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SAE vs. Toyota nomenclature

Discussion in 'Gen 3 Prius Main Forum' started by ez123re, Aug 31, 2024 at 10:02 PM.

  1. ez123re

    ez123re New Member

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    Seems like the SAE uses generic names in its OBD2 error codes, and manufacturers may use more customized names for the same things. I have a U0110 error code for both the Cruise Control and Hybrid Control, "Lost Connection With Drive Motor Control Module." I also have errors C1259 and C1310 for the brakes. Because brakes interact with the drive motor during regenerative braking, it makes sense that the drive motor control module could cause brake-related errors, so that module is my prime suspect.

    Next problem: to identify and locate the drive motor control module in the vehicle. I have yet to locate any relevant information online. I called the Toyota dealership, where the service department transferred me to the parts department. The parts guy says he has no listing for a part by that name. So what Toyota name does it go by?
     
  2. Tombukt2

    Tombukt2 Senior Member

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    In the generation 3 you're going to probably wind up down the rabbit hole changing both of the brake parts on the firewall like Toyota recommends. When the stuff starts failing there can be communication errors with other computers in the car just seemingly how it works I don't think you're looking to change computers and that sort of thing I think you're going to find your actuator and the other piece maybe having problems and then that causes the communication issues when they're not working properly or something along those lines Make sure you're using a very capable scanner so you can communicate with the whole can bus system I guess that is pretty important for this model vehicle.
     
  3. ChapmanF

    ChapmanF Senior Member

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    There aren't any brake parts wanting changed here. The only codes from the brake system, C1259 and C1310, are the codes it sets when it is notified about trouble codes set for the hybrid system. Those codes will go away when the hybrid system trouble is attended to.

    Yes, because that's a U0 code, it falls in the range of codes standardized by SAE, so the wording in its fortune cookie comes straight from SAE. If you had, say, a U1 code instead, that would be Toyota-defined and its fortune cookie would use Toyota wording (but also the same U1 code could mean something completely different in another car).

    [​IMG]

    So the difference between the SAE-standard and manufacturer-defined trouble codes turns out to be not very much in practice: if you're looking at a manufacturer code, you gotta look in the specific car model's repair manual to get the right explanation of what the code means. If you're looking at a 'standard' code, it has a 'standard' meaning, but you still gotta look in the specific repair manual to find out what part the manufacturer chose to use SAE's 'standard' name like Drive Motor Control Module "A" to actually mean. :)

    Toyota Service Information and Where To Find It | PriusChat

    It looks like someone will have to go online to look for U0110's full workup section, because there's a big PDF file floating around that somebody made by clicking Print-to-PDF a whole lot of times viewing the repair manual, but the U0110 section is among the ones that got missed.

    There are enough other mentions (cross references) of that code in the circulating PDF to make me think that Drive Motor Control Module "A" is probably the MG ECU, located inside the inverter assembly.

    But I wouldn't just charge in and replace that ECU. The U codes are communication codes; in this case, the power management control ECU under the dash (which handles both Hybrid Control and Cruise Control) is saying it can't communicate with the other ECU. The cause of the problem could be something in either ECU or in the wiring between them, so it pays to go through the troubleshooting steps and see what's really the root cause.

    Regrettably, those steps will be in the section that's missing from the easy-to-find PDF, so a visit to the repair manual online may be called for.