ETC won't work
Thread Starter
Teching In
Joined: Nov 2011
Posts: 11
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From: Big Sky Country
ETC won't work I just got my jet boat running with 2004 LQ4. The Engine will start and idle fine. The ETC won't work, as soon as I turn the key ON the throttle blade goes closed and back to 19% and sets the following codes.
[PCM] P1125 - APP System (SES) (Pending) (Old) (History) (Current) (Immature)
[PCM] P1516 - Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance (History) (Immature)
[PCM] P2120 - Throttle/Pedal Position Sensor/Switch D Circuit (Pending) (Old) (History) (Current) (Immature)
[PCM] P2125 - Throttle/Pedal Position Sensor/Switch E Circuit (Pending) (Old) (History) (Current) (Immature)
The accelerator pedal has no effect on the throttle blade.
All the components are from the same donor truck. I tried a different APP sensor and no change. I have read and searched lots of threads and haven't found any solution.................. Any Ideas....?
[PCM] P1125 - APP System (SES) (Pending) (Old) (History) (Current) (Immature)
[PCM] P1516 - Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance (History) (Immature)
[PCM] P2120 - Throttle/Pedal Position Sensor/Switch D Circuit (Pending) (Old) (History) (Current) (Immature)
[PCM] P2125 - Throttle/Pedal Position Sensor/Switch E Circuit (Pending) (Old) (History) (Current) (Immature)
The accelerator pedal has no effect on the throttle blade.
All the components are from the same donor truck. I tried a different APP sensor and no change. I have read and searched lots of threads and haven't found any solution.................. Any Ideas....?
I just got my jet boat running with 2004 LQ4. The Engine will start and idle fine. The ETC won't work, as soon as I turn the key ON the throttle blade goes closed and back to 19% and sets the following codes.
[PCM] P1125 - APP System (SES) (Pending) (Old) (History) (Current) (Immature)
[PCM] P1516 - Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance (History) (Immature)
[PCM] P2120 - Throttle/Pedal Position Sensor/Switch D Circuit (Pending) (Old) (History) (Current) (Immature)
[PCM] P2125 - Throttle/Pedal Position Sensor/Switch E Circuit (Pending) (Old) (History) (Current) (Immature)
The accelerator pedal has no effect on the throttle blade.
All the components are from the same donor truck. I tried a different APP sensor and no change. I have read and searched lots of threads and haven't found any solution.................. Any Ideas....?
[PCM] P1125 - APP System (SES) (Pending) (Old) (History) (Current) (Immature)
[PCM] P1516 - Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance (History) (Immature)
[PCM] P2120 - Throttle/Pedal Position Sensor/Switch D Circuit (Pending) (Old) (History) (Current) (Immature)
[PCM] P2125 - Throttle/Pedal Position Sensor/Switch E Circuit (Pending) (Old) (History) (Current) (Immature)
The accelerator pedal has no effect on the throttle blade.
All the components are from the same donor truck. I tried a different APP sensor and no change. I have read and searched lots of threads and haven't found any solution.................. Any Ideas....?
You may notice that only 1/2 the travel of an APP makes throttle go wide open. I had one install that the gas pedal was just too high, and uncomfortable to drive. I was able to adjust the stop on the throttle, and moved the gas pedal 1/2 way down, and then used the bottom half of the travel. The TAC/PCM learns minimum position after a few key cycles.
Good luck, please report back what you find.
Are you still running the base Truck Tune?
Jon
PSI
Jon
PSI
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Thread Starter
Teching In
Joined: Nov 2011
Posts: 11
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From: Big Sky Country
The only thing I've changed from the base tune is VATS disabled and all inapplicable DTC's. I will try the pedal @ rest adjustment tonight. The weird thing is I unbolted the complete pedal assembly out of my 2003 GMC daily driver and plugged it in and it did not change the problem. Maybe it did not like the at rest value of that pedal either? BTW I use HP Tuners. I will try some things tonight, Thanks Guys.
Is the TCC/Brake switch wire hooked up and is the check engine light hooked up?
Jon
PSI
Jon
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Thread Starter
Teching In
Joined: Nov 2011
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From: Big Sky Country
Hook up your check engine light and the brake switch wire. Throttle should work. You shouldnt need a vss.
Jon
PSI
Jon
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Teching In
Joined: Nov 2011
Posts: 11
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From: Big Sky Country
Ok I hooked up a MIL negative from PCM positive from constant power, TCC wire to constant positive, and pin-6 from TAC (brake lamp proof) through resistance to ground. The MIL works as I can command it On or OFF. I can clear DTC's but they instantly return.
[PCM] P1125 - APP System (SES) (Pending) (Old) (History) (Current) (Immature)
[PCM] P2120 - Throttle/Pedal Position Sensor/Switch D Circuit (Pending) (Old) (History) (Current) (Immature)
[PCM] P2125 - Throttle/Pedal Position Sensor/Switch E Circuit (Pending) (Old) (History) (Current) (Immature)
[PCM] P1125 - APP System (SES) (Pending) (Old) (History) (Current) (Immature)
[PCM] P2120 - Throttle/Pedal Position Sensor/Switch D Circuit (Pending) (Old) (History) (Current) (Immature)
[PCM] P2125 - Throttle/Pedal Position Sensor/Switch E Circuit (Pending) (Old) (History) (Current) (Immature)
per alldata
P2120
Sets when APP sensor 1 voltage is below 0.24v or above 4.49v
or
5 volt reference circuit is less then 4.54v or more then 5.21v
P2125
This code is the same as P2120, except deals with APP sensor 2 circuit.
P1125 sets when the difference between APP 1 and APP 2 are more then a predicted value.
Diagnostic flow chart shows check P2120, P2125 before dealing with P1125, whatever is causing the 212x codes, is likely also causing the P1125.
You need to find the PID for raw APP sensor voltage on HP Tuners. See what the voltage reads, and see if it falls in the range listed above.
You may also check with a digital volt meter, attached is schematic for 2004 drive by wire pedal to tac module wiring.
Also, make sure your gas pedal harness is wired correct, note that E & J are crossed at each end, all the other pins are A to A, B to B and so on.
Also, I've noticed the 03+ truck pedal harnesses only have APP 1 and APP 2, even though the schematics show APP 3, the harness should only have 6 wire on it.
P2120
Sets when APP sensor 1 voltage is below 0.24v or above 4.49v
or
5 volt reference circuit is less then 4.54v or more then 5.21v
P2125
This code is the same as P2120, except deals with APP sensor 2 circuit.
P1125 sets when the difference between APP 1 and APP 2 are more then a predicted value.
Diagnostic flow chart shows check P2120, P2125 before dealing with P1125, whatever is causing the 212x codes, is likely also causing the P1125.
You need to find the PID for raw APP sensor voltage on HP Tuners. See what the voltage reads, and see if it falls in the range listed above.
You may also check with a digital volt meter, attached is schematic for 2004 drive by wire pedal to tac module wiring.
Also, make sure your gas pedal harness is wired correct, note that E & J are crossed at each end, all the other pins are A to A, B to B and so on.
Also, I've noticed the 03+ truck pedal harnesses only have APP 1 and APP 2, even though the schematics show APP 3, the harness should only have 6 wire on it.
Last edited by busta9876; Apr 11, 2012 at 07:56 PM.
Thread Starter
Teching In
Joined: Nov 2011
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From: Big Sky Country
Well no luck. I have verified positive 5 volts on reference wires both sensor 1 and 2 low reference to ground is good on sensor 1 and 2. I checked continuity on serial data wires from PCM to TAC module. All values were checked with DMM @ APP end of harness. I can't see voltage through HP Tuners scanner????? I also checked resistance from TAC module end of harness to APP. Both sensor 1 and 2 have nice sweep with pedal but sensor 2 resistance is consistently about 1100 ohms lower than sensor 1. Both sensor circuits ( 5 volt to signal ) have higher resistance at rest than full throttle. I can't prove the TAC module is bad so I hate to just throw parts at it. And like I said ALL the components came from the same donor truck. What gives????
Pin 6 goes to switched power through brake switch. Same a TCC clutch.
Jon
PSI
Jon
PSI
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try and get your hands on another TB, just unhook your old one, plug it in to the new one and see if it operates without the engine running(key to run positon but not running)
Thread Starter
Teching In
Joined: Nov 2011
Posts: 11
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From: Big Sky Country
I just swapped TB with the one on my truck and the one from the boat works on the truck. I did the same thing with the TAC module and it worked also. I must have a wiring or tuning problem, but what?
Thread Starter
Teching In
Joined: Nov 2011
Posts: 11
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From: Big Sky Country
Wooohoooo!!!! I figured it out after all the BS extra wires I thought I needed, busta9876 was wright on. The APP only uses about the middle half of its travel to open the throttle blade to WOT. And I had my pedal set up to use all the travel. I played with shimming the pedal at rest ( clearing the codes every key cycle) until the PCM liked the value at rest and wallah it worked, but if I go full throttle the TB closes and the codes return. All I have to do now is make a stop at full throttle ( at the TB) before APP full throttle.
BTW I did not need any extra wires mentioned above.
As far as the other APP that I tried not working, I had not cleared the codes with my scanner before trying it
Thanks for all the help guys.
BTW I did not need any extra wires mentioned above.
As far as the other APP that I tried not working, I had not cleared the codes with my scanner before trying it
Thanks for all the help guys.
