troubleshooting DBW - limp mode & TPS/APP code
Thread Starter
Teching In
Joined: Aug 2020
Posts: 7
Likes: 0
troubleshooting DBW - limp mode & TPS/APP code Hi all-- first off, thanks for taking the time to lend a helping hand to others!
I've got an LS swap in my truck (defender 90) for the past 3 years, and it hasn't given me too much trouble. It was a crate engine, I believe built off the specs for the 2011 LS3 6.2. Over the past two years I kept running into an issue where I'd be driving and it would drop to limp mode where the throttle would become unresponsive. After pulling over, checking the connector at the accelerator pedal, and starting up again things would be back to normal. It probably happened once or twice every 6 months or so.
Then about a week ago the same thing happened, and I couldn't for the life of me get the throttle to respond. Had it hauled to my place, read the code and it came back P2138 "Throttle/Pedal Position Sensor/Switch D / E Voltage correlation. I tried it the next day, and the throttle responded again but after about 3 blocks it stopped responding again. Checked the connections, started it again and after another 2 blocks it went into limp mode again.
Since then, I've been trying to troubleshoot whether it is the position sensor on the pedal, on the throttle body, or something else (maybe a short somewhere)? When I use an OBD2 reader (bluedriver) and check all the throttle-related sensor outputs that I can find, they seem to register the full range of pedal positions while the engine is off. I couldn't find a pedal angle where the signal dropped out. My big question is if it's possible to pinpoint if the problem is the pedal or throttle using either the OBD2 reader or maybe a voltmeter? Or do I need to start switching out one part at a time to see if that fixes it?
Thanks!
I've got an LS swap in my truck (defender 90) for the past 3 years, and it hasn't given me too much trouble. It was a crate engine, I believe built off the specs for the 2011 LS3 6.2. Over the past two years I kept running into an issue where I'd be driving and it would drop to limp mode where the throttle would become unresponsive. After pulling over, checking the connector at the accelerator pedal, and starting up again things would be back to normal. It probably happened once or twice every 6 months or so.
Then about a week ago the same thing happened, and I couldn't for the life of me get the throttle to respond. Had it hauled to my place, read the code and it came back P2138 "Throttle/Pedal Position Sensor/Switch D / E Voltage correlation. I tried it the next day, and the throttle responded again but after about 3 blocks it stopped responding again. Checked the connections, started it again and after another 2 blocks it went into limp mode again.
Since then, I've been trying to troubleshoot whether it is the position sensor on the pedal, on the throttle body, or something else (maybe a short somewhere)? When I use an OBD2 reader (bluedriver) and check all the throttle-related sensor outputs that I can find, they seem to register the full range of pedal positions while the engine is off. I couldn't find a pedal angle where the signal dropped out. My big question is if it's possible to pinpoint if the problem is the pedal or throttle using either the OBD2 reader or maybe a voltmeter? Or do I need to start switching out one part at a time to see if that fixes it?
Thanks!
Launching!
Joined: Jan 2004
Posts: 199
Likes: 20
Had a similar issue with my dead stock daily driver silverado. The wiring harness to the throttle body was not supported well at the connector and the wires fatigued/ broke at the connector, not fully, but enough to randomly drop into limp mode. I spliced in a new harness / connector and zip tied the harness to prevent it from flopping.
i dont recall the test procedure, its been a few years, I looked it up from the error code, but you can isolate if its at the pedal or throttle body and test with a multimeter.
i dont recall the test procedure, its been a few years, I looked it up from the error code, but you can isolate if its at the pedal or throttle body and test with a multimeter.
Registered User
Joined: Aug 2023
Posts: 1
Likes: 0
Hi all-- first off, thanks for taking the time to lend a helping hand to others!
I've got an LS swap in my truck (defender 90) for the past 3 years, and it hasn't given me too much trouble. It was a crate engine, I believe built off the specs for the 2011 LS3 6.2. Over the past two years I kept running into an issue where I'd be driving and it would drop to limp mode where the throttle would become unresponsive. After pulling over, checking the connector at the accelerator pedal, and starting up again things would be back to normal. It probably happened once or twice every 6 months or so.
Then about a week ago the same thing happened, and I couldn't for the life of me get the throttle to respond. Had it hauled to my place, read the code and it came back P2138 "Throttle/Pedal Position Sensor/Switch D / E Voltage correlation. I tried it the next day, and the throttle responded again but after about 3 blocks it stopped responding again. Checked the connections, started it again and after another 2 blocks it went into limp mode again.
Since then, I've been trying to troubleshoot whether it is the position sensor on the pedal, on the throttle body, or something else (maybe a short somewhere)? When I use an OBD2 reader (bluedriver) and check all the throttle-related sensor outputs that I can find, they seem to register the full range of pedal positions while the engine is off. I couldn't find a pedal angle where the signal dropped out. My big question is if it's possible to pinpoint if the problem is the pedal or throttle using either the OBD2 reader or maybe a voltmeter? Or do I need to start switching out one part at a time to see if that fixes it?
Thanks!
I've got an LS swap in my truck (defender 90) for the past 3 years, and it hasn't given me too much trouble. It was a crate engine, I believe built off the specs for the 2011 LS3 6.2. Over the past two years I kept running into an issue where I'd be driving and it would drop to limp mode where the throttle would become unresponsive. After pulling over, checking the connector at the accelerator pedal, and starting up again things would be back to normal. It probably happened once or twice every 6 months or so.
Then about a week ago the same thing happened, and I couldn't for the life of me get the throttle to respond. Had it hauled to my place, read the code and it came back P2138 "Throttle/Pedal Position Sensor/Switch D / E Voltage correlation. I tried it the next day, and the throttle responded again but after about 3 blocks it stopped responding again. Checked the connections, started it again and after another 2 blocks it went into limp mode again.
Since then, I've been trying to troubleshoot whether it is the position sensor on the pedal, on the throttle body, or something else (maybe a short somewhere)? When I use an OBD2 reader (bluedriver) and check all the throttle-related sensor outputs that I can find, they seem to register the full range of pedal positions while the engine is off. I couldn't find a pedal angle where the signal dropped out. My big question is if it's possible to pinpoint if the problem is the pedal or throttle using either the OBD2 reader or maybe a voltmeter? Or do I need to start switching out one part at a time to see if that fixes it?
Thanks!
Just to add to that the pedal still works at the moment.
Thanks
Pete
TECH Senior Member
Joined: Jun 2016
Posts: 22,291
Likes: 3,616
From: Central Cal.
Did you ever manage to resolve this? I have exactly the same issue on exactly the same car with the same engine swap!! I have ruled out most things including pedal, Throttle body etc. Entire loom was new from speartech. It's super intermittent when it loses throttle but the code is now there all the time.
Just to add to that the pedal still works at the moment.
Thanks
Pete
Just to add to that the pedal still works at the moment.
Thanks
Pete
