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2004 Prius dash lit up like a Christmas tree

Discussion in 'Gen 2 Prius Technical Discussion' started by Dustin92, Mar 18, 2021.

  1. Dustin92

    Dustin92 Junior Member

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    I have a 2004 Prius with 245k on the clock.. Hybrid battery was replaced with a used one at 205k.. Battery currently has 205k.. Has not had any other repairs that I know of/related. I left work tonight and as I'm pulling out of the parking lot I get an audible constant beep, red triangle, brake,abs,vsc, red car with an exclamation point on the screen, and "problem" across the screen. Also got another audible beep intermittently, didn't feel like I was getting any regen when braking. I stopped at a friend's house and when I pulled in the driveway it went into neutral. I had to hold power button to reset and was able to drive it home. Still have red triangle and red car on the screen. Any ideas? Has been super relaible since I bought it with 174k and I was hoping for the quarter million.. Any advice is helpful!

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  2. ChapmanF

    ChapmanF Senior Member

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    Please post the trouble codes here. If you don't have a scan tool to read them, you can search here for how to read the brake trouble codes by counting light blinks, then post what you find.
     
  3. Dustin92

    Dustin92 Junior Member

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    Alright.. I don't have a code reader but I will figure out how to do that when I get up in the morning. I'm not feeling like it's a brake issue to be honest, front pads/rotors are a couple years old, rear shoes are maybe 6 months old. I was definitely getting braking but felt like just the friction brakes, no or little regen. After I restarted the car and all I had was the red triangle and red car, it felt pretty normal but maybe a little low on power.

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  4. ChapmanF

    ChapmanF Senior Member

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    Out of the couple hundred different issues the brake computer is able to report through trouble codes, precisely zero of them are about the age of the pads, rotors, or shoes. (Those are still things to check visually now and then, just like the old days.)
     
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  5. Dustin92

    Dustin92 Junior Member

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    Just adding what I know.. Pads/rotors/shoes are good and I do hear the brake pump engaging. I haven't checked anything under the hood (fluid levels etc.) yet, it was dark when I got home. I'll figure out the trouble codes if any are present in the morning and report back.

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  6. Dustin92

    Dustin92 Junior Member

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    Can anyone point me in he right direction for reading the codes? I have spent about 45 mins searching and all I can find is posts referencing how it can be done, but none telling how to actually do it.
    On another note I did go out to the car this morning and checked fluids, all are fine, nothing visibly leaking. I checked the battery voltage with the on screen dignostic menu and I have 11.8 with engine off, igntion on, and 13.1 in ready mode.
    Only dash lights I have today are the red triangle and red car on the mfd screen. Hybrid battery level looks normal. I have not tried to drive it today.

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  7. ChapmanF

    ChapmanF Senior Member

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    Here's an old post describing it for Gen 1. The basics don't change, but a few details do, like Gen 2 has different ECUs and they don't all know how to play the blinky game. The brake ECU still does though.

    The brake ECU is responsible for more than one light on the dash: ((!)), ABS, VSC. It can blink codes on all of them. Be sure to focus on one light at a time and keep straight which codes were blinked on which light. Some of the two-digit code numbers overlap, and on the different lights they mean different things.
     
  8. Dustin92

    Dustin92 Junior Member

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    Which pins do I need to jump though? I see on the other post which numbers but they are not numbered on the car.. And same as that post, I don't want to short something out..

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  9. dolj

    dolj Senior Member

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    Pins 4 (CG) and 13 (TC).
    Prius OBD2 port.jpg
     
  10. Dustin92

    Dustin92 Junior Member

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    Thank You! I'll go out and do that now! Just the diagram I was looking for!

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  11. Dustin92

    Dustin92 Junior Member

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    I'm getting 42 on the abs light and 42 on the ((!)) Light. Brake solid on. Airbag light flashes continuously.

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  12. ChapmanF

    ChapmanF Senior Member

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    42 on the ABS light is easy, it just means "what are you looking at me for? go read the ECB code!"

    42 on the ((!)) (a/k/a ECB) light is the same as diagnostic code C1242 and means you've got some kind of intermittent or bad connection in the electrical power supplying your Skid Control ECU (despite the name, that's the ECU that handles all your braking, ABS, and skid control).

    The skid ECU is kind of built in two redundant sections, and they get their power separately: there's an IG1 terminal and an IG2 terminal that should both get power when the car is on. IG1 is supplied through the IG1 relay and the AM1 fuse, and IG2 is supplied (wait for it) through the IG2 relay and AM2 fuse.

    The code you're getting means there was a period of at least four seconds where the skid ECU saw power either at IG1 but not at IG2, or at IG2 but not at IG1. (There is even an INF code you could read, if you had a scan tool, that would tell you which case: 87 for power at IG2 but not IG1, 88 for IG1 but not IG2.)

    There are eight pages in the Repair Manual (more info) that will step you through the various checks of relays and wiring that would get you to the bottom of the issue.