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Posted: 12/12/2013 1:47:06 PM EST
I have a FJ40 with a 5.3l Vortec that was transplanted out of a Silverado 1500 mated to a 4l60e transmission.

Tonight while driving around town, I lost the ability to throttle my engine. The car was traveling approximately 30 mph at a relatively low RPM. All of the sudden, my RPMs dropped to an idle, and my gas pedal was not controlling my engine. My car has the stock silverado 1500 drive-by-wire gas pedal, so there is not a cable controlling a throttle anywhere; it is an electrical sensor in the pedal that sends the signal to the throttle via a wire.

I pulled over and turned off the engine with the ignition. I was able to restart the engine like normal, but the pedal still did not work--only an idle from the engine.

My car is equipped with a battery-cut-off switch. I then turned the engine off with the ignition, and cut electric power with the cut-off switch. I turned the power back on and restarted the engine. This fixed my problem. Gas pedal worked like normal. I gave it some revs and it was working just fine.

I put it into drive and after a few seconds, I lose power, get an idle, and have no control of the throttle.

I go through the same process again, revving it once the problem appears to be solved.

Every few seconds of driving, I have to go through the whole process again. It only seems to lose power when I am moving. The RPM speed does not seem to make it better or worse.



Any idea what could be wrong? It sounds kinda like a short to me (as it only occurs when I am moving (maybe a lose wire??)). I sure hope I am wrong though! Is there some sort of sensor that might be malfunctioning? As far as I can tell, it is not throwing any type of codes either.

Help me.
Link Posted: 12/12/2013 1:49:57 PM EST
[Last Edit: 12/12/2013 1:56:00 PM EST by HSDM]
Throttle-by-wire sensor is going out. How hard is that to replace? Can you jerry rig an actual throttle cable until you figure it out?

Edit: Digging around shows that the throtle actuator control can go bad and to fix it you need to replace the whole throttle body and actuator because they are one piece. There is also a throttle position sensor that can go bad too.
Link Posted: 12/12/2013 1:54:16 PM EST
limp mode on the tranny?
Link Posted: 12/12/2013 1:56:57 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By J75player:
limp mode on the tranny?
View Quote


What does that mean? I am not familiar with that term.
Link Posted: 12/12/2013 1:57:49 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By HSDM:
Throttle-by-wire sensor is going out. How hard is that to replace? Can you jerry rig an actual throttle cable until you figure it out?

Edit: Digging around shows that the throtle actuator control can go bad and to fix it you need to replace the whole throttle body and actuator because they are one piece. There is also a throttle position sensor that can go bad too.
View Quote


Oh fun! $$$ I hope thats not it either.
Link Posted: 12/12/2013 1:58:46 PM EST
Fuel pump?
Link Posted: 12/12/2013 2:08:54 PM EST
Are you getting a SES light? if so please post OBD2 codes.
Link Posted: 12/12/2013 2:11:26 PM EST
the GM trucks have problems with the wires going into your electronic drive by wire module and the throttle body.
there is a pull test you can perform and that may find your problem and lead you in a direction to fix. (ive had the same problem, but i got a reduced engine power warning)
Link Posted: 12/12/2013 2:12:30 PM EST
[Last Edit: 12/12/2013 2:13:44 PM EST by Diesel24]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By squirrelslayer1:


What does that mean? I am not familiar with that term.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By squirrelslayer1:
Originally Posted By J75player:
limp mode on the tranny?


What does that mean? I am not familiar with that term.

You can think of it as a "protect" mode on your transmission. I have an allison, so I'm not too familiar with yours but I would imagine it wouldn't operate too much differently.

Basically what happens is the tranny can't handle the load you put on it, so it goes into limp mode, not allowing you to go over X amount of RPMs. Clearing out the code the tranny throws will take it out of limp mode, however you should get to the cause of why it went into limp mode. This of course only applies if this is your problem.

ETA: Reading your post in more detail, it isn't a limped tranny. Never the less, now you know what the term means.
Link Posted: 12/12/2013 2:13:24 PM EST
Depending on your year... Rockauto has the throttle body for about 130... Not too bad if that's the problem.

Are you able to hook a diagnostic computer up to your drivetrain? I've gotta imagine that threw a DTC code.
Link Posted: 12/12/2013 2:18:43 PM EST
would check wiring maybe a wire has rubbed or partially melted together due to exhaust.common problem is throttle body going bad.
Link Posted: 12/12/2013 2:20:42 PM EST
Pedal position sensor would be my first guess.

Pulled from Rockauto:

DORMAN Part # 699101 {#15120405, 15264643, 89059124} Type: Sensor Only
$34.99

Link Posted: 12/12/2013 2:22:21 PM EST
hook up a scan tool and watch the throttle input. Also check for codes there should be a history code from your issue.


I personally suspect the throttle pedal but I wouldn't NOT throw parts at the issue.
Link Posted: 12/12/2013 2:26:12 PM EST
exhaust bearings are going out
Link Posted: 12/12/2013 2:29:43 PM EST
Being it is a swapped car, I'd guess its a wiring issue. Follow the harness off of the gas pedal and look for chafes. Then look around the throttle body and the harness. Like another guy said, if its a gm harness they break wires on occasion a few inches away from the tb. Pull codes before anything thouh.
Link Posted: 12/12/2013 2:44:19 PM EST
Link Posted: 12/12/2013 3:41:57 PM EST
1.physical wiring damage
2.pedal is fried
3.throttle body actuator is toast/TPS sending unit is toast
4.PCM

Check here and keep me updated. LS engines are easy to diagnose.

Link Posted: 12/12/2013 3:47:29 PM EST
There is a rebuild kit you can buy from the dealership for the throttle body.

That being said

Any codes? There are known pinfit issues with the wiring harness to thottlebody.


Did you transplant the whole harness or buy a aftermarket one?
Link Posted: 12/12/2013 4:14:32 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By jeep450:
There is a rebuild kit you can buy from the dealership for the throttle body.

That being said

Any codes? There are known pinfit issues with the wiring harness to thottlebody.


Did you transplant the whole harness or buy a aftermarket one?
View Quote


It's got a Painless harness. I'll put the scanner on it and watch for codes.
Link Posted: 12/12/2013 4:28:58 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By joshiedoom:
1.physical wiring damage
2.pedal is fried
3.throttle body actuator is toast/TPS sending unit is toast
4.PCM

Check here and keep me updated. LS engines are easy to diagnose.

View Quote



This
Link Posted: 12/12/2013 4:33:23 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By HSDM:
Throttle-by-wire sensor is going out. How hard is that to replace? Can you jerry rig an actual throttle cable until you figure it out?

Edit: Digging around shows that the throtle actuator control can go bad and to fix it you need to replace the whole throttle body and actuator because they are one piece. There is also a throttle position sensor that can go bad too.
View Quote

+1, throttle position sensor, same thing happened on my work vehicle a 2011 Chevy Tahoe.
Link Posted: 12/12/2013 4:52:51 PM EST
throttle body is bad, some years you can replace just the sensor. others you need the whole body
Link Posted: 12/12/2013 5:09:44 PM EST
Link Posted: 12/12/2013 5:36:45 PM EST
Throttle position sensor or pedal position sensor. It should store a DTC.
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