2001 Warning Lights, cannot retrieve codes

Discussion in 'Generation 1 Prius Discussion' started by beth524, Aug 31, 2021.

  1. beth524

    beth524 Junior Member

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    The exclamation point triangle, check engine light, and car with exclamation point came on when I started my car last week. I tried 2 code readers (at auto parts stores) and they both found no codes. I replaced the 12 volt battery and the warning lights came on again instantly. Cleaned the throttle body and maf sensor. No difference. The car runs fine, the inverter fluid is flowing, and I wonder why no codes can be read. I am hoping it is not the hybrid battery. The car has 77,000 miles on it. Any suggestions? Also, I live in a small city and our Toyota dealer is a crook.
     
  2. dolj

    dolj Senior Member

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    If you really did have only the "check engine" light and master warming light ("exclamation point triangle") on, I'm surprised you did not get at least engine codes. Even the most generic reader should be able to show those.

    If by 'check engine light' you mean any amount of the other warning lights, that might be not so surprising.

    There are a lot of generic readers that can access and read no more than 2 or three of the available ECUs.

    The key thing is to use a reader that is capable of reading all the ECUs. Only then will you get the full picture.
     
  3. WHCSC

    WHCSC Member

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    Search Techstream on here for more info on reading the codes and subcodes
     
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  4. beth524

    beth524 Junior Member

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    I was always able to see at least a few codes on my last 2002 Prius. This seems odd to me. And the dealer in town cannot see me for at least 2 weeks! The car has no noticeable performance issues-drives perfectly. Even after I clear the waring lights, they come back on immediately.
     
  5. ChapmanF

    ChapmanF Senior Member

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    In Gen 1, many of the ECUs in the car have a fallback ability to blink out their trouble codes on the dash lights, in case you aren't getting access with a code reader. Even in Gen 2 and Gen 3 some of the ECUs still have that ability, but many of them did in Gen 1. You connect pins 4 and 13 (CG and Tc) at the diagnostic port with a short skinny wire, turn the key to the ON notch, and watch the cacophony of blinking lights on the dash. (To count out the codes, you have to focus on one light at a time and tune out all the blinks from the others.)

    That way you can at least find some of the codes you have. Disappointingly, the HV ECU and the battery ECU do not have code-blinking fallbacks, so a code reader is the only way of finding out what they've got to say.

    Gen 1 was designed before CAN became the big successful car networking technology, and all the computers in a Gen 1 are connected by a real hodge-podge of networking technologies, sometimes even using different protocols or bit rates over the same wires. Some of them Techstream may only communicate with by relaying messages through others.

    In some cases where lights are on but codes aren't read, there really is a communication error somewhere that is preventing the code reader from reaching the ECU that has the codes. In that case, the blink codes you get might include some communication error codes that might confirm it's that kind of problem. Then that would call for a look at the network diagrams in the repair manual and wiring diagram to see where the communication breakdown might be, depending on the available information of what things can't see what other things.
     
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  6. mroberds

    mroberds Member

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    +1 for Techstream. You need a "mini-VCI" cable from Amazon for $30ish, some software, and a Windows PC or laptop. When I set myself up for Techstream a couple of years ago, this is what I did: Attempting to get our original 01 Prius back on the road | PriusChat
    That setup was with 32-bit Windows; I have since set it up on 64-bit Windows but there are a couple of extra steps.
     
  7. mroberds

    mroberds Member

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    I have had the same problem in a non-automotive context: one blinkenlight that I needed to count, near some other blinkenlights that I needed to ignore. A relatively opaque piece of material that you can easily cut with scissors (a cereal box works great) is helpful to mask off the blinkenlights you don't care about.
     
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