

 

Posts and clamps don't come greased from the factory, and at least for our garage queen, I've never noticed any crud building up. Latest battery looks like new, 4.5 years in.

 

I recently worked on a 2002 Prius with 225k miles, original 12v, hybrid battery, basically everyhing was original. But 17 years on a 12v? Wow that's an amazing accomplishment! It had a burnt stator on MG2, they were willing to pay me $1,584 to swap the engine and trans but I advised them to just sell it and get a gen 2, put their money in a better car. They were really connected to the car and pleaded with me to do it, 2 years ago I would've but now I'll refuse to do work if I think it doesn't make sense for the customer, and me.

 

My car does this. It will have no power nothing and as soon as I pull the seats down to crawl through the car to mess with the battery then I hear a 'BEEP BEEP' And surprise it's back on again! What would happen if while driving this shorting out happened?

 

Once you get it going the DC/DC converter will supply all the power the car needs. Clean/tighten/replace those connections at the battery and crawl no further.

 

This isn't a "short circuit", it is the opposite, an "open circuit".

The former is commonly associated with sparks and fire and smoke and other damage. The later is commonly associated with cold silent nothingness.

But as Leadfoot points out, if the open circuit is happening out at the 12V battery in the trunk, then nothing should happen while the car is already "READY". The inverter between the traction battery and the 12V system should be supplying all the juice needed

 

Hi @voltech444 my Gen 2 (2005) is also having similar issue, it jump directly IG-ON as soon as I connect the 12V battery and doesn't react anything to the POWER Button (not reacting even to long press and doesn't show any lights as well) but it does detect key (it thrown B2799 - immobilizer issue because I plugged the 12V and got the key on my pocket) it also shows the P0A0D and it stays stuck in IG-ON (only allow to switch between N and P) and it shows all screens on normally

The initial issue was not shutting down (also no reaction to Power button) and I had to shut it down by unplugging 12V battery and removing HEV Fuse, then I even left it overnight without 12V battery and disconnecting HV Fuse and leaving light switches on to try to "empty" any residual electricity, but no success as now it is a bit zombified.
I don't have this P3110 but also hadn't had chance to see the mechanics DTC readings (he has definitely better equipment than my bluetooth OBD2 + Car scanner)
Could this be cause by a stuck/glued ICGT relay?
Could the car fall into some special mode from having removed both 12V and HEV fuse and requires some specific procedure to re-activate it?

Thanks in advance,
Paulo

 

Not sure why you removed the safety interlock but P0A0D means the safety interlock switch is not locked in (step 3 below).

 

I removed the safety interlock out of desperation (for trying to reset everything) because it is jumping IG-ON as soon as I connect the 12V and no reaction from Power button. It probably raise when I connected just the 12V just to close windows before leaving it overnight without 12V and without HV battery as well.
So just like the B2799 it is a misleading error, maybe there were some more errors on that first issue that I cleared without paying much attention :|
Right now the main issue is the jumping directly to IG-ON (and not allowing to switch to READY) and not showing any errors as well, any ideias why it is stuck in IG-ON mode and no reaction to power button?

 

I have some idea about the IG ON: the power source ECU does seem to have a nonvolatile memory for its last power state; if it was IG ON before 12V power dropped for some reason, that's the state it goes back to when power returns.

As for why it is disregarding button presses, I am not sure, but there might be something more to that B2799 code.

 

I did kill him in a pretty nasty way (by 12V and HEV removal) because I didn't find the reason for the power button not working, all suggestions were pointing to problems on dashboard or dim lights and weak battery,
that immobilizer error only pops up when the key is not on the ignition (additionally do not know which key was there when it happened so I can have a different key on the ignition from it's last alive state.
Could this actually be the power button indeed dead? I suppose the mechanic checked tested it, but it is easy for them to discard it like: such things don't fail or would be not turning on if is the button.

 

Try putting the FOB into the dash slot prior to pressing the power button.

I have had the Power Source ecu do the same thing to me when disconnecting 12v when car is not ready. Put battery cable back on and the car immediately powers back up to the same condition it was in prior to the battery being disconnected. I was able to get it back in sequence by inserting the fob into the dash first.