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post #1 of 8 (permalink) Old 04-18-2012, 01:37 PM Thread Starter
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Trouble Code Correlation?

A little back story, Im rebuilding a 2003 IS300 that was wrecked on the front end. The ECU box took a little damage as a result the electronic throttle was not working, hooked up the OBD2 scanner then watched my TPS sensor readout. It was reading 100% resistance signal (im guessing thats an open circuit?) Until I finger fucked the wiring of the ecu and then it went back to the correct level and electronic throttle came back.

Proceeded to clear codes, drove the car, car was fine. Get back and pull the codes and all of the throttle position codes are all back. My guess is the damaged wiring temporarily worked its way to an open circuit for a second.


My question is if one element of the system is taken out (say the TPS signal) would the engine throw all of these codes? I would figure it would just throw TPS P0123.


These are le codes.

P0123 - Throttle Position Sensor (G69): Signal too High
P2123 - Accelerator Position Sensor (G79): Signal too High
P2135 - Throttle Pedal Sensor 1 / 2 Correlation
P2138 - Accelerator Position Sensors (G79) / (G185): Implausible Correlation


Thanks for any help you guys may have.
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post #2 of 8 (permalink) Old 04-18-2012, 01:58 PM
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This car uses drive by wire up until about 70% throttle. If either the TPS or APPS signal was lost, the car would go into limp mode and the car would hesitate before ~70% throttle. Usually when I hear both sensors on the throttle body are throwing DTC's, then it most likely points to a issue in the wire loom(harness) or issue with the ECU. 100% resistance is equivalent to an open circuit. Each of these sensors have dual redundant signals, so if one of them is lost, the car goes into a default mode so it is still drivable. Since you are getting "signal too high or out of range" faults, then I would carefully inspect and ring the wire with a meter between the ECU pinouts and sensors themselves. So, no, I wouldn't think there's a correlation other than a wiring/ECU issue, in my opinion.

'02 IS300 MSM LSD
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post #3 of 8 (permalink) Old 04-18-2012, 02:35 PM Thread Starter
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Originally Posted by jasonm4444 View Post
This car uses drive by wire up until about 70% throttle. If either the TPS or APPS signal was lost, the car would go into limp mode and the car would hesitate before ~70% throttle. Usually when I hear both sensors on the throttle body are throwing DTC's, then it most likely points to a issue in the wire loom(harness) or issue with the ECU. 100% resistance is equivalent to an open circuit. Each of these sensors have dual redundant signals, so if one of them is lost, the car goes into a default mode so it is still drivable. Since you are getting "signal too high or out of range" faults, then I would carefully inspect and ring the wire with a meter between the ECU pinouts and sensors themselves. So, no, I wouldn't think there's a correlation other than a wiring/ECU issue, in my opinion.
But if they throw dual redundant signals... Wouldn't that mean there is a correlation? Basically one aspect of the TP system going out, causing the rest of the components throwing DTC's?
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post #4 of 8 (permalink) Old 04-18-2012, 03:50 PM
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Based on my diagnostic manual, Toyota labels these codes as such....
P0123-Throttle Position Sensor/Switch A Circuit High Input
P2123-Throttle/Pedal Position-Switch "D" Circuit high input
P2135-Throttle/Pedal position - A/B voltage Correlation
P2138-Accelerator Pedal Position (APP) Sensor 1/2(Throttle Position Sensor D/E) Incorrect Voltage Correlation

When you are getting all four of these codes, the DI section states there is an open or short, the sensors themselves, or the ECM. 3 of the 4 codes can relate the loss of E2, which is your sensor ground. So, if there was an issue with the TPS, it would not throw 2 DTC's related to the APPS. What I would do is get a helper and verify your wiring is not pinched or damaged by using a meter and jostling the engine wire loom to see of you lose your voltage reference or ground. Make sure each sensor is getting their 5 volts(blue/yellow stripe wire on both sensors) and are grounded via E2 which is the solid brown wire. I do not think you have two bad sensors. It's either wiring or ECU and it may take some time to ring the wiring. This is just my take based on what I've found.

'02 IS300 MSM LSD

Last edited by jasonm4; 04-18-2012 at 04:17 PM.
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post #5 of 8 (permalink) Old 04-20-2012, 07:55 AM Thread Starter
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Quote:
Originally Posted by jasonm4444 View Post
Based on my diagnostic manual, Toyota labels these codes as such....
P0123-Throttle Position Sensor/Switch A Circuit High Input
P2123-Throttle/Pedal Position-Switch "D" Circuit high input
P2135-Throttle/Pedal position - A/B voltage Correlation
P2138-Accelerator Pedal Position (APP) Sensor 1/2(Throttle Position Sensor D/E) Incorrect Voltage Correlation

When you are getting all four of these codes, the DI section states there is an open or short, the sensors themselves, or the ECM. 3 of the 4 codes can relate the loss of E2, which is your sensor ground. So, if there was an issue with the TPS, it would not throw 2 DTC's related to the APPS. What I would do is get a helper and verify your wiring is not pinched or damaged by using a meter and jostling the engine wire loom to see of you lose your voltage reference or ground. Make sure each sensor is getting their 5 volts(blue/yellow stripe wire on both sensors) and are grounded via E2 which is the solid brown wire. I do not think you have two bad sensors. It's either wiring or ECU and it may take some time to ring the wiring. This is just my take based on what I've found.
Thank you very much for the info, I know the issue lies in either my ECU or the wiring directly atop the ecu.

Again thank you sir.
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post #6 of 8 (permalink) Old 05-30-2012, 09:35 AM
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i got the engine code P2138 Accelerator Pedal Position (APP) Sensor 1/2(Throttle Position Sensor D/E) Incorrect Voltage Correlation

swapped out the tps for a new one.got the same code a day later.you think its a wiring problem or ECU?

98 VVTi SC300,Wet 100 Shot of NOS,Front LS400 BBK Calipers painted gold,Goodridge stainless steel braided brake lines,Blacken Emblems,Polished Intake,Tanabe Springs,8k Hid's 6k fogs,Tranny cooler w/fan,EXE Konvex Front 19x8.5,Rear 19x9.5.
14.1@96mph on NOS
NA-T-4" intake,Borg Warner 83-75,Stainless steel manifold,Tial 38mm WG,2 Blitz BOV,Aeromotive FPR,850cc,Twin in tank Walbro fuel pump,FFIM,AEM standalone,Aem Wideband,HKS Cam Gear,Blitz SBC i-D boost Controller(Need to Tune)
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post #7 of 8 (permalink) Old 05-30-2012, 09:51 AM
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Quote:
Originally Posted by 98$c300vvti View Post
i got the engine code P2138 Accelerator Pedal Position (APP) Sensor 1/2(Throttle Position Sensor D/E) Incorrect Voltage Correlation

swapped out the tps for a new one.got the same code a day later.you think its a wiring problem or ECU?
If you replaced the throttle position sensor, then you replaced the wrong sensor. P2138 is for the accelerator pedal position sensor as noted in the posts above. Also listed as 22060 in the diagram below. Also, after changing the throttle position sensor, you have to make sure you set it right because it's adjustable and very sensitive. You can't just slap it on there and tighten the two screws. See below, the APPS is the one attached to the throttle cable.
2002 IS300: OEM Engine & Fuel (FUEL INJECTION) Replacement Parts


'02 IS300 MSM LSD
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post #8 of 8 (permalink) Old 05-30-2012, 10:45 AM
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double post

98 VVTi SC300,Wet 100 Shot of NOS,Front LS400 BBK Calipers painted gold,Goodridge stainless steel braided brake lines,Blacken Emblems,Polished Intake,Tanabe Springs,8k Hid's 6k fogs,Tranny cooler w/fan,EXE Konvex Front 19x8.5,Rear 19x9.5.
14.1@96mph on NOS
NA-T-4" intake,Borg Warner 83-75,Stainless steel manifold,Tial 38mm WG,2 Blitz BOV,Aeromotive FPR,850cc,Twin in tank Walbro fuel pump,FFIM,AEM standalone,Aem Wideband,HKS Cam Gear,Blitz SBC i-D boost Controller(Need to Tune)

Last edited by 98$c300vvti; 05-30-2012 at 10:46 AM. Reason: double post
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