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2006 Prius, "ready" light not coming on and no start

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by autotech1100, Apr 16, 2011.

  1. autotech1100

    autotech1100 New Member

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    Hi everyone, I have a 2006 Prius that is giving me fits. The car is equipped with the smart key but it seems to be working normally. I insert the key, press the brake, and then press the power button like I am supposed to but the "ready" light doesn't come on and the car won't start. I checked the brake light switch and it is working correctly. 12v battery is charged and shows 12.35 volts. I have been tinkering with the car for the past three days and have only gotten the light to come on and the car to start twice out of the numerous tries. The last time it started the dreaded "triangle" and check engine light were on so I plugged my scanner in and got code P0A1F, I had a spare battery ECU so I replaced it, while I was at it I removed the battery and cleaned the terminals, there was only a very small amount of light corrosion on a couple of cells. All cells tested good and had uniform voltage. I haven't gotten the car to start since putting everything back together. I have a small amount of experience with these cars but I've got alot to learn. If anyone could offer any advice I would greatly appreciate it!
     
    #1 autotech1100, Apr 16, 2011
  2. vertex

    vertex Active Member

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    Model:
    Prime Plus
    I never saw this, but the manual says:

    P0A1F-123 Battery Energy
    Control Module
    Abnormal
    signal input
    from battery
    ECU (ROM/
    RAM
    malfunction)
    - HV battery
    system
    - Battery ECU
    Comes on Comes on DTC stored ​
    ​
    ​
    ​
    HV-177​

    P0A1F-129 Battery Energy
    Control Module
    HV battery
    voltage circuit
    malfunction
    - HV battery
    voltage circuit
    - Service plug
    grip
    - High voltage
    fuse
    - Battery plug
    - Battery ECU
    Comes on Comes on DTC stored ​
    ​
    ​
    ​
    HV-179​

    P0A1F-593 Battery Energy
    Control Module
    IG2 signal
    circuit of battery
    ECU
    malfunction
    - Wire harness
    or connector
    - Battery ECU​
    Comes on Comes on DTC stored     HV-183

    So, it you changed the ECU and still have the problem, it could be a harness issue.
     
    #2 vertex, Apr 16, 2011
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  3. autotech1100

    autotech1100 New Member

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    Thanks for the quick reply vertex. I think the car has 2 problems but one is hopefully fixed. Stupid me evidently didn't get the service plug in the battery pack fully seated. I got it to start awhile ago and the check engine light is now off , my scanner shows no pending codes or freeze frame data. The hybrid system seems to be working correctly and the hybrid battery seems to be charging just fine per the monitor, although the "triangle" and yellow "!" are still on. With the smart key I hit "lock" and then "unlock" twice and after doing that I was able to get a ready light and the car started. I let it run for awhile and drove it around the parking lot. Now after powering down it won't start again, even if I do the lock and unlock cycle. Any advice is appreciated!
     
    #3 autotech1100, Apr 16, 2011
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. I suggest that you disconnect the 12V battery for several minutes, then reconnect. This will clear any DTC logged by the hybrid vehicle and traction battery ECUs. Maybe the car will start but if problems remain, the DTC will come back.

    2. If by yellow "!" light, you mean the amber ((!)) warning light, that is a brake system light produced by the skid control ECU. Apparently your car has a problem in that area. The skid control ECU DTC will not clear by disconnecting the 12V battery, but I have previously posted on how to clear DTC by using a jumper wire on the OBD-II connector.

    3. If you manage to make the car READY again, check the traction battery state-of-charge gauge in the MFD. If it is getting low, then you should force-charge the battery by putting the gear selector in D, holding the car stationary by pressing the brake pedal with your left foot, then flooring the accelerator pedal with your right foot. This will force the gasoline engine to spin MG1 in the transaxle, which will provide power to the inverter to charge the traction battery.
     
    #4 Patrick Wong, Apr 16, 2011
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  5. autotech1100

    autotech1100 New Member

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    Thanks for your advice. I did have the 12v battery disconnected but not since I discovered my mistake in not having the service plug fully seated. I'm going to leave the battery disconnected overnight and see what happens. I will clear the skid control DTC by your method. I actually just did what you suggested about the battery. It showed that the traction battery had just over a half charge. I got it to fully charge using the method you described, afterwards I drove it around the parking lot a few times and it ran great other than the warning triangle and amber warning lights staying on.
     
    #5 autotech1100, Apr 16, 2011
  6. autotech1100

    autotech1100 New Member

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    Well, the problems continue. I reconnected the 12v battery this morning and the car immediately switched to ready and fired right up. After about 5 seconds the dreaded triangle light came back on. Hybrid system seemed to be working fine and charging correctly. I turned the car off and tried to restart it and got nothing, no ready light and no start. The check engine light never came back on and my cheapo actron scanner showed no codes. I disconnected the battery again and this time after reconnecting it the car still won't go into ready mode, but I did notice the triangle didn't come on this time. I really do appreciate all of the help so far from everyone here!
     
    #6 autotech1100, Apr 17, 2011
  7. autotech1100

    autotech1100 New Member

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    Update: After trying numerous times I finally got the car to boot. After about 15 seconds of idling in park the triangle light came on and my scanner read code P0AA6, Hybrid battery negative contactor circuit stuck closed. After seeing this I decided to go for a drive, I drove the car about 3 miles down the road and it did great but the triangle stays lit. Aaaaaarrrrrrrggggghhhhhhh!!! Now I'm almost scared to power the car down because I know what will happen!
     
    #7 autotech1100, Apr 17, 2011
  8. Patrick Wong

    Patrick Wong DIY Enthusiast

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    DTC P0AA6 means that there exists a high voltage ground fault. The three digit INFO code will help to narrow down the location of the fault. The car will refuse to restart, after this code is logged.

    Besides the master warning red triangle light, what other warning lights or MFD warning icons/messages showed up?

    If your OBD-II scanner does not pick up the three-digit INFO code associated with the DTC then you'll have to have a Toyota dealership retrieve it, or else invest in Techstream Lite.
    https://techinfo.toyota.com/techInf...hinfo/html/prelogin/docs/tsliteflyertinfo.pdf
     
    #8 Patrick Wong, Apr 17, 2011
  9. seilerts

    seilerts Battery Curmudgeon

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    Please tell us, is this a customer's daily driver, a trade-in/auction/wholesaler purchase, or a salvage rebuild? There is a particular combination of subcodes for P0AA6 (526 + 613) that indicates a transaxle failure. Getting the secondary codes read would be very helpful.

    Keep that 12V on a charger, it may not be getting any juice from the DC-DC while the code is set.

    Please compare the picture below to your HV battery connection, just in case something is missing.

    EDIT: As far as the relays go, start by having the 12V disconnected for 5 minutes. Then connect the 12V, put foot on brake, and press the power button. In between pushing the button and seeing Ready, you should hear three clicks, corresponding to the system main relays.

    [​IMG]
     
    #9 seilerts, Apr 17, 2011
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  10. autotech1100

    autotech1100 New Member

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    Patrick, my Actron only shows the one code, it doesn't show any info codes. I am calling some other shops to see if they have anything to scan it with but so far when I mention that I am working on a Prius they tell me no. Besides the triangle the only other light is the amber ( ! ) and they both pop on at the same time . I know you mentioned earlier that it was a skid control fault, I haven't tried resetting it as of yet. Any chance that could cause the P0AA6? Seilerts, this car belongs to a dealer who bought it at an auction. I did fully charge the 12v on Thursday, it was almost completely dead. It seems to be holding up well but I will charge it again tonight. The connections are the same on my battery as the one you pictured, I double checked that to make sure. I have learned that if I disconnect the 12v battery and pull the service plug from the hybrid battery for a few seconds and reconnect them the car will go into ready mode and start, after a few seconds the triangle and ( ! ) come back. I drove the car about 5 miles with no problems but as soon as you shut it down it won't go back into ready mode unless you disconnect both batteries again. Thanks again to all of you for the help!
     
    #10 autotech1100, Apr 18, 2011
  11. vertex

    vertex Active Member

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    Model:
    Prime Plus
    Here is the description for your code:

    P0AA6-526 Hybrid Battery
    Voltage System
    Isolation Fault
    Insulation
    resistance of
    high voltage
    circuit and body
    is low
    - Frame wire
    - System main
    relay
    - System main
    resistor
    - HV battery
    assembly
    - Electric
    inverter
    compressor
    - Battery ECU
    - HV transaxle
    assembly
    - Inverter with
    converter
    assembly
    - Main battery
    cable
    - No. 2 main
    battery cable
    - Battery plug
    - No. 2 frame
    wire
    - Junction block
    Comes on - DTC stored ​
    ​
    ​
    ​
    HV-421​

    P0AA6-611 Hybrid Battery
    Voltage System
    Isolation Fault
    Insulation
    resistance of A/
    C compressor
    motor or A/C
    inverter is low
    - Electric
    inverter
    compressor
    - Inverter with
    converter
    assembly
    Comes on - DTC stored ​
    ​
    ​
    ​
    HV-421​

    P0AA6-612 Hybrid Battery
    Voltage System
    Isolation Fault
    Insulation
    resistance of
    HV battery,
    battery ECU,
    system main
    relay, or system
    main resistor is
    low
    - HV battery
    assembly
    - Battery ECU
    - System main
    relay
    - System main
    resistor
    - Main battery
    cable
    - No. 2 main
    battery cable
    - Battery plug
    - No. 2 frame
    wire
    - Junction block
    Comes on - DTC stored ​
    ​
    ​
    ​
    HV-421​

    P0AA6-613 Hybrid Battery
    Voltage System
    Isolation Fault
    Insulation
    resistance of
    HV transaxle or
    motor and
    generator
    inverters is low
    - HV transaxle
    assembly
    - Inverter with
    converter
    assembly
    Comes on - DTC stored ​
    ​
    ​
    ​
    HV-421​

    DTC No. Detection Item DTC Detection
    Condition
    Trouble Area Master
    Warning Light
    MIL Memory See page​
    P112 HYBRID VEHICLE CONTROL ​
    ​
    ​
    ​
    ​
    – HYBRID CONTROL SYSTEM HV–79​

    HV​
    P0AA6-614 Hybrid Battery
    Voltage System
    Isolation Fault
    Insulation
    resistance of
    motor and
    generator
    inverters, A/C
    inverter, system
    main relay,
    system main
    resistor, or
    frame wire is
    low
    - Frame wire
    - System main
    relay
    - System main
    resistor​
    -
    HV battery
    assembly
    - Inverter with
    converter
    assembly
    - Main battery
    cable
    - No. 2 main
    battery cable
    - Battery plug
    - No. 2 frame
    wire​
    - Junction block

    As Patrick said, he info code will help narrow down which fault you have.
    The HV battery pack is an area that is inspectable. You could pull the covers off, and look at the wiring on the sides of the packs. If some moisture got in, or a cell leaked and caused corrosion, it could cause this problem, and could be visible. As long as the problem is not the transmission, it is not to bad to fix. If it is the battery pack it may still be under warranty.
     
    #11 vertex, Apr 18, 2011
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  12. autotech1100

    autotech1100 New Member

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    Looks like I may have to take it to a dealer to learn what the info code is. I called a few shops around here and the common response was "We don't work on hybrids". I've been doing light to moderate repair jobs for years and the Prius doesn't seem so bad to me for the most part. A couple years ago I did a hybrid battery upgrade on a 2001 by replacing the cells with ones from a newer battery and the job wasn't bad at all. I really appreciate all of you. The past two days I have driven the car quite a bit and have noticed that during regular driving it does great, the triangle only comes on when you have to sit at a red light or in slow traffic for a while, and then not always. I'm going to call a dealer tomorrow and set up an appointment, I will let you guys know what I find out.
     
    #12 autotech1100, Apr 20, 2011
  13. seilerts

    seilerts Battery Curmudgeon

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    Cool. Note that the three digit info codes are crucial. If all you get back is a report of "P0AA6 replace transaxle," that is entirely not helpful. Many dealership techs either don't know this, or it doesn't make it past the service advisor into the record..
     
    #13 seilerts, Apr 20, 2011
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  14. andyprius

    andyprius Senior Member

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    From the last 4 sentences it really does sound like a stuck relay, the lack of charge to the 12V complicates things even more.
     
    #14 andyprius, Apr 30, 2011
  15. Alan14

    Alan14 New Member

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    I jus got a 2006 Prius from a friend (who doesn't have advice on this) and now it won't start. Same as the following entry: it has a smart key and will get as far as neutral but won't go into reverse or neutral and the brake light comes on and is working....any advice? THANKS!


    from the following I see I am not the only one with this problem....:

     
    #15 Alan14, Dec 18, 2016
  16. JC91006

    JC91006 Senior Member

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    Check the 12v battery
     
    #16 JC91006, Dec 18, 2016
  17. bisco

    bisco cookie crumbler

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    how many miles on her? if it's not the battery, possibly the shifter.
     
    #17 bisco, Dec 18, 2016
  18. JC91006

    JC91006 Senior Member

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    If it's not the battery, then you'll want to return this back to your so called friend.

    No start situations can be very costly to fix in a prius
     
    #18 JC91006, Dec 18, 2016
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