Question about 2007 Chevrolet Colorado (Extended Cab) New Cars

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Pulse In Accelerator Pedal

There is a pesky pulse/tapping sensation in my accelerator. Problem is, it is intermittent and normally only happens on the highway. Have taken it to a dealer twice and they still havent fixed it.

Any suggestions

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  • rlowmaniii Sep 15, 2008

    I have the same problem, and it is intermittent. speed ranges from 15-60 mph. Gas pedal will vibrate and I feel a knocking on my foot. The truck has been in approximately 5 times for the same issue and they can't find a cause. GM has been contacted by the dealership without an answer. All I get from the dealership and GM is we don't know and we have never heard about this problem. If it gets worse come back, for what them to tell me the same thing?

  • Anonymous Nov 13, 2008

    My calipers were loose in my 2008 for some reason and it was causing pulsing over uneven ground which you could feel in the gas pedal.



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Is the cruise control activated when this occurrs? If so check cruise control linkage.

Posted on Sep 11, 2008

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Pontiac grand prix 2007 car shutting off, with Start disabled throttle control module.


It doesn't say module , Starting Disabled Due To Electronic Throttle Control !
The throttle actuator control (TAC) system delivers improved throttle response and greater reliability and eliminates the need for mechanical cable. The TAC system performs the following functions:
• Accelerator pedal position (APP) sensing
• Throttle positioning to meet driver and engine demands
• Throttle position sensing
• Internal diagnostics
• Cruise control functions
• Manage TAC electrical power consumption
The TAC system includes the following components:
• The APP sensors
• The throttle body assembly
• The powertrain control module (PCM)
Normal Mode
During the operation of the throttle actuator control (TAC) system, several modes or functions are considered normal. The following modes may be entered during normal operation:
• Minimum pedal value--At key-up, the powertrain control module (PCM) updates the learned minimum pedal value.
• Minimum throttle position (TP) values--At key-up, the PCM updates the learned minimum throttle position value. In order to learn the minimum throttle position value, the throttle blade is moved to the closed position.
• Ice break mode--If the throttle is not able to reach a predetermined minimum throttle position, the ice break mode is entered. During the ice break mode, the PCM commands the maximum pulse width several times to the throttle actuator motor in the closing direction.
• Battery saver mode--After a predetermined time without engine RPM, the PCM commands the battery saver mode. During the battery saver mode, the TAC module removes the voltage from the motor control circuits, which removes the current draw used to maintain the idle position and allows the throttle to return to the spring loaded default position.
Reduced Engine Power Mode
When the PCM detects a condition with the TAC system, the PCM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions:
• Acceleration limiting--The PCM will continue to use the accelerator pedal for throttle control, however the vehicle acceleration is limited.
• Limited throttle mode--The PCM will continue to use the accelerator pedal for throttle control however the maximum throttle opening is limited.
• Throttle default mode--The PCM will turn off the throttle actuator motor and the throttle will return to the spring loaded default position.
• Forced idle mode--The PCM will perform the following actions:
- Limit engine speed to idle by positioning the throttle, or by controlling the fuel and spark if the throttle is turned off.
- Ignore the accelerator pedal input.
• Engine shutdown mode--The PCM will disable fuel and de-energize the throttle actuator.

DTC P2101
DTC P2107
DTC P2108
DTC P2119
DTC P2120
DTC P2125
DTC P2135
DTC P2138 You need to see which of these codes

Nov 16, 2016 | 2007 Pontiac Grand Prix

2 Answers

Reduced engine power, service traction control, service stabilitrak


First of all a scan tool is need for this not a code reader, you need to view scan data after you find what code is stored in the PCM. It could have a problem with the powertrain control module, wiring, or the Accelerator Pedal Position (APP) Sensors. Here are a few codes that could set .
DTC P2120: Accelerator Pedal Position (APP) Sensor 1 Circuit

DTC P2122: Accelerator Pedal Position (APP) Sensor 1 Circuit Low Voltage

DTC P2123: Accelerator Pedal Position (APP) Sensor 1 Circuit High Voltage

DTC P2125: Accelerator Pedal Position (APP) Sensor 2 Circuit

DTC P2127: Accelerator Pedal Position (APP) Sensor 2 Circuit Low Voltage

DTC P2128: Accelerator Pedal Position (APP) Sensor 2 Circuit High Voltage

DTC P2138: Accelerator Pedal Position (APP) Sensor 1-2 Correlation

Oct 02, 2012 | 2008 Chevrolet Tahoe LS

1 Answer

Not all the time 50% the brakes have a grinding pulsing sensation they don't stop normal when this happens ant the brake pedal is very stiff. the rotors are not the problem nor the brake pads the rear...


I would like to learn something here. I understand what you are saying.

Question I have is--grinding,pulsing,don't stop normal and pedal very stiff.

I assume you personally removed the wheels and are familiar with your rotors etc.

I know your looking for answers, not being asked a question,but even ABS issues,power booster and other things excluded, you don't get grinding sounds and pulsing if there are no issues.

Just asking,so I can help as we go here.

Aug 06, 2010 | 2004 Ford Escape

1 Answer

ESP/ABS warning light comes on intermittently. Sometimes I feel an alarming sensation through the accelerator pedal.


have your abs system scanned at your local mechanic shop your brakes are nothing to mess with.

Mar 11, 2010 | 2004 Audi A4

1 Answer

I have an intermittent problem with my wipers. They don't work one day and the next they do. Could this be pulse board problem or with the motor?


more than likely the pulse board loose at the wire connector. try wiggling the connector with wipers on (keeping hands away from wipers) then try tapping the motor with a small hammer.

Feb 11, 2010 | 1999 Chevrolet Tahoe

1 Answer

Hyundai i30 Diesel automatic won't accelerate above idle at light


DOES THE ENGINE MIL WARNING LIGHT COME ON? WITH OUT MORE INFO YOU NEED TO CHECK MOTOR ON A CODE READER FOR STORED FAULTS, CHECK ALL AIR LINES TO EMMISION CONTROL, , SOUNDS LIKE YOU HAVE GONE INTO SAFE MODE, A SPLIT OR LEAKING PIPE ON THE INTERCOOLER IS A COMON FAULT ON THESE, IF YOU SWITCH ENGINE OF AND BACK ON QUICKLY WITH MOTOR RUNNING WITH OUT STALLING MOTOR AND IT CLEARS THEN IT IS PROBERLY THE SAFE MODE CUTING IN MEANING A FAULT HAS BEEN SEEN BY PCM

Dec 07, 2009 | 2008 Hyundai Elantra

2 Answers

I just bought a 2004 Nissan Frontier Crew Cab. The problem is a faulty cruise control, you press the on button ant it turns on in the dash board but it doesn't works you press the set button and it jut...


Call the dealer who sold you this car while it is still under warranty and insist that they repair it. The cruise control is quite a complex system and a scan is required to isolate the problem.

If you care to learn a bit more about the system read on:
Cruise control systems are comprised of electronic and mechanical subsystems. This is how they work.
We all know that the things that control the speed of the car are the gas pedal and the brakes. And the brain that normally controls the speed of the car is the brain of the driver. The driver senses the speed by looking at the speedometer and then adjusting the pressure on the gas pedal or the brakes to compensate for variations in the desired speed. The cruise control system does the same thing with one exception. It only controls the gas pedal - it doesn't even know there are brakes in the car!!
The vehicle's speed sensor which is mounted on the output shaft of the transmission (the thing that drives the wheels) sends electrical pulses to the computer, pulses which are generated by a magnet spinning past a sensor coil. When the vehicle's speed increases the frequency of the pulses increases. For any given speed of the vehicle there is a corresponding pulse frequency. It is this pulse frequency which the cruise control tries to maintain as a constant. You think of it as the vehicle's speed.
The brains of the control box of the cruise control has three functions. First, it stores the speed of the vehicle when you press the "set" button whild travelling at the desired speed. It keeps this value in its memory until you turn the ignition off. Second, it receives the pulses from the transmission sensor and compares the frequency of those pulses to the frequency value stored in its memory - the set point. Third, it sends pulses to a vacuum controlled diaphragm connected to the accelerator linkage. The pulses it sends regulates the amount of vacuum the diaphragm receives. The more pulses, the more vacuum and the more vacuum the more force on the accelerator linkage. The system continues to add vacuum force until the set point speed is reached. At that point the system modulates the amount of vacuum the diaphragm receives in an effort to maintain the number of pulses coming from the speed sensor as close to the stored value as possible.
OK, so this "brain" works just fine in controlling the speed of the vehicle until something goes wrong. What can go wrong?
First, the VSS, the thing that sends pulses to the brain might fail. Normally the speedometer also fails so that's pretty easy to diagnose.
Next, the power to the brain can be interrupted. A blown fuse or a corroded connector can prevent the brain from working correctly or at all.
Next, the brains can lose its ability to function. A faulty component can prevent the brain from doing its thing. The brain is a pretty sophisticated box that contains a lot of electronic components including a microprocessor. NOrmally when the brains fail you need to replace the box..
The vacuum diaphragm can develop a leak. If that happens then the cruise control might set and hold the speed for some time however if the leak is larger than the supply line and modulator can add vacuum to the system the system will slowly lose control and the vehicle will slow down. This can also happen if the vacuum line to the diaphragm is cracked or loose.
Finally, the linkage that connects the diaphragm to the accelerator linkage can fail. Some aftermarket cruise control systems use a short length of what looks like fat key chain - bead chain. I have seen several units fail when the chain simply breaks.
Diagnosis of a failed system can be a complex process. Most vehicle shop manuals have a multi-page diagnostic flow chart that the dealer mechanics use to solve failures. If there isn't an obvious problem like a broken wire, a blown fuse or a leaking vacuum line then the problem most likely lies in the brains of the unit or in the switch that sets the speed and contains the other functions of resume and accelerate. Most cruise control switches are on the directional signal stem, a multifunction switch assembly with fine wires that break due to the constant motion of the wires as you use the directionals in your daily travels.

Nov 04, 2009 | Nissan Frontier Cars & Trucks

1 Answer

Abs brakes pulse when stopping and light is on


Normally a pulsing brake pedal indicates that the rotors have warpped. They can be turned, but it will happen again since turning them makes them thinner. Replace is probably the best solution.

Oct 20, 2009 | 1999 Ford Expedition

2 Answers

Check the accelerator position sensor on the pedal!


If this is what I think it is, on the 3.5 Lit V6, you have an APS (Accelerator Position Sensor) and a TPS (Throttle Position Sensor). The accelerator pedal cable is NOT directly connected to the throttle body plate, it's connected to the APS. The APS sends its signal to the ETSCM (Electronic Throttle System Control Module) which in turn activates the ETS Motor located on the throttle body which opens/closes the throttle plate/butterfly. It's a very sofisticated electronic system. Both the APS and the TPS are known to go bad and simply replacing them is no guarantee of fixing problems in this system (often times it does, and frequently it doesn't). You should first verify there is a problem with these sensors (APS and or TPS). They are basic potentiometers (two circuits in each) which provide data to the computer regarding throttle opening for LOAD calculations (ignition timing, fuel injector pulse width, cruise control operation, etc). Best you have this system diagnosed by a professional technician who knows the system.

Jun 03, 2009 | 2004 Hyundai Santa Fe

1 Answer

Fiat Stilo intermittant loss of power


How old is the car? Have you tryed fuel injection cleaner? Is it well you speeding up?

May 13, 2009 | Fiat Pininfarina Cars & Trucks

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