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Seemingly dead Prius turns on when touching negative battery terminal

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by clockworkjeremy, Dec 21, 2018.

  1. Skibob

    Skibob Senior Member

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    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? :mad:
     
  2. terramir

    terramir Member

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    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
     
  3. voltech444

    voltech444 Junior Member

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    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.
     
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  4. voltech444

    voltech444 Junior Member

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    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.
     
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  5. Landon51

    Landon51 Member

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  6. voltech444

    voltech444 Junior Member

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    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.
     
  7. Mendel Leisk

    Mendel Leisk Senior Member

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    Don't want to stir up the hornets nest (or do I... :sneaky:), but I'm not to sure about greasing battery terminals. From the factory they're not greased, fwiw.
     
  8. voltech444

    voltech444 Junior Member

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    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.
     
  9. audiodave

    audiodave Active Member

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

    Posted via the PriusChat mobile app.
     
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  10. Mendel Leisk

    Mendel Leisk Senior Member

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    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.
     
  11. voltech444

    voltech444 Junior Member

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    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.
     
  12. Natalie Opsahl

    Natalie Opsahl Junior Member

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    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?
     
  13. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    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.
     
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  14. fuzzy1

    fuzzy1 Senior Member

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    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
     
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