New DBW problem
#1
Staging Lane
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Hey guys, spent the last few hours searching the site without any luck.
05 5.3 out of a silverado. The dbw system was working fine yesterday. I have never had a problem out of it before. Started the car today, tried to give it a little gas and nothing happened. shut the engine off & left the key on & the throttle blade will not move with the pedal. I can still hear the blade move when i first turn the key on.
I checked my ground & power wires.
I checked continuity of ever wire between the TB, TAC, & pedal.
I checked the voltages coming from the pedal when pressing/depressing it.
Everything checks out, but I don't have an ODB2 port yet to check for codes.
I don't know anyone with a truck to test their parts & there are no newer DBW trucks at any junkyards in the area.
I had to step away from it for the night because I'm getting frustrated. Is there something I'm overlooking? Any advice?
05 5.3 out of a silverado. The dbw system was working fine yesterday. I have never had a problem out of it before. Started the car today, tried to give it a little gas and nothing happened. shut the engine off & left the key on & the throttle blade will not move with the pedal. I can still hear the blade move when i first turn the key on.
I checked my ground & power wires.
I checked continuity of ever wire between the TB, TAC, & pedal.
I checked the voltages coming from the pedal when pressing/depressing it.
Everything checks out, but I don't have an ODB2 port yet to check for codes.
I don't know anyone with a truck to test their parts & there are no newer DBW trucks at any junkyards in the area.
I had to step away from it for the night because I'm getting frustrated. Is there something I'm overlooking? Any advice?
#3
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Most GM DBW trucks have a problem with the throttle body itself. There is a GM special policy to rebuild the TAC module on the throttle body or replace the throttle body itself. It will throw a TP 1-2 correlation code for this, P21xx. There are also other instances where the pedal goes bad. That will throw an APP 1-2 correlation code. You can only replace the pedal for that concern. I'm a GM tech so I know this for a fact lol Once you are able to access codes, that will let you know what it is. Both concerns by the way can put the vehicle in "limp mode". Not as much with the throttle body, that will be a CEL, but the pedal throws a CEL and most of the time puts it in "limp mode".
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I had a similar problem.
When I read the code it was due to the voltage dropping at the computer when cranking the engine.
If the voltage drops below 8volts it throws a code and the throttle does nothing.
I turned it off and started it a few times and it was fine.
I'm in the process of upgrading the power feed to the computer as it's currently taking power off the starter motor and this is the end of the line so it has bad voltage drop.
When I read the code it was due to the voltage dropping at the computer when cranking the engine.
If the voltage drops below 8volts it throws a code and the throttle does nothing.
I turned it off and started it a few times and it was fine.
I'm in the process of upgrading the power feed to the computer as it's currently taking power off the starter motor and this is the end of the line so it has bad voltage drop.
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#9
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I'm going to the junkyard in the morning to get an ODB2 plug so I can wire it up & see if it's throwing any codes.
#10
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I wired up an obd2. The only code i got was P0118.
the pedal was working, opening the throttle body for a minute or two, then stopped working again. ran the scanner again, but still no other codes
the pedal was working, opening the throttle body for a minute or two, then stopped working again. ran the scanner again, but still no other codes
#11
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Bumping this up before I set this car on fire. PLEASE HELP
It started working on it's own for a couple months with no problems, then last week three blocks from the exhaust shop on the way to get it installed, it stopped again.
Here are the symptoms:
Everything will work for a few minutes, then the pedal will stop opening the throttle randomly.
Sometimes it will start working again a few minutes later. Sometimes it won't work for the rest of the day.
There are NO engine codes at all.
I have checked 5v references & grounds at the TB, TAC, & pedal.
I have tested the voltages coming from the pedal when pressing it.
I have tested the TP sensors in the throttle body and the continuity of them.
I have replaced the TAC module with the same results.
The TAC motor control - 1 & 2 going from the TAC to throttle body have a voltage of 1.6V & doesn't change regardless of pushing the pedal.
I don't know anything else to try...
It started working on it's own for a couple months with no problems, then last week three blocks from the exhaust shop on the way to get it installed, it stopped again.
Here are the symptoms:
Everything will work for a few minutes, then the pedal will stop opening the throttle randomly.
Sometimes it will start working again a few minutes later. Sometimes it won't work for the rest of the day.
There are NO engine codes at all.
I have checked 5v references & grounds at the TB, TAC, & pedal.
I have tested the voltages coming from the pedal when pressing it.
I have tested the TP sensors in the throttle body and the continuity of them.
I have replaced the TAC module with the same results.
The TAC motor control - 1 & 2 going from the TAC to throttle body have a voltage of 1.6V & doesn't change regardless of pushing the pedal.
I don't know anything else to try...
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I had this issue too. Someone on here recommended to epoxy a penny under the pedal stop. Reason being that when the throttle closes too quickly the voltage drops too fast for the computer to keep up and sees this as a problem and shuts down the pedal. I did the penny trick and haven't had a problem since.
#13
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I had this issue too. Someone on here recommended to epoxy a penny under the pedal stop. Reason being that when the throttle closes too quickly the voltage drops too fast for the computer to keep up and sees this as a problem and shuts down the pedal. I did the penny trick and haven't had a problem since.
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Supposedly not. After a few key on cycles the computer relearns the position. The theory behind this is that the penny keeps the voltage higher when the throttle snaps shut. I am using an Avalanche pedal that was a factory adjustable setup that I had to cut down for my Mustang and only has a pedal throw of about 3/4 of an inch.
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Tried the penny. No luck.
I also bought another throttle body with no change.
No error codes. I'm tired of wasting money on something that worked fine a few weeks ago. So where do I go from here??
I've tried resetting the computer & relearning every possible combination of the throttle bodies & TAC's I've bought and nothing works. The only thing I haven't replaced is APP sensor. But with no check engine codes, i'm not going to waste money on that unless I know for sure it needs to be replaced.
I also bought another throttle body with no change.
No error codes. I'm tired of wasting money on something that worked fine a few weeks ago. So where do I go from here??
I've tried resetting the computer & relearning every possible combination of the throttle bodies & TAC's I've bought and nothing works. The only thing I haven't replaced is APP sensor. But with no check engine codes, i'm not going to waste money on that unless I know for sure it needs to be replaced.
Last edited by Stev0n; 11-22-2013 at 07:32 PM.
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You should check the plug at the throttle body, I've heard one of the terminals there can work its way loose due to corrosion. Try gently tugging on each wire on that plug to see if one is loose.
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You should check the plug at the throttle body, I've heard one of the terminals there can work its way loose due to corrosion. Try gently tugging on each wire on that plug to see if one is loose. Video Link: http://m.youtube.com/watch?v=U2DjMcM_Quk
Does anyone have any other advice outside of buying a new app sensor
#20
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I checked all the wires on the throttle body plug. None of then are loose.
EDIT
Here's an interesting twist.
If I turn the key ON, the pedal won't work.
But if I take the negative battery cable off then put it back on, the pedal will start working for a few seconds then stop again.
If I take the cable off, then put it right back on, it will work again for a few seconds.
wiggling the battery cable or trying to tighten it seem to have no effect once it stops working. Taking it off and putting it back on is the only way make the pedal/TB start working again.
EDIT
Here's an interesting twist.
If I turn the key ON, the pedal won't work.
But if I take the negative battery cable off then put it back on, the pedal will start working for a few seconds then stop again.
If I take the cable off, then put it right back on, it will work again for a few seconds.
wiggling the battery cable or trying to tighten it seem to have no effect once it stops working. Taking it off and putting it back on is the only way make the pedal/TB start working again.
Last edited by Stev0n; 11-23-2013 at 05:17 PM.