Need help Warning lights on

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Josephphamy, Mar 2, 2017.

  1. ChapmanF

    ChapmanF Senior Member

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    What Patrick was getting at, the two screenshots you posted in #14 are, one from the ABS/VSC/TRAC computer (ECU), and one from the Gateway ECU. (You can see those names in the tabs near the top of the screen).

    If you just run a Techstream 'health check', you should get back a whole list of ECUs and whether they have any active codes or not.

    In your screenshots, the first one, from the brake computer, is just telling you that it has heard of some problem from the HV computer. Those two computers have to share information, because if the HV one is having some problem, the brake computer has to know it might be on its own to slow the car down without regenerative help. So it has those two codes, but they are pretty vague. All they mean is "hey, I'm the brake computer, and I've heard the HV computer mention there's some problem."

    So to track down the problem, you need to check the other ECUs that are showing codes in Techstream. (Don't be too strict about the names of the ECUs ... the one that basically coordinates the powertrain was called "HV ECU" in Gen 1, they haven't used the exact same name in all gens, could be called something like Hybrid or Power Control, I don't have the books in front of me right now.)

    Your second screen shot is from the Gateway ECU (as its name suggests, it sits at the junction of some different comm networks in the car, and passes data between them), and all three of those codes are showing trouble communicating with three different other components in the car.

    Those codes might be clearable (try asking Techstream to clear them). Sometimes, connecting odd scantools or devices to the OBD port can cause comm errors to be logged, and you can clear them once the offending devices aren't connected.

    -Chap
     
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  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Maybe the DTC from the "important" ECU's are not visible to the OP because of the comm faults...
     
  3. ChapmanF

    ChapmanF Senior Member

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    The Gateway ECU seemed to be complaining only about the Body, Smart Key, and Combination Meter ECUs.

    A Gen 2 has three types of network: the CAN, the BEAN, and the AVC-LAN; the Gateway ECU has an interface on all three (2004 New Car Features, p. BE-47). The Body, Smart, and Meter ECUs are all on the BEAN (p. BE-49). The HV and battery ECUs are both on the CAN (p. BE-48), which has its own direct connections to the DLC connector, so the reported comm errors shouldn't be interfering with talking to them.

    So, I'm not sure why the OP isn't seeing those codes. Maybe just spend a bit more time getting familiar with Techstream?

    Also not sure yet what might explain those particular three BEAN denizens not showing up. The BEAN is a ring network, intended to stay functional even with any one break. Page BE-49 shows where those ECUs are, logically, around the ring, and they aren't all three adjacent, scuttling my easiest guess. Back to the drawing board....

    -Chap
     
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