Have a scan tool hooked up , not a code read or what they use at the auto part stores . Need a factory tech2 or someother professional type that can check for DTC'S - diagnostic trouble codes in all the modules . Could be as simple as a loose ground connection , checking codes could point to the problem . Do you know what all the codes are ? P codes - engine & transmission ,B codes - body control module , C - chassie - ABS ,U codes - data communication network codes . This is something you should have a qualified repair shop check .
REDUCED POWER
Refer to:
• Powertrain Control Module Description for the 2.8L engine
• Powertrain Control Module Description for the 3.5L engine
Throttle Actuator Control (TAC) System
Throttle Actuator Control (TAC) Overview
The throttle actuator control (TAC) system uses vehicle electronics and components to calculate and control the position of the throttle blade. This eliminates the need for a mechanical cable attachment from the accelerator pedal to the throttle body. This system also performs the cruise control functions as well.
The TAC system components include, but are not limited to the following:
• The accelerator pedal position (APP) sensors
• The throttle body
• The powertrain control module (PCM)
Each of these components interface together to ensure accurate calculations and control of the throttle position.
Accelerator Pedal Position (APP) Sensor
The accelerator pedal position (APP) sensor is mounted on the accelerator pedal assembly. The APP is 2 individual APP sensors within one housing. There are 2 separate signal, low reference, and 5-volt reference circuits. APP sensor 1 voltage increases as the accelerator pedal is depressed. APP sensor 2 voltage decreases as the accelerator pedal is depressed.
Throttle Body Assembly
The throttle body for the throttle actuator control (TAC) system is similar to a conventional throttle body with several exceptions. One exception being the use of a motor to control the throttle position instead of a mechanical cable. Another exception is the throttle position (TP) sensor. The TP sensor is mounted in the throttle body assembly. The TP sensor is 2 individual TP sensors within the throttle body assembly. Two separate signals, low reference, and 5-volt reference circuits are used to connect the TP sensors and the powertrain control module (PCM). TP sensor 2 signal voltage increases as the throttle opens. TP sensor 1 signal voltage decreases as the throttle opens.
Reduced Engine Power Mode
When the PCM detects a problem with the throttle actuator control (TAC) system the PCM enters one of the following Reduced Engine Power Modes:
• Acceleration Limiting--The control module will continue to use the accelerator pedal for throttle control, however the vehicle acceleration is limited.
• Limited Throttle Mode--The control module will continue to use the accelerator pedal for throttle control, however the maximum throttle opening is limited.
• Throttle Default Mode--The control module will turn OFF the throttle actuator.
• Forced Idle Mode--The control module will perform the following actions:
- Limit engine speed to idle by positioning throttle position, or by controlling fuel and spark if throttle is turned OFF.
- Ignore accelerator pedal input.
• Engine Shutdown Mode--The control module will disable fuel and de-energize the throttle actuator.
Have you had it checked for DTC'S - diagnostic trouble codes ?
DTC P2176
The commanded throttle position (TP) is compared to the actual TP. Both values should be within a calibrated range of each other. The powertrain control module (PCM) continuously monitors the commanded and actual TPs. If the values are greater than the calibrated range, DTC P2176 sets.
--------------------------------------------------------------------------------
DTC P2138
The accelerator pedal position (APP) sensors 1 and 2 are located within the accelerator pedal assembly. Each sensor has the following circuits:
• A 5-volt reference circuit
• A low reference circuit
• A signal circuit
This provides the powertrain control module (PCM) with a signal voltage proportional to accelerator pedal movement. The APP sensor 1 signal voltage at rest position is near the low reference and increases as the pedal is actuated. The APP sensor 2 signal voltage at rest position is near the 5-volt reference and decreases as the pedal is actuated.
DTC P2135
The throttle actuator control (TAC) assembly has 2 throttle position (TP) sensors mounted within the assembly. The powertrain control module (PCM) provides individual signal, ground, and 5-volt reference circuits to each sensor. Both sensors operate within a voltage range between 0.35-4.65 volts. When the throttle is opened from 0-100 percent, one sensor signal voltage increases while the other decreases. The signal circuit for TP sensor 1 is referenced to ground, and the signal circuit for TP sensor 2 is pulled up to 5 volts within the PCM.
DTC P2128
DTC P2127
DTC P2125
DTC P2123
Drive by Wire Function and diagnostics by Wells
I guess it's just me, but, I don't like taking battery cables loose. I know sometimes it works.
Did you check voltage at proper fuse circuits, use a testlite.
You may have to check proper wire colors in wire harness on hinge side of driver door. You open and shut the driver door so much, sometimes those wires break. I'm talking voltage and ground. The info I looked at was for two door version.
Hi, if i understand you, do you have to crank the engine over, but it doesnt ignite and run. But if you come back in 10 min. It cranks and starts. First, is this issue happening if the engine is cold or when it warmed up. One of my trix to see of you have a fuel or ign Issue is spray some starting fluid in the air cleaner. If it starts then you have a fuel issir. Of it doesnt its am ogn Issue Hope that helps
Hi, to change the bulbs in the taillight assembly you have to access it from inside the vehicle. If there is no access panal then uou have to remove the panal to gain access to the bulb recepticle. Usually its apx 1/4 turn or so to remove it. Now you can remove the bulb and install the new one.
I would bet u have high impedance in your batt. Cables. Ez to check if u have an ohm meter. Put ur metor on the lowest ohms setting. Touch ur leads together, see the voltage reading , like 002 for example. Disconnet the batt. From the cables. Read the resistance from one end of the same lead to the other. If ur reading is more than .002 or lower your cables are bad. Your problem is a classic issue of what you have. Hope that helps.
hello,
first thing is to check all your fuses and make sure that they are all good? the next thing is to check if you are getting tachometer signal as you turn over the engine? if you are not getting tach signal the you should change the (crank sensor) in order to make the engine gets spark and the fuel pump to operate. if that does not work then you have a wiring problem and or possibly a bad ignition switch or computer malfunction.
Sometimes condensation will build up on your oil cap...So a milky substance on your cap doesn't necessarily mean you have a blown head gasket. Check your dipstick to see if it looks like chocolate milk. If it does, then you might have a cracked block or head gasket issue.
If you mean mirror, for most vehicles it is the same. There is a plastic plate on the inside of the vehicle, you will have to carefully pry it off. You may need a screwdriver, and it may be glued down, each vehicle is slightly different. Once removed, there will be between two and four screws. Remove all the screws (while holding the mirror with your other hand) and the mirror will come off. Now reverse the process to put the new one on. You will have to be careful of the wires/cables for adjusting it, make sure you put them back the way they were on the old one.
I do not know about your specific truck, but I had this trouble once, and what I did was open up the ignition switch (it's just 3 screws holding it on), remove the "cover" that only allows the key to go in, put it all back together, and used a screwdriver to turn it on/off until I was able to get a replacement switch.
Ok tell me this is the pedal stuck all the down on the e-brake. If so if you look under the dash on the e-brake follow the pedal and you can see where it locks and all yo have to do is press pedal and with a screw driver release lock on the pedal. Good luck
http://parts.nalleygmc.com/showAssembly.aspx?ukey_assembly=392045&ukey_product=2577448
