Red triangle of death only when turning on headlights

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by beday beday, Jun 1, 2020.

  1. beday beday

    beday beday New Member

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    Hello the people of Prius chat, I am new to prius. I purchased a gen2 w/nav with 156k recently. Car was working fine for a couple of month avaraging 35-40mpg but suddenly it has developed a red triangle light show. I have searched the forum for answers but i could not find one that answered this unique issure that i'm having. and here at it....

    The red triangle comes on with VSC and ( ! ) lights only when turning headlights on and stays on during runing even when headlights are off but, it goes off when restarting the car. i could drive miles without the lights coming on unless i turn the lights on. i have checked all the fuses.

    HELP!!!!!!!
     
    #1 beday beday, Jun 1, 2020
  2. SFO

    SFO Senior Member

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    Welcome to PriusChat!!

    Happen to have any OBD2 codes (DTCs) that you can share with us?
     
    #2 SFO, Jun 1, 2020
  3. beday beday

    beday beday New Member

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    I ran 'faulty codes' on Torque pro but nothing came up. This is when the warning lights were on the dash. What's weird is, even though no codes come up, when i use the "clear codes" function, it clears the lights but the come back as soon as I turn on the headlights.
    I will take it to a shop as soon as I get the tabs updated ( which i couldn't do this past couple of month due to DMV being closed).
     
    #3 beday beday, Jun 2, 2020
  4. SFO

    SFO Senior Member

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    You may need to load extra Gen2 specific PIDs into Torque, or try using a different app like Dr Prius or Hybrid Assistant.

    CA state troopers aren't currently enforcing tabs as our DMV is also closed, check and see if this might also apply in your state as well.
     
    #4 SFO, Jun 2, 2020
  5. TMR-JWAP

    TMR-JWAP Senior Member

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    I'm definitely following this thread. Reminds me of a 1978 Ford Grenade (Grenada) that would stall the engine if the headlights were turned on below ~25 mph.

    Do you have HID lights or Halogen? (if you have OEM fog lights, you have HID, no foglights = halogen headlights)
    Are the headlights the correct OEM recommended bulbs for the car or do you have an "upgraded" aftermarket high power bulb?

    If you unplug one headlight does the RTOD still come on?
    What if you unplug both headlights?
    Just curious if it's current load related or just switch position related.

    Take a look at the headlight plugs anyway, I've seen many that get significant heat damage and the plastic just crumbles away.

    Throwing ideas to see what sticks!!
     
    #5 TMR-JWAP, Jun 2, 2020
  6. beday beday

    beday beday New Member

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    I download prius doctor. I'm getting code P0A08

    So need new batteries?
     
    #6 beday beday, Jun 5, 2020
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  7. bisco

    bisco cookie crumbler

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    12v?
     
    #7 bisco, Jun 5, 2020
  8. edthefox5

    edthefox5 Senior Member

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    #8 edthefox5, Jun 5, 2020
  9. TMR-JWAP

    TMR-JWAP Senior Member

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    NO. Verify whether you have P0a08 which is a DC/DC converter problem, or P0A80, which is the HV Battery problem.

    Makes more sense that it's a P0A08, as that is the 12v circuit of the HV System. This portion of the circuit acts similar to the alternator of a normal car. Once the car is in READY, the DC/DC Converter converts 210v HV System power to ~13.7-14 volts to power the 12v system.

    DESCRIPTION The HV Control ECU monitors the DC / DC converter circuit status via the NODD terminal. If the ECU detects an internal circuit malfunction in the converter and stops converter operation with its fail-safe function, causing the auxiliary battery voltage to drop below 11 V, the ECU outputs DTC P0A08 (INF 264).

    P0A08.jpg
     
    #9 TMR-JWAP, Jun 5, 2020
    Last edited: Jun 5, 2020
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  10. dolj

    dolj Senior Member

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    What TMR-JWAP said.
     
    #10 dolj, Jun 6, 2020
  11. beday beday

    beday beday New Member

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    It is P0A08 sadly. I makes sense that It'd only come one when the headlights are on because they draw so much power and it's sensing it's not charging the 12v as fast as it's draining it?

    I ordered a fuse relay box for the 12v just in case that's the problem too. I read somewhere on the internet a faulty one of those can also give you that code. Trying all inexpensive options before I get the battery replaced.
     
    #11 beday beday, Jun 7, 2020
  12. SFO

    SFO Senior Member

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    #12 SFO, Jun 8, 2020
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  13. dolj

    dolj Senior Member

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    It is not necessarily sadly. P0A08 is a problem in your inverter, not your HV battery.
    That is 5th in the table below. Check the preceding four items before just jumping in there. Excluding the HV Control ECU, there are other inexpensive options to rule out.
    ... in the repair manual for the 2004. The attached workup for the 2006 has a bit more to do.

    Perform the Inspection Procedure for P0A08 to work out what needs to be done.

    DTC No. Detection Item DTC Detection Condition Trouble Area Master Warning Light MIL Memory
    1 P0A08-264 DC / DC Converter Status Circuit DC / DC converter malfunction
    • Auxiliary battery
    • Fusible link block assembly
    • HV control ECU
    • Fuse (for 12 V electrical equipment)
    • Engine room relay block
    • Inverter cooling hose
    • Water pump with motor assembly
    • Cooling fan motor
    • No.2 cooling fan motor
    • Wire harness or connector
    • Inverter with converter assembly (DC / DC converter)
    		 Comes on Stays Off DTC stored


    The Inspection Procedure for DTC P0A08 is attached.
     

    Attached Files:

    #13 dolj, Jun 8, 2020
    Last edited: Jun 8, 2020
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  14. beday beday

    beday beday New Member

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    Thank you for all the info!

    I changed 12v battery about 3 month a month ago when i Purchased the car and it is testing 12-13volt.
    I also changed the DC to DC fusable link assembly due to a reverse jump before i ended up replacing the 12v battery.
    HV control ECU - I'm not sure what this is really. I know a little about these cars and I think I should probably just take it to the shop if the new 12v fuse assembly doesn't change my situation.

    Thank you guys for all your help!!!1
     
    #14 beday beday, Jun 8, 2020
  15. beday beday

    beday beday New Member

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    Headlight Beam Level Control
    This system adjusts the illuminating angle from changes in the vehicle height and axle distance, based on the information of the vehicle height detected by the height sensors installed at the rear of the vehicle and on information of the vehicle speed and acceleration output from the VSC system which operates the reflector with the obtained illuminating angle through actuators in order to always keep the beam axis constant. If an error occurs in this system, the headlight beam level control warning light in the combination meter lights up and warning buzzer goes on to warn the driver."



    I found the above underlined info on the Prius electrical wiring diagram. Do you guys think this is what's going on as it indicates the VSC system somehow is connected to the headlight? This is driving me nuts lol
     
    #15 beday beday, Jun 8, 2020
  16. dolj

    dolj Senior Member

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    No.
     
    #16 dolj, Jun 8, 2020
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