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Skid Control Module Revisited... Again

Discussion in 'Gen 2 Prius Technical Discussion' started by yaoaoatgyf, May 11, 2018.

  1. yaoaoatgyf

    yaoaoatgyf Member

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    Did a few searches and found multiple threads on the Skid Control module.

    Developed an odd problem on our 2007 Prius. 204k miles. I bought this car super cheap because it needed a new hybrid battery. Put in a new one from Toyota and have had zero problems since.... until now. Well, not really zero problems. The tire pressure monitor light flashes when starting up and then stays on. I am certain non of the senders have ever been replaced, and the batteries are dead at 11 years old. No big deal. I check tire pressure regularly, as I do on all our cars (13 at present). Put on four new tires, and have changed oil twice. Does not use any oil between changes (at least not enough to add any).

    Anyway, on to the current issue. Last week, my wife reported that the brake light (red one that indicates the park brake is on) and the brake warning light and the abs light and the VSC light all came one. Next time we drove it, no issue. When backing up one day late last week, and with my foot lightly on the brake, it felt like I ran into something, but there was nothing behind the car. Hmmm. Happened two times. Next thing you know, the four (4) lights mentioned above all come on and stay on. Checked the 12 volt after letting it sit all night. 12.7 volts. I is only 14 mos old, so I figured it was OK, and that test confirmed it. 13.81 when in "Ready" mode.

    Pulled the wheels and looked at the brakes. Nothing loose that would cause them to suddeny lock up.

    Checked the blinking codes: ABS: 42 Brake: 41, 57, 69. No VSC code. The lights had never come on until last week. I figured with that many codes, and after reading the threads I could find on the subject, that it was most likely the skid control module. Found one for $26.04 with free shipping. I normally don't just throw parts at cars, but with my limited knowledge of the Prius, and no previous experience, figured a $26 venture was worth a shot. Swapped it out this evening after disconnecting the battery. Once you figure out where everything is, it takes about 30 minutes. Started the car and the park brake light did not come on, but the other three did. Drove the car a few miles, and checked the codes.

    Brake: 36, ABS: 95, VSC 43, 62, 63. Hmm. At least the park brake light went off.

    Drove it again. It runs fine, accellerates fine, brakes fine and makes no weird noises. I backed up multiple times with my foot covering the brake (same technique that resulted in the sudden brake lock) and could not get it to act up. No sypmtoms. I suspect my original Skid control went south. I also suspect the one I bought has already given up the ghost. No two codes in common.

    Anyone with any real life experience on the Gen2 skid control? Please don't tell me to replace the 12v as a precaution. It is fine.

    Is it possible to erase the blinking trouble codes? If so, how:? I noticed a diagnostic screen came up on the display panel when I jumped 4 and 13 contacts. I have a generic OBDII scanner, but of course, it does not read the skid control module codes.

    Any help is appreciated.

    Lynn
     
  2. fotomoto

    fotomoto Senior Member

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    If you don't have the diagnostic tools to do it, just disconnect the 12v battery for a few minutes.
     
  3. dolj

    dolj Senior Member

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    That won't erase ABS codes. There is a manual procedure to clear codes, but the OP will have to use the search function to find it. Not sure of good search terms to use though. If the PC search above doesn't find anything useful use Google to search the site:

    Code:
    site:priuschat.com "Gen 2" Press brake pedal 8 times in 5 seconds clear code without scan tool
    Using that search I found this thread:

    How do you reset ABS light & yellow ((!)) ? | PriusChat | Post #7

    Hope that helps.
     
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  4. ChapmanF

    ChapmanF Senior Member

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    Have you looked up what any of those codes mean yet?

    I don't have a Gen 2 Repair Manual in front of me at the moment. Some of the possible codes (I don't have them memorized, though) have to do with calibrations that need to be learned ... transplanting some other car's skid ECU to control your car's actuator valves might plausibly raise some of those sorts of codes, until you put it through the learning process. But it'll be much easier to think about after looking them up.

    Cheers,
    -Chap
     
  5. rmacguy1949

    rmacguy1949 Junior Member

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    When this same thing happened it was the brake actuator, sorry
     
  6. dolj

    dolj Senior Member

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    None of those codes seem to tie up with the system stated.

    Attached are the codes for the ABS, VSC and ECB from the 2006 repair manual. The 2007 should be the same.

    The blink code is the /xx after the Pxxxx.
     

    Attached Files:

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  7. NortTexSalv04Prius

    NortTexSalv04Prius Active Member

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    FYI

    The VSC,ABS, (()) , skid control in my first hand experience are PIA
    having said that

    I can set the skid control of just by being on a bumpy freaking roadway...
    the sensor threshold is real low to trigger
     
  8. yaoaoatgyf

    yaoaoatgyf Member

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    dolj: Thanks for posting the codes. Can't seem to find code 36 for the brake (assuming that is EBC). There is a 36 for the ABS, but not the brake.

    Chap, when you say: "until you put it through the learning process" what does that refer to?
    Are you saying just driving the car?

    Have looked up codes, but so far haven't seen any matches. I suspect this unit is bad. I found the procedure for resetting ABS codes, and will try that first.

    Thanks.
     
  9. ChapmanF

    ChapmanF Senior Member

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    It's curious that the codes aren't matching dolj's 2006 Repair Manual; I wouldn't think one year difference in the same generation would lead to such a discrepancy. I did reply on one person's thread once where it was clear they had been one digit off when grouping the two digit codes, so the car was saying (for example) 12 34 56 but they posted 23 45 61. (The pause between digits is a tad bit longer in between the groups.)

    At this point, I'd be interested to see what 5-character codes an actual Techstream rig reports, and then look back in the manual to see what 2-digit blink codes those were supposed to be, and maybe figure out why they didn't seem to match.

    As for the various learning processes, those are all in the manual too, along with the resetting procedure you found. I'm thinking of the following codes (which might not be among the ones you have, but just for exposition's sake): VSC C1210/36, VSC C1336/39, ECB C1345/66, ECB C1392/48.

    If you had any of those codes, it would mean that the corresponding parameters need to be learned by the ECU. There are procedures in the repair manual for how to tell it to go learn each one, with the special requirements for each one (for example, you don't want to tell it to learn the acceleration zero point when you're parked on a grade!).

    One I've done before was the linear solenoid offset; you make sure you're parked level and trigger the procedure to start, and the car sits for a minute or two going click-pfsst, click-Pfsst, click-PFsst, click-PFSst, click-PFSSt, click-PFSST, and then it's all learned and ready to go.

    -Chap
     
  10. yaoaoatgyf

    yaoaoatgyf Member

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    Tried a second skid control module. Found the procedure to reset (erase) the codes. Put the car in "ready" mode, and all three of the aformentioned lights come on within a couple of seconds, even without depressing the brake, or taking the car out of park.
    The red "brake" light only comes on when the park brake is set, as it should.
    Put this on the back burner for a while, as we don't need to drive the car often. I have been using it just for short errands in town (we live in a small town). It runs and drives and brakes just fine.
    Really torn between replacing the brake actuator or just driving it as it is. I don't like not having any warning system. The car has not had the sudden unexpected stop in reverse since my first post. I can get a used brake actuator for about $250 shipped. I don't mind doing the work. I am guessing there is no assurance that a new brake actuator will fix it.
    rmacguy1949 posted above: "When this same thing happened it was the brake actuator, sorry"
    I assume you were referencing the sudden stop when backing up slowly. Is that correct?
    Did you have the same symptoms with all three warning lights coming on?

    Anyone else have to replace the actuator? If so, were your symptoms similar or same?

    Thanks for any help.
     
  11. ChapmanF

    ChapmanF Senior Member

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    Honestly, it would be worth getting access to Techstream and pulling the full (five-character) trouble codes. I'm not used to having trouble looking up the blink codes, but we did have trouble with yours, so Techstream would be the gold standard to find out what your brakes are trying to tell you (and might, in the process, also clear up what happened with the blink codes).

    Finding out what the brake system is trying to tell you can often save you a lot of effort compared to throwing parts at it. It may be trying to tell you something quite simple, like a learning procedure needs to be run. That would be easy to do and cost nothing.

    -Chap
     
  12. yaoaoatgyf

    yaoaoatgyf Member

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    Probably the best plan. I used to preach against throwing parts at cars many years ago when I was a professional tech. Although, by the mid 80's, there were "official" service docs for several brands, both foreign and domestic where the instruction on the flow chart would end with "replace the XXXX with a known good unit and see if that fixes the problem" Of course, that was pre OBDII days, and usually involved a complex (for the day) electronic part.

    Where do I go to subscribe to techstream?
     
  13. dolj

    dolj Senior Member

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