VSC and VSC Off Lights - Limp Mode
07-18-13, 04:33 PM
#391
OK, just spent an hour or so messing with this TB. First off, 2 months ago when I replaced the APPS the TB was clean as a whistle. Today I had to clean it around butterfly about an inch out. Not terrible but more than I expected to see. The ohm ranges are spec'ed out at 68 degrees. It was 95 here. Reading on APPS and TPS were 4.53 exactly for both. This should be expected because higher temperature leads to more resistance. The TCM was making a little bit of a friction noise and the ohms were low even considering the high temp. I think it is the TCM
07-18-13, 05:36 PM
#392
little research on resistance and temperature. With the wiring in the car, the ohms will increase linear with temp increase. If that is the case then, 68F/3200ohms = 96/x : X= 4,532 ohms at 96F
Can anyone confirm this?
Can anyone confirm this?
07-18-13, 05:38 PM
#393
Driver School Candidate
OK, just spent an hour or so messing with this TB. First off, 2 months ago when I replaced the APPS the TB was clean as a whistle. Today I had to clean it around butterfly about an inch out. Not terrible but more than I expected to see. The ohm ranges are spec'ed out at 68 degrees. It was 95 here. Reading on APPS and TPS were 4.53 exactly for both. This should be expected because higher temperature leads to more resistance. The TCM was making a little bit of a friction noise and the ohms were low even considering the high temp. I think it is the TCM
07-18-13, 05:44 PM
#394
Driver School Candidate
The best way to test TPS and APPS is to insert a metal pin into VTA1 or VTA2, then measure the output voltage as you rotate the APPS lever. If the APPS isn't working properly, then you will probably not see any change in the TPS.
07-22-13, 08:12 AM
#395
Driver School Candidate
Were you able to fix the limp mode problem after changing out the motor?
07-22-13, 10:36 AM
#396
Hi, what is a DMM? The motor came Fedex saturday but I was not home to sign for it. Now they don't deliver until Tuesday. FedEx sucks. Car is in the garage torn down.
07-22-13, 01:05 PM
#397
Lead Lap
Thread Starter
Im pretty interested in your repair of the APPS, did you repair some metal/carbon brushes inside of it, or what?
Nice to have a new spare now huh! :-) just in case.
Also, thanks for the info on voltages etc, my electronic repair manual is "somewhere" on my old computer drive, so I mostly just help people by memory, having exact values on the voltages and signals is nice. Thanks.
Nice to have a new spare now huh! :-) just in case.
Also, thanks for the info on voltages etc, my electronic repair manual is "somewhere" on my old computer drive, so I mostly just help people by memory, having exact values on the voltages and signals is nice. Thanks.
NP! Post back with your results. Toyota designed a flawed APPS. I bought a new APPS, but decided to disassemble my old APPS to see if I can decipher the failure mode. Took me three hours to make the corrective mod. So far so good. I still have a new sealed APPS (P/N 22060-46010) available for sale. Paid $275 with Toyota invoice. Local cash pickup in S Cal only.
I can help members who are local to S Cal trouble-shoot a defective APPS. The APPS will almost always test OK when cold. This part will usually fail when the engine is warm, resulting in erratic or no signal output at the VTA1 and VTA2 terminals. List price at Toyota is $400, but you can buy it online for about $300.
http://www.toyotapart.com/22060-46010.html
I can help members who are local to S Cal trouble-shoot a defective APPS. The APPS will almost always test OK when cold. This part will usually fail when the engine is warm, resulting in erratic or no signal output at the VTA1 and VTA2 terminals. List price at Toyota is $400, but you can buy it online for about $300.
http://www.toyotapart.com/22060-46010.html
07-22-13, 01:09 PM
#398
Lead Lap
Thread Starter
To Everyone:
One bit of advice I would suggest to ALL people working on engines with "newer" electronic controls is to get a Multi-Meter capable of reading Duty Cycle...almost all of the voltage signals going thru these cars, especially to controller motors and solenoids are Pulse-Width-Modulated signals, and reading voltages on them with normal voltage meters can be misleading.
Ive been working on my BMW lately and it saved me all sorts of time in diagnosing whether or not signals were being sent correctly
Just a suggestion.
One bit of advice I would suggest to ALL people working on engines with "newer" electronic controls is to get a Multi-Meter capable of reading Duty Cycle...almost all of the voltage signals going thru these cars, especially to controller motors and solenoids are Pulse-Width-Modulated signals, and reading voltages on them with normal voltage meters can be misleading.
Ive been working on my BMW lately and it saved me all sorts of time in diagnosing whether or not signals were being sent correctly
Just a suggestion.
07-22-13, 05:47 PM
#399
Driver School Candidate
Im pretty interested in your repair of the APPS, did you repair some metal/carbon brushes inside of it, or what?
Nice to have a new spare now huh! :-) just in case.
Also, thanks for the info on voltages etc, my electronic repair manual is "somewhere" on my old computer drive, so I mostly just help people by memory, having exact values on the voltages and signals is nice. Thanks.
Nice to have a new spare now huh! :-) just in case.
Also, thanks for the info on voltages etc, my electronic repair manual is "somewhere" on my old computer drive, so I mostly just help people by memory, having exact values on the voltages and signals is nice. Thanks.
The basic design of the APPS consists of two variable resistor pads that act over 90 degrees of rotation to supply VTA1 and VTA2 to the ECU.
The stepping signal at the control motor is also seen at the output side of the APPS (VTA1 and VTA2) in the form of noise spikes if the motor is connected to the ECU. I don't know if this is due to inadequate signal filter from the ECU or sign of a degrading ECU. The VTA1 and VTA2 outputs from the TPS are free from this anomaly.
07-22-13, 05:48 PM
#400
Driver School Candidate
07-22-13, 05:55 PM
#401
Driver School Candidate
To Everyone:
One bit of advice I would suggest to ALL people working on engines with "newer" electronic controls is to get a Multi-Meter capable of reading Duty Cycle...almost all of the voltage signals going thru these cars, especially to controller motors and solenoids are Pulse-Width-Modulated signals, and reading voltages on them with normal voltage meters can be misleading.
Ive been working on my BMW lately and it saved me all sorts of time in diagnosing whether or not signals were being sent correctly
Just a suggestion.
One bit of advice I would suggest to ALL people working on engines with "newer" electronic controls is to get a Multi-Meter capable of reading Duty Cycle...almost all of the voltage signals going thru these cars, especially to controller motors and solenoids are Pulse-Width-Modulated signals, and reading voltages on them with normal voltage meters can be misleading.
Ive been working on my BMW lately and it saved me all sorts of time in diagnosing whether or not signals were being sent correctly
Just a suggestion.
07-23-13, 12:31 PM
#402
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07-23-13, 07:04 PM
#403
Wow, fun night. Took entire throttle body off car and cleaned it like new. Installed new TCM and TPS. Had to adjust new TPS 3 times to get idling perfect. Car runs as good as it did when it was new. Drove it an hour with no issues. Daughter has it now and will keep me updated. Car threw codes and VSC lights came on upon initial startup. Cleared them and they never came back. Think I am good to go. Thanks for all the input.
07-24-13, 07:45 AM
#404
Driver School Candidate
Wow, fun night. Took entire throttle body off car and cleaned it like new. Installed new TCM and TPS. Had to adjust new TPS 3 times to get idling perfect. Car runs as good as it did when it was new. Drove it an hour with no issues. Daughter has it now and will keep me updated. Car threw codes and VSC lights came on upon initial startup. Cleared them and they never came back. Think I am good to go. Thanks for all the input.
The engine will ide high after you clean the throttle body. This is normal as the ECU will learn to dial in the correct idle speed after several drives. I would advise against adjusting the TPS to achieve the desired idle speed when warm.
07-24-13, 08:48 AM
#405
Lead Lap
Thread Starter
Nice work on that! I have solved similar problem with a ring sensor on GM 4WD trucks thats inside a $600+ "Encoder Motor" (the device that changes the Xfer case from 2WD to 4WD 4Lo etc)
GM dealers will only replace the entire encoder motor assembly, no ifs and or buts. But the ring sensor is a $64 part, takes 2 hours to replace.
Its a Hall-effect variable resistor, but the issue with it isnt a shim, its the tiny metal brushes they use wear out, and then scratch the resistor down to substrate. BAD BAD design.
I appreciate your technical info on this issue. I diagnosed this Limp-Mode problem using older fashioned methods and a std DMM before they had Duty Cycles, and I dont have a scope. I did that because Lexus would Only commit to replacing then entire Throttle Body if it wasnt the TPS sensor (which I already knew wasnt due to readings) so thus my journey started.
GM dealers will only replace the entire encoder motor assembly, no ifs and or buts. But the ring sensor is a $64 part, takes 2 hours to replace.
Its a Hall-effect variable resistor, but the issue with it isnt a shim, its the tiny metal brushes they use wear out, and then scratch the resistor down to substrate. BAD BAD design.
I appreciate your technical info on this issue. I diagnosed this Limp-Mode problem using older fashioned methods and a std DMM before they had Duty Cycles, and I dont have a scope. I did that because Lexus would Only commit to replacing then entire Throttle Body if it wasnt the TPS sensor (which I already knew wasnt due to readings) so thus my journey started.
This particular unit needs a 0.023" to 0.025" shim added between the white Teftlon back plate and the end of the rotating shaft. I use aluminum but shim can also be made out of steel. I glue the shim to the end of the rotating shaft.
The basic design of the APPS consists of two variable resistor pads that act over 90 degrees of rotation to supply VTA1 and VTA2 to the ECU.
The stepping signal at the control motor is also seen at the output side of the APPS (VTA1 and VTA2) in the form of noise spikes if the motor is connected to the ECU. I don't know if this is due to inadequate signal filter from the ECU or sign of a degrading ECU. The VTA1 and VTA2 outputs from the TPS are free from this anomaly.
The basic design of the APPS consists of two variable resistor pads that act over 90 degrees of rotation to supply VTA1 and VTA2 to the ECU.
The stepping signal at the control motor is also seen at the output side of the APPS (VTA1 and VTA2) in the form of noise spikes if the motor is connected to the ECU. I don't know if this is due to inadequate signal filter from the ECU or sign of a degrading ECU. The VTA1 and VTA2 outputs from the TPS are free from this anomaly.