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Master warning, no MIL

Discussion in 'Generation 1 Prius Discussion' started by jonbarril, Oct 27, 2010.

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  1. jonbarril

    jonbarril Junior Member

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    The master waning light came on while I was commuting on the freeway. There was no MIL. I've seen this a month or so ago and, as before, since nothing seemed wrong, I kept going. The last time this happened the warning went away after a day or so. This time it is sticking around. As before, there seems to be no problem with the car -- 80 mile commute, no loss of power, same gas mileage as before. I have a generic ELM327 OBD reader. I tried reading codes but there were none (at least none that it could read since there was no MIL).

    Any suggestions short of bringing it to the dealer?

    BTW: Has anyone found a second source for the Prius Mini-Scanner (or have one they want to sell)? Or, can a regular OBD scanner be trained to read the special prius codes?
     
    #1 jonbarril, Oct 27, 2010
  2. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Read the thread about the ScanGauge?

    Bob Wilson
     
    #2 bwilson4web, Oct 27, 2010
  3. vincent1449p

    vincent1449p Active Member

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    :welcome:

    I can think of 2 possibilities:

    1. Your DTC is pending. MIL will only be set when your DTC is confirmed.

    2. Your DTC is not emission-related. Your ELM327 only read emission-related DTC.

    I have success using ScangaugeII but I think ELM327 can be used too if you know which command to send. If you are willing to try, here are the commands:

    1. Send 07 at the > prompt. This will give you the pending DTC (if any).

    2. Send 13 at the > prompt. This will give you all DTC including those that are not emission-related.

    I had the Master Warning Light before and it turned out to be dirty throttle plate and clogged engine air filter. Bob has a nice writeup here:

    Cleaning Prius Throttle
     
    #3 vincent1449p, Oct 27, 2010
  4. jonbarril

    jonbarril Junior Member

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    Thanks for the replies. I read a (the?) thread about triangle of death and scanguage. The take home message is (perhaps wishful thinking) "keep driving, but keep an eye on it".

    I'll try the manual approach to getting the DTCs, as suggested by vincent1449p.

    BTW: If I were to buy (yet) another scanner, is ScanGuage the best one to get for a Gen I prius? Also, I see folks talking about modifying the OBD cable. Will that work for a generic scanner (such as mine)? Is it necessary to mod the cable just to get the DTC codes (as was suggested)?
     
    #4 jonbarril, Oct 28, 2010
  5. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Scanners come with a price-performance ratio:
    Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7
    0 price performance product
    1 $50-120 emission data and code risk of ISO-9141 spike over the counter scanners
    2 $150-175 emissions HV and battery ECU adapter for ISO-9141 to prevent spiking the brake ECU no data recording ScanGauge II with ability to add XGAUGE for other ECUs extensive HV and battery ECU coverage
    3 $150 deposit $15/mo rental HV battery and ICE ECU and ~50 data points and recording via RS-232 no longer in production I have two available for rental
    4 $400 plus laptop all but security ECU rotten support and known data errors recording built-in works best with pig-tail to avoid ISO-9141 spike Auto Enginuity
    5 $1 200-1 500 plus laptop reported complete coverage Tech Stream Lite
    Our NHW11 uses ISO-9141 but uses one of the CANbus signals for Tc/Ts. What this means is a generic scanner that attempts to probe the CANbus signals can spike the Tc/Ts line and induce false error codes.

    The cable modification limits the signals from the scanner to just power and the ISO-9141 signals, the L and K data lines. Our NHW11 maps another signal from the Tc/Ts pair to one of the OBD data pins. If a scanner tickles the Tc/Ts pair, it can induce false codes, usually in the brake ECU. But Vincent added a neat trick, a diode and 9 V battery for the ScanGauge.

    The ScanGauge can be programmed to add extra data displays using the XGAUGE option. However, it does this only after initialization, the process that the scanner 'connects' to the control computers. Vincent's trick allows the ScanGauge to stay powered up after initialization and bringing into the house to hook up to a 12 V power supply. Then extra XGAUGEs can be programmed without having sit in the car.

    Bob Wilson
     
    #5 bwilson4web, Oct 28, 2010
  6. jonbarril

    jonbarril Junior Member

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    I did as you suggested, and this is the result:

    07:
    48 6B 10 47 00 00 00 00 00 00 0A
    48 6B D5 47 00 00 00 00 00 00 CF
    13:
    48 6B 10 53 00 00 00 00 00 00 16


    I'm new to DTC, so I am unclear as to what I am looking at (I was expecting "P" numbers, not hex groups -- oh well). I googled around a bit but couldn't find anything about these specific responses.

    --jon
     
    #6 jonbarril, Oct 28, 2010
  7. jonbarril

    jonbarril Junior Member

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    Bob, thanks for the excellent information about the scanners and the cable mod. If I can't get anywhere via raw DTC then the ScanGuage might an inexpensive next step.

    --jon
     
    #7 jonbarril, Oct 28, 2010
  8. jk450

    jk450 New Member

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    The Gen I Prius does not use the CAN protocol.
     
    #8 jk450, Oct 28, 2010
  9. rjghah

    rjghah New Member

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    Check the threads on power inverter. When this happened to me, the dealer said the power inverter coolant pump had failed which had ruined the power inverter ($7,000 repair!). Similar stories all over the web, both Prius and Highlander. Toyota knows about the problem but the public does not.



     
    #9 rjghah, Oct 28, 2010
  10. vincent1449p

    vincent1449p Active Member

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    These are raw data, P codes are decoded by software.

    Below are the breakdown:

    48 6B : Std response to ISO 9141 68 6A functional request.

    10, D5 : ECUs that responded; ECM and Bty ECU respectively.

    47, 53 : Normal response to mode 07 and 13 respectively.

    00 00 00 00 00 00 : 3 sets of DTCs, 00 00 means no DTC detected.

    0A, CF & 16 : Checksum.

    I don't see any response from HV ECU, 16. Have you tried sending the command a few times? Sometimes, some ECU may not response in time if there are other ECU responding. Alternatively, you may use physical addressing to target at a specific ECU.

    > AT SH 81 16 F1 (Set Headers for HV ECU)

    Then try the 07 and 13 again. Please remember to reset to default using AT D after this.
     
    #10 vincent1449p, Oct 28, 2010
  11. jonbarril

    jonbarril Junior Member

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    I tried again and made some notes.

    When I connect the app finds 3 ECUs: 10 with 19 pids, 16 with 10 pids, and D5 with 5 pids.

    I repeated the following after selecting each of these ECUs. The results were the same regardless of the ECU I selected at connection time.

    Trying 07 and 13 several times, each time selecting a different ECU, produced the same result as I reported earlier.

    07:
    48 6B 10 47 00 00 00 00 00 00 0A
    48 6B D5 47 00 00 00 00 00 00 CF
    13:
    48 6B 10 53 00 00 00 00 00 00 16

    When I tried "AT SH 81 16 F1", the response was "OK", and then a few seconds later a dialog appeared saying that a communication error occurred with the ECU, and the connection was lost. Trying several times, each time selecting a different ECU, produced the same result. I tried typing 07 and 13 very quickly, but the answer was NO DATA.
     
    #11 jonbarril, Oct 29, 2010
  12. jonbarril

    jonbarril Junior Member

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    (It looks like my earlier post did not go through....)

    Which inverter threads are you referring to? Electrical or coolant? Should I look for corrosion, a loose connection, leakage, etc.?

    --jon
     
    #12 jonbarril, Oct 29, 2010
  13. vincent1449p

    vincent1449p Active Member

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    Thanks, it seems like HV ECU is not responding. Can you try to set the timeout to maximum?

    > AT ST FF

    This will let ELM327 to wait for a response for the maximum time before declaring no data.

    Could you check what is the protocol it is connected?

    > AT DP

    I suspect it is ISO 9141-2 because of the 48 6B response. If yes, you can try to change protocol to see if it helps.

    > AT TP A4 or AT TP A5
     
    #13 vincent1449p, Oct 29, 2010
  14. jonbarril

    jonbarril Junior Member

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    "AT DP" - Said the protocol is ISO 9141-2.
    "AT TP A4" and "AT TP A5" - Both caused disconnect.
    "AT ST FF" and then "AT SH 81 16 F1" - Still causes disconnect.

    Anything else to try? Would help to buy and try a ScanGuage? Is it time to bite the bullet and bring it to the dealer?
     
    #14 jonbarril, Oct 30, 2010
  15. jonbarril

    jonbarril Junior Member

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    Problem solved!

    I finally figured out where the inverter coolant reservoir was and checked it. I saw turbulence, but noticed that the level was at the low mark. I added just a little water to it and bingo, the master warning light went off.

    Of course, the question as to why I could not get the codes from the computer is another matter.

    --jon
     
    #15 jonbarril, Oct 30, 2010
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  16. vincent1449p

    vincent1449p Active Member

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    It seems like ELM always disconnects if you sent a KWP command to an ISO 9141-2 connection. It also checks the KeyWords and determine that it is not KWP2000 so the initialization also fails. The Scangauge do not have these checks.

    One last thing to try is to disable KW checking and fool the ELM it is connected to KWP2000:

    > AT KW0
    > AT TP A4
    > AT SH 81 16 F1
     
    #16 vincent1449p, Oct 30, 2010
  17. vincent1449p

    vincent1449p Active Member

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    I just found the physical addressing for ISO 9141-2. If KWP2000 doesn't work, you can try this:

    > AT D (reset to Defaults)
    > AT SH 6C 16 F1
    > 13
     
    #17 vincent1449p, Oct 31, 2010
  18. tochatihu

    tochatihu Senior Member

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    Jonbarril, please continue to monitor the inverter coolant level in that reservoir.
     
    #18 tochatihu, Oct 31, 2010
  19. jonbarril

    jonbarril Junior Member

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    Success was short lived:-(

    I started the car this morning to start my commute and, once the engine warmed up the master warning light came on again, and has stayed on in spite of repeated restarts. I didn't have a chance to check the coolant level again -- thanks, tochatihu, for the reminder.

    I did try,

    > AT KW0
    > AT TP A4

    "AT TP A4" caused a disconnect. I didn't get a chance to try your second suggestion -- I'll try this evening.
     
    #19 jonbarril, Nov 1, 2010
  20. jonbarril

    jonbarril Junior Member

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    Unfortunately this didn't work either. "AT D" causes a disconnect. In looking through the log, at startup the software tries several protocols and settles on ISO 9141-2. My guess is that the default protocol is incompatible with the prius, hence the "AT D" causes a disconnect.
     
    #20 jonbarril, Nov 2, 2010
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