Stev0n

iTrader: (7)

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?

62n62

iTrader: (17)

any codes

TimmyZ28

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".

SOHCNightmare

If you don't have an OBD2 port I imagine you're going to have to find someone with a bench cable to read your codes. Why don't you have an OBD port?

Stev0n

iTrader: (7)

I just got the car running this week. still finishing up the wiring

zuffen

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.

garys 68

iTrader: (1)

I've noticed after winter storage my pedal acts up. Guessing due to corrosion in the pedal position sensor. Disconnect the battery, pump the pedal a few times, start it and it's fine all season.

slotruk90

In my swap I had trouble with the tac module ground. I grounded it, and no problem since.

Stev0n

iTrader: (7)

Hmm.. this might be something i should try. physically grounding the tac box as well as the factory ground wires coming out of it.


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.

Stev0n

iTrader: (7)

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

Stev0n

iTrader: (7)

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...

99MUSTANG5.3L

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.

Stev0n

iTrader: (7)

Does it matter which pedal you have? I have a vette pedal with truck app sensor in it. And the vette pedal has a lot less travel than the truck pedal

99MUSTANG5.3L

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.

Stev0n

iTrader: (7)

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.

BadWolf

is it possible to convert to drive by cable?

Stev0n

iTrader: (7)

It probably is if I buy a gas pedal, cable, another throttle body & get the computer redone.

But I need to run dbw for this setup & I don't have the money to buy all that extra stuff.

Mike_hawk

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.

Stev0n

iTrader: (7)

I've tested every wire at the throttle body with a multimeter & tried wiggling them with the same result. But I'll try this first thing in the morning.

Does anyone have any other advice outside of buying a new app sensor

Stev0n

iTrader: (7)

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.