Setting Cruise Control Triggers Engine Light

Discussion in 'Generation 1 Prius Discussion' started by Bruce Berquist, Sep 29, 2021.

  1. Bruce Berquist

    Bruce Berquist New Member

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    Okay. New issue to troubleshoot and repair.
    My 2003 Sedan sat for a very long time before I purchased it, and I decided to make a fun and educational project of restoring it.

    Repaired p3030 HV battery trouble by replacing 2 bad cells and replacing the contact rails, but now am getting p3006 SOC unbalanced state of charge.
    The car is running great and the battery is charging and discharging properly so I'm not worrying for now.

    Replaced the exhaust and checked all emissions fittings valves switches and relays.

    Passed inspection.

    HERE'S THE NEW ISSUE:
    When I set the cruise control the engine light will come on and cruise control will stop working. This does not happen immediately but does in about 3 to 5 miles.

    With cruise control off engine light never comes on.

    No trouble codes come up (except for the p3006 battery code)

    Car runs great!

    Where should I look to find, diagnose and repair this cruise control problem?
     
    #1 Bruce Berquist, Sep 29, 2021
    Last edited: Sep 29, 2021
  2. ChapmanF

    ChapmanF Senior Member

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    Not sure about the cruise issue, but are you sure this code was transcribed right?

    P3009 has nothing to do with unbalanced state of charge. It's a high voltage insulation fault.

    P3006, now that's an unbalanced SoC code.
     
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  3. Bruce Berquist

    Bruce Berquist New Member

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  4. AlexY

    AlexY Member

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    For those 3-5 miles CC does maintain speed as expected? There should be code if engine light is coming on, you need techstream and proper cable to read all computers.
     
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  5. Bruce Berquist

    Bruce Berquist New Member

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    The cruise control maintains the speed perfectly for the first few miles then it shuts off with the engine light.

    Once again, if there is a code it has to be related with the cruise control in some way since the engine light never comes on when the cruise control is turned off.

    The engine light comes on only after a few miles on cruise control and never at any other time.

    What is the cruise control connected with that might be triggered with the added load of cruise control?

    Or what failure in cruise control can trigger the engine light?
     
  6. dolj

    dolj Senior Member

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    If the only code you have is P3006, then it follows that it is material to your CC disengaging and switching off. How or why I can't tell you, but looking to the repair manual will – as well as giving you information about how the cruise system works.

    What code reader are you using and how confident are you are seeing all codes that are potentially present?

    For the Gen 2 the repair manual says this about the Cruise Control System Operation Control:

    When the cruise control ECU which is built into the HV (hybrid vehicle) control ECU receives a cruise control switch signal, it calculates the cruise control request value, and calculates the motive forces of the engine, MG1, and MG2 to achieve an optimal combination.

    Whether it works the same way in the Gen 1, I couldn't say but others experienced with the Gen 1 could. I mention it just to illustrate how the repair manual could be helpful.
     
  7. AlexY

    AlexY Member

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    Unfortunately not, CC is just a software feature built in to HV ECU, it can be turned off at any time car think something is wrong, I'm surprised you can activate it at all but 1-st gen have quite huge delays in triggering any errors and is very tolerant to run with issues.
    Unfortunately my gen-1 is off the road so I can't confirm if unbalanced battery can trigger it, mine is 50% delta SOC and I think it was throwing P3006 because of that.
     
  8. Bruce Berquist

    Bruce Berquist New Member

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    I don't have the code at the top of my mind right now but I changed my OBDII software to a premium pro version and am getting an ABS code that I have discovered is related to cruise control and to the battery.

    Turns out that a skip or a sudden drop in voltage can trigger an engine light and the loss of ABS and/or cruise control too.
    So yes, this trouble can be triggered by uneven SOC or other battery trouble.

    Fortunately, my Prius is otherwise running like a well tuned top. There are no engine DTC codes nor any other ECUs with DTC codes other than the one battery code and the one ABS code, so I am now going to diagnose whether I would prefer to replace the 2 lower voltage sells in module 19 or whether it is time to shop for another HV battery.

    Thank you for your input on this.
     
  9. dolj

    dolj Senior Member

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    Just bear in mind that you cannot replace individuals cells (there are 6 cells to a module) as modules are sealed units. Your battery is made up of 38 modules grouped into 19 blocks of two modules which is the unit that is monitored by the battery ECU.

    The path that might make the most sense, assuming your car is in pristine condition and worth preserving for up to 10 more years, is to try and procure two Prius c batteries (or 2 4th Gen Prius (NiMH) batteries, or some combination of the 2) from a car written off in the last 2 - 3 years and replace all the modules in your current battery with the modules from the wrecked cars.

    You will have 2 or more modules left over that you can sell off plus all the bits and the cases to recover some money. You probably would even be able to sell the original Gen 1 modules to someone even if only to a recycler.
     
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  10. Bruce Berquist

    Bruce Berquist New Member

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    A lot of references refer to what you call modules as cells and what you call blocks as modules.

    A module is made up of 2 cells and a block is made up of a set of modules.
    The modules are monitored for voltage performance and the blocks are monitored for temperature and voltage.

    Either way, we know what each other are talking about.

    I have been shopping for either 2 replacement gen 1 cells but am concerned that that might be only a short term fix if other cells are on the edge for failure too.

    I have been shopping for sets of cells and have even been considering some of the alternative designs such as cylindrical cells.
    Would love to find some new tech with faster charging capabilities and longer discharge performance, if that is available out there somewhere.
     
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