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Shift Control Actuator, Temp. Over-Ride.

Discussion in 'Gen 2 Prius Technical Discussion' started by SteveWlf, Feb 1, 2013.

  1. SteveWlf

    SteveWlf Old-on-Hold

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    I have two Gen2 Prius in my shop for repairs and this frequently requires they be transported or moved with out aux battery or HV battery. Or might have inactive ECU system, lack of Smart Key, etc.. This means the Park Pawl will remain engaged and so far the only way I have been able to move these cars is restore the batteries or remove one of the axles.
    Since I expect this problem will recur again since I find these cars a new challenge for my "Auto Repair interests".
    The overall is seen in The System Diagram and System Operstion has a good discription of the Park Pawl motor
    Here are my thoughts on releasing the Parking Pawl. The motor operated pawl is controled by the Transmission Control ECU of the Shift Control Actuator Assembly and a Relay on the Eng. Rm. R/B and J/B.
    Of course, the ECUs are not going to be of any help without the batteries or Smart Keys. The Pawl Control Relay could be jumpered but the Tranny Control ECU still controls the ground leg of the stepping motor in the Shift Control Actuator Assembly.
    Access to mechanically release the Pawl would be difficult and I don't want to try over ride the ECU circuits for lack knowledge of the signal levels, etc.. If there is no power to the Tranny ECU then switching the Gnd signal to the stepping motor would be the biggest and most risky problem.
    I'm thinking, unplug the connector that goes directly into the Actuator Assembly which will also completely isolate the sensor signals from the Tranny ECU.
    Now, I may be getting in way over my head here and that is why I pose this idea here. I'm a retired Mfg Eng. (not an EE) but have some understanding of stepping motors and with a little help, might be able to figure this out by trial and (hopefully no harmful errors).
    I do have the advantage of having a good spare transaxle in my shop. I have observed in a YouTube video that the Shift Actuator Assembly and Shift Pawl can be easily opened/exposed for examination.
    I'm thinking that I might develop a 12 volt/dc switch w/indicator lites
    on a pendent assembly that I can plugin when I need to move a car. The plug is accessable from the left rear side of the tranny.
    I would really appreciate some thoughts, comments or suggestions.
    Thanks
    Steve
     
  2. nh7o

    nh7o Off grid since 1980

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    You will find the project a little more challenging than a stepper motor. The parking pawl motor is a three phase type of motor which drives a gear. This requires an AC source of the proper frequency for the motor. We don't know the voltage or frequency of this motor, but I might guess it is somewhere around 12V P-P (i.e. not driven from the high voltage system) @400Hz or so. If that is not right it might still be suitable to make the motor spin. Some experimentation is required. You might find some small old Air Force surplus generator set that can put out 3 phase at high frequency.

    I'm sure some of the other experts will weigh in on the voltage/ freq. Once you have the power source, you will be able to spin the motor, but also would need to be careful not to run it against the stops too forcefully.
     
  3. dogfriend

    dogfriend Human - Animal Hybrid

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    If you know you are going to need to move the car without the battery, the easiest way around this problem might be to prevent the parking pawl from engaging in the first place while the car is still powered up. I think you can do this by removing the PCON relay (or possibly the PCON fuse) while NOT in P, then powering down. I haven't tried this so no guarantee and you assume all risk. You will probably set some codes too.
     
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  4. SteveWlf

    SteveWlf Old-on-Hold

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    Yes, I see your point and recognize the complexity of the 3 phase motor. If we are to trust the "over simplification" the manual diagram, I would assume the Pos would be 12volt from the Aux battery and would guess the Neg from MWA, MVA and MUA of the Transmission Control ECU. Again, guessing, the frequency would be determined by the cycle rate between those three phases. So, for simplicity sake, I have a, say rotory switch with every third contact representing the neg of phase W,V,A leg. then I could spin the switch to step the motor. Noted, the Cycloid reduction mechanism rotates only a single tooth for each motor shaft revolution (10:1). Admitidly there will be a lot of torque on the pawl shaft and establishing the limit might be accomplished through the sense signal outputs from the Shift Control Actuator Assy.
    Yes, I tend to over simplify things, lacking the knowledge of an EE, but veiwing this in the simplest of mechanical terms, I'm hoping to Cobble something to gether that will safely move and disengage that pawl. Again for a mechanical approach I know I could remove the motor or the pawl latch cover and manually lift the pawl but either of these choices are complicated with the transmition being in the car, where the shift control assy connector is much easier to remove and would prevent the system ECUs from detecting or interfering with the pawl over-ride.

    I also agree with DogFriend and recognize that as a very easy process, if the smart key and other systems are operational. But in 50% of the cars (in my shop, 1 of 2) I can't get to the Ready stage and get it out of park and expect that might be typical in the future. Example, a Prius breaks down on the road or some other location and needs to be towed to shop, can't roll it onto a trailer or dolly, can't even push it into a parking space. Only recourse is an expensive tow truck with wheel lift, just to move it a few feet or a few miles. Or as I have done, removed one of the axles which means draining half the tranny oil or disassembling the inter tripod axle joint.

    (didn't I once say "I look forward to the new chanlenges of the Prius", or word to that effect. I also enjoy the topics, comments and fellowship of this forum.)

    Steve
     
  5. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    On some of the classics I work on we put them on wheel rollers. So every wheel has a little roller only a couple of inches high and then essentially the car is in casters.

    [​IMG]

    With a traditional car, I don't want to be starting it just to move a couple feet and so on. Not good for the battery, engine, starter, anything really. But you can apply these by just jacking up each wheel individually, rolling this under, then lowering the jack. Now the entire thing can be pushed around.

    As to disengaging the parking pawl, if you cannot get the car to READY, it will be a pain. Doable, but a pain. Does anyone know if the signal is chopped low side or high side? I can put my scope on it and press the button a few times to see what pops up. It is an area of the car I have never investigated. I generally stay in the cabin decoding CAN messages.
     
  6. Britprius

    Britprius Senior Member

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    A solution could be engineered by using the output directly from another parking pawl motor rotated by hand, this should produce the correct waveform to turn the the one in the vehicle.

    It should even be possible to use the output of a spare MG1 or MG2.

    This if I remember correctly is demonstrated in the transmission tear down video where MG1 and MG2 are connected together and when one is turned by hand the other turns.

    John (Britprius)
     
  7. SteveWlf

    SteveWlf Old-on-Hold

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    I have a set of these wheel dollys but they are not usable on gravel, rough surfaces or of any assistance in getting a Prius on a roll-back truck, trailer or dolly. Since my movement at the shop usually involves moving it out of the shop bay to allow me to move another in, I would end up on gravel outside the shop.

    I don't have the ability or the skills to observe the signal levels, etc.. My electrical education/skill developement ended in highschool shop/science class. Plus a little in learning the use of stepping motors and solinoids, etc.. in the manufacturing process. Know the difference between AC and DC and manage to wire my own shop 3 phase equipment without killing myself or any machines. Made it though nearly 70 yrs of automotive DIY repairs without much outside assistance. Again the, the Prius is a new Challenge! to keep the mind alert!

    Steve
     
  8. SteveWlf

    SteveWlf Old-on-Hold

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    Johon, I agree that the phases of the shift control motor should follow that of another Pawl Motor, but definate;ly not the MG1 or MG2 since they are HV AC 3 phase while the Pawl motor is 12 volt DC.
    Even though I do have the spare transmission available in the shop for this R&D of a Parking Pawl Dongle, I can't commit the spare pawl motor to this project beyond the R&D. Worth too much $$.

    Thanks to all who are responding. All adeas are worth considering and of value in this process, with no disrespect intended in my above comments.

    Steve
     
  9. Britprius

    Britprius Senior Member

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    Steve the parking pawl motor is not DC it is 3phase AC effectivelygenerated by the parking pawl ECU.

    The voltage from MG1/2 is speed dependent turning it by hand will not produce 500 volts (the reason the Prius drops out of regen below 7mph not enough voltage to be above that of the battery).

    A parking pawl motor if rotated will act as a three phase generator all that is required is for those three phases are connected as with any other 3phase motor. The center "star point" is not required and if the phases are not in the correct order all that will happen is the direction of rotation will be reversed.

    John (Britprius)
     
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  10. nh7o

    nh7o Off grid since 1980

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    How about making a jumper cable that connects the shift control ECU from the working car to the parking pawl motor on the car that you want to move? The working car doesn't need to know that the motor itself is on a different chassis.
     
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  11. SteveWlf

    SteveWlf Old-on-Hold

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    I do tend to agree that the Parking Pawl ECU would control the negative of each phase, in sequence. However, with all due respect (and maybe some ignorence), I don't see how this could shift the polarity of individual phase windings since the positive is being constantly or common center connection is supplied by the Aux battery. In other works we would never see the traditional 3 phase or even a single phase wave form so I don't see how it could be called AC.

    If someone has a scope and could access the leads to the shift pawl connection, it would be interesting to find out what the wave form (or frequency) looks like.

    I have watch a YouTube video of the Prius tanny tear down and the demonstate the MG1/MG2 reaction when interconnected to each other and rotated by hand. You can see the driven MG shift from pole to pole while the driver is rated slowly. Not sure of the difference between syncro and stepping motor reaction but the MG example seems like "Syncro". Again I could be wrong and often am.

    Steve
     
  12. SteveWlf

    SteveWlf Old-on-Hold

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    I rolled out my spare Prius Gen2 transaxle and pulled a couple cover plates. The Toyota manual lacks details of the internal workings and I wasn't able to tell much more through these opening. I actually got more info from the YouTube video I had watched last week. What I did note was that there is only about 15 deg. of rotation of the internal pawl shaft between the two detents. Without removing the Shift Assembly motor, I removed the shift detent leaf spring and detent roller. The quadrant with the detent notched and rod link going inside the gear case to the Pawl. I could not view the Pawl from the area I had opened. I tried to move these components with my hand but there was too much resistance to shift the pawl. This was probably because of the cyloid gear reducer (1:10 rev.).
    So, a mechanical solution might be to remove the motor and stick a special splined shaft and lever into the drive coupling of the cycloid gear reducer and crank it until the pawl is with drawn.. Sounds do-able on the in the shop but there isn't enough room to do this from under the car. (just barely enough room to pull the connector plug).

    Steve (still learning @ 75)
     
  13. SteveWlf

    SteveWlf Old-on-Hold

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    Still looking at this problem of disengaging the Park Pawl. However, there is one question that I still should consider.
    At what step or phase of the Smart Key/emobilizor process can the park release allowed. I realize it ain't going to happen if the the key FOB insn't inserted or proximity in the case of the Smart Key.

    Right now of the two Gen2s in my shop, neither is operational electrically, only one having the key FOB. So if the key fob is available but the electical system has problems, either in the ECUs or battery faults Red Tiangle, no READY, etc..?? If the car is in Park already, at what "State" until READY will the Park button be effective??


    To put it another way. If a Gen2 goes into an InOp mode due to problems, I have noted that you can't remove the FOB until it is returned to Park. Haven't been able to check this, but can the Park be released once the FOB is inserted, inspit of other Error problems??

    If not, just how would a dealer be able to move a dead Gen2 or Gen3 into or out of the service bay??

    Steve
     
  14. nh7o

    nh7o Off grid since 1980

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    I don't know for certain, but it would make a lot of sense if the Techstream software would allow for the parking pawl motor to be run, via a specific command, even if the car was not in ready mode. (If you have a laptop, look for "mini vci" on eBay.) That functionality, if it exists, would be well hidden from user land.

    Other DTC's can exist but still allow the car to go into ready mode. It would depend on which specific ones are set. No way to know without looking them up in the service manual.
     
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  15. Britprius

    Britprius Senior Member

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    Steve the pawl motor is wired in a star configuration, and as such will act as a three phase motor if a supply is applied.

    If you put a DC supply across any two of the outer coil connections it will be seen that the current will flow through two of the coils. What is not immediately apparent is that the coils are connected with opposite polarity making one winding attract and the other winding repel the rotor magnet stepping the motor round one pole position.

    As with all motors of this type the speed of the motor is governed by two things. The frequency of the AC supply and the number of motor poles "the more poles the slower the motor".

    The shape of the waveform to make the motor run in this instance will make little or no difference be it square or sine waves, it will affect how efficient it is but for your purpose this does not matter.

    AC stands for alternating current but it does not have to be in a sine wave. Before I retired my work was 60% positional motor control systems mostly for industrial robots and automated production lines.

    John (Britprius)
     
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  16. SteveWlf

    SteveWlf Old-on-Hold

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    Agree! At last! I'm more mechanical that electrical and my knowledge (very) limited is to Stepping motor, solinoids and relays in manufacturing processes. And what you porpose here goes along with my thoughts to set up a commutator/rotory switch that would allow me to rotate from pole to pole in sequence to cause the pawl lock motor to follow one phase coil at a time.
    The cyloid torque muliplyer has a 10:1 ratio and the quadrant/lever arm only has to shift about 12-15 deg. to move from pawl locked to pawl fully disengaged (into the locked out detent). So the motor would have to rotate between 25 to 30 revolutions. Since we can't observe the location of the pawl linkage and the torque multiplyer having great advantage, it becomes necassary to monitor the open/latched postion. Therefore I must look into the signals of the position sensors Shift Control Actuator. In the electrical diagrams I see there are 5 connection that seem to be related to this sensor function.
    Looking at the transmission ECU connector T4 (page 05-1150), we see pin16 E2 is Body GND, pin17 is VC-E2 Power Source (rotary angle sensor) 4.5 to 5.5 Vdc, pin4, pin5, pin6 are each rotary angle signals. From this and the shop spare tranny actuator, I hope to figure out what type of sensor device this is.

    I truly think there is a fairly simple way to accomplish this but I must approach it carefully since I don't want to damage the spare Actuator I have. I don't have any test equipment beyond a Fluke digital meter and a simple logic probe. Since we now know that the sensor it basically 5vdc I suppose I can use a 5vdc power source to power the sensor circuit and then use the logic probe to see what activity there is static and then manually rotate the motor shaft with it out of the tranny. From that I think I could tell what the signal level combination would be in each extreme limit conditions. Lock or Unlocked. Then, maybe back to my old Bread Board and do some TTL logic circuits (seems like the '70s again).

    Who know, maybe I will eventually develope a Dongle for this purpose.
    BTW. I have found that the Transmission ECU connector is more easily eccessable from under the glove box than trying reaching the Actuator on the tranny.

    Steve
     
  17. babybird

    babybird Member

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    The fob won't lock into the slot if you only insert it about 2/3 into the slot but it will still operate the ignition.
     
  18. Alexey Kryuchkov

    Alexey Kryuchkov New Member

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    Have the same problem. But don't listen to people who tries to help you based on your description and specially who is talking about MG1 and MG2 and 500V as they all just wanna type something :)

    Have you guys seen the connector for 500V???? Pawl actuator has powerfull 12V connector 100%.
    It is operated even if HV battery is disconnected - meaning 12V.
    Also it has 4 wires for coils and 3 wires for sensors. It means it's operated not by AC and actually MG1 and 2 not really AC motorsalso, but by DC impulses ( like MG1 and 2). Also the rotation is carefully controlled via 3 sensors.

    So the task is not really difficult, time consuming though.

    What we need to do - is to make a simple controller to operate this motor. :)
    Don't waste your time on sensors. They do not show extreme positions at all. they just monitor the position of the rotor to properly "rotate the field" and also should count turns.
     
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