Feb 222016

2009 Chevy Traverse
I have Code P0752 on my Chevrolet Traverse 2009 with transmission problems , fault codes P0752 , P0989 , P0877,
I want to replace the valve body with TCM & speed sensors.
My question: is reprogramming required after installation?

Yes, the new TCM requires reprogramming.

Code P0752 – 1-2 Shift Solenoid Valve Performance – No Second or Third Gear

Code P0752 Possible causes

– Low transmission fluid level
– Dirty transmission fluid
– Faulty 1-2 Shift Solenoid valve
– 1-2 Shift Solenoid valve harness or connectors
– 1-2 Shift Solenoid valve circuit is open or shorted

Code P0752 Description

The 1-2 shift solenoid (SS) valve controls the fluid flow acting on the 1-2 and 3-4 shift valves. The 1-2 SS valve is a normally-open exhaust valve that is used with the 2-3 SS valve, in order to allow four different shifting combinations.

Code P0752 is detected when

The P0752 code is detected when the gear required by the ECM does not match the actual gear when vehicle is driven.

Code P0752 Related symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Transmission will not shift gears.

transmission temperature chart

P0989 – Transmission Fluid Pressure Sensor/Switch E Circuit Low
P0877 – Transmission Fluid Pressure Sensor/Switch D circuit Low

Feb 112016

TPS Code for 2009 Chevy Aveo
Has 78,000 miles. New coil pack, battery, plugs, air filter. Only when its cold it has rough idling when started. It throws a TPS code, we have cleaned it numerous times but its really done nothing. There are times I lose all power when driving and no response from gas pedal. Ive read this car has had a lot of similar issues. But I cant afford to play a guessing game.


Hopefully it is as simple as performing the relearn procedure after cleaning. Idle relearn below. If not you may be looking at replacing the entire unit. You can pick one up here for about $140 including shipping.

TPS Code Throttle Body 2009 Chevy Aveo

TPS Code

P0122 – Throttle Position Sensor 1 Circuit Low Voltage

TPS Code Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Rough idle
– Loss of power when driving

TPS Code Possible Causes

– Faulty throttle position sensor
– Throttle position sensor harness is open or shorted
– Throttle position sensor circuit poor electrical connection

Throttle Actuator Control (TAC) System Description

The throttle actuator control (TAC) system is used to improve emissions, fuel economy, and drive-ability. The TAC system eliminates the mechanical link between the accelerator pedal and the throttle plate. The TAC system eliminates the need for a cruise control module and idle air control motor. The following is a list of TAC system components:

• The accelerator pedal assembly includes the following components:

– The accelerator pedal
– The accelerator pedal position (APP) sensor 1
– The APP sensor 2

• The throttle body assembly includes the following components:

– The throttle position (TP) sensor 1
– The TP sensor 2
– The throttle actuator motor
– The throttle plate

• The engine control module (ECM)

The ECM monitors the driver demand for acceleration with 2 APP sensors. The APP sensor 1 signal voltage range is from about 0.5-4.5 volts as the accelerator pedal is moved from the rest pedal position to the full pedal travel position. The APP sensor 2 range is from about 0.3-2.2 volts as the accelerator pedal is moved from the rest pedal position to the full pedal travel position. The ECM processes this information along with other sensor inputs to command the throttle plate to a certain position.

The throttle plate is controlled with a direct current motor called a throttle actuator control motor. The ECM can move this motor in the forward or reverse direction by controlling battery voltage and/or ground to 2 internal drivers. The throttle plate is held at a 5.7 degree rest position or the un-powered position using a constant force return spring. This spring holds the throttle plate to the rest position when there is no current flowing to the actuator motor.

The ECM monitors the throttle plate angle with 2 Throttle Position Sensors. The TP sensor 1 signal voltage range is from about 0.95-4.35 volts as the throttle plate is moved from idle to wide open throttle (WOT) position. The TP sensor 2 voltage range is from about 4.05-0.65 volts as the throttle plate is moved from idle to WOT position.

The ECM performs diagnostics that monitor the voltage levels of both APP sensors, both TP sensors, and the TAC motor circuit. It also monitors the spring return rate of the return springs that are housed internal to the throttle body assembly. These diagnostics are performed at different times based on whether the engine is running, not running, or whether the ECM is currently in a throttle body relearn procedure.

Every time the ignition cycle is cycled OFF, the ECM performs a quick throttle return spring test to make sure the throttle plate can return to the 7 percent rest position from the 0 percent position. This is to ensure that the throttle plate can be brought to the rest position in case of an actuator motor circuit failure. Observe, under cold conditions, the ECM commands the throttle plate to 0 percent with the ignition ON and the engine OFF to release any ice that may have formed on the throttle plate.

Throttle Body Relearn Procedure

The engine control module (ECM) stores values that include the lowest possible throttle position (TP) sensor positions and the rest positions. These values will only be erased or overwritten if the ECM is reprogrammed or if a throttle body relearn procedure is performed. Observe, if the battery is disconnected, the ECM will immediately perform a throttle body relearn procedure when the ignition is turned ON.

The ECM performs a relearn procedure twice and compares the results. If the results are nearly the same, the values are stored and the learn procedure is complete. The following is when the ECM performs a learn procedure:

• The ignition is ON.
• The engine is cranking.
• Deceleration
• The ignition is cycled OFF.

The ECM performs the learn procedure every 15 ignition cycles.

The ECM commands the throttle plate from the rest position to full closed, then stores TP sensor 1 and 2 voltages. This procedure takes less than 1 second. If any faults occur in the throttle actuator control (TAC) system, a DTC sets.

TAC System Default Actions/Reduce Power Modes

There are 4 reduce power modes that the engine control module (ECM) can default to if an error is detected in the throttle actuator control (TAC) system. The ECM monitors for the following conditions:

• Accelerator pedal position (APP) sensor 1 or 2 circuit fault
• APP sensor correlation fault
• A 5-volt reference circuit fault
• Battery voltage is less than 8 volts or greater than 24 volts.

If the ECM detects any of the above conditions, the ECM enters a Limited Performance reduced power mode. In the Limited Performance mode, the engine torque is limited. The ECM remains in this reduced power mode during the entire ignition cycle even if the fault is corrected. Usually accompanied with a TPS Code.

If there is no APP sensor information, the system enters a Forced Idle reduced power mode. In the Forced Idle mode, the ECM uses a default APP sensor position that is calculated from the brake switch, transmission gear position, and vehicle speed. The vehicle can be driven up to 32 km/h (20 mph) in this mode be engaging the transmission into gear and releasing the brake pedal.

If there is a condition with the TAC circuits, throttle actuator command vs actual position fault, or a TP sensor 1 or 2 circuit fault, the ECM enters a Power Manage reduced engine power mode. In the Power Manage mode, the throttle plate is not controlled. The engine torque is controlled to the desired value using cylinder shutoff and spark retard. The engine will idle or cruise with 2 cylinders enabled and accelerate with all 4 cylinders. Usually accompanied with a TPS Code.

If the ECM detects a severe failure in the TAC system, the ECM enters a Forced Shutdown mode. In this mode, the ECM disables the TAC system, the fuel system, and the ignition system so the engine will not start. The Forced Shutdown mode occurs when the ECM detects a severe internal ECM condition, the throttle plate is stuck open, or a large intake manifold vacuum leak is detected. Usually accompanied with a TPS Code.

Idle Relearn

When do I need to relearn the idle

The Idle Learn Procedure listed below must be performed whenever the following occurs:

• The throttle body assembly is replaced
• The throttle body is cleaned
• The engine control module (ECM) is replaced
• The idle air control valve (IAC) is replaced
• Power disconnection (battery cable, ECM fuse, etc.) (Delphi ECM only)

Idle Relearn Procedure

•Turn the ignition ON.
•Turn the ignition OFF for 15 seconds.
•Turn the ignition ON for 5 seconds.
•Turn the ignition OFF for 15 seconds.
•Start the engine in park/neutral.
•Allow the engine to run until the engine coolant temperature is greater than 85°C (185°F).
•Turn the A/C ON for 10 seconds, if equipped.
•If the vehicle is equipped with an automatic transaxle, apply the parking brake. While pressing the brake pedal, place the transaxle in drive (D) for 10 seconds.
•Turn the A/C OFF for 10 seconds, if equipped.
•If the vehicle is equipped with an automatic transaxle, while pressing the brake pedal, place the transaxle in park/neutral.
•Turn the ignition OFF. The idle learn procedure is complete.

Jan 092016

2007 Chevy Impala
I have an 2007 Chevy Impala with the 3.5L engine. I have no heat at all. The car will get to operating temp and not overheat. Both radiator hoses are hot and squishy and both heater hoses are hot and stiff. I’m at a loss


Having a no heat situation can be a serious issue in the winter months. You have done well so far in your diagnosing. You have eliminated almost all of the heating system. The coolant is getting up to temperature and flowing through the heater core as it should. If you are hearing the heater blower motor coming on then all you are left with is the ventilation system. This system has an actuator that control the air temperature door. I would suspect the actuator to be at fault.

No heat in car but air is blowing

  • Remove the screws that secure the air temperature actuator to the HVAC module assembly upper case.
  • Remove the air temperature actuator from the HVAC module assembly upper case.


No Heat

Air Temperature Door Actuator for 2007 Chevy Impala

I have double checked to insure this part will fit and is a GM-recommended replacement part for your GM vehicle’s original factory component. Less than $30 and includes free shipping.

Follow image for more Details…

Jan 042016

2003-Chevy Tahoe
I have a 2003 Chevy Tahoe. After changing the oil, tire kingdom forgot to reset oil change light also know as the oil life indicator light. They told me how to reset it by turn on the power and pumping the gas pedal four times. A message came up by I cant remember what it said. I turned the car off and didn’t use it til the next day. When I started the Tahoe I had to give it gas to keep it running. I went to leave but it was running really bad acting like it wanted to shut off. When I was stopped I had to rev it up to keep it running. What could be wrong and does it have to do with me resetting the oil light?

Having to reset oil change light is a non intrusive procedure that should bear no effect on the drivability of the engine whatsoever. The procedure simple resets the oil change indicator light.

reset oil change light

How to reset oil change light

  1.  To reset engine oil life monitor and turn odd CHANGE OIL light (or message), turn ignition to ON position with the engine off.
  2. Depress accelerator pedal to wide open throttle 3 times within 5 seconds.
  3. Turn ignition to LOCK/OFF
  4. If light (or message) does not turn off, turn ignition OFF and repeat procedure.
Jan 042016

1997 Chevy Suburban
The rear axle assembly disintegrated on my 97 4wd suburban lt. And more than likely the rear drive train needs to be replaced just need to know how much to fix this, ballpark.


$1600 – Rebuilt Rear end installed (Rear Axle Assembly)

*Jasper Engines and Transmissions also re-manufacturer rear ends. I mention this because they have one of the best warranties out there. They will cover your part and LABOR cost should anything occur.  Not to mention they have Installers all over the country.

Rear Axle  Assembly Replacement

  1. Raise and support the front end on jackstands.
  2. Remove the wheels.
  3. Remove the skid plate.
  4. Drain the carrier.
  5. Matchmark and remove the front driveshaft.
  6. Disconnect the right axle shaft at the tube flange.
  7. Disconnect the left axle shaft at the carrier flange.
  8. Wire both axle shafts out of the way.
  9. Unplug the connectors at the indicator switch and actuator.
  10. Disconnect the carrier vent hose.
  11. Remove the axle tube-to-frame bolts, washers and nuts.
  12. Remove the lower carrier mounting bolt.
  13. Disconnect the right side inner tie rod end at the relay rod.
  14. Depending on the model, it may be necessary to remove the engine oil filter.
  15. Support the carrier on a floor jack
  16. Remove the upper carrier mounting bolt.
  17. Lower the carrier assembly from the truck.

To install:

  1. Raise the carrier into position.
  2. Install the upper carrier mounting bolt, washers and nut. Then, install the lower carrier mounting bolt, washers and nut. Tighten the bolts to 80 ft. lbs. (110 Nm).
  3. Remove the jack.
  4. Install the oil filter.
  5. Connect the tie rod end. Tighten the nut to 35 ft. lbs. (47 Nm).
  6. Install the axle tube-to-frame bolts, washers and nuts. Tighten the nuts to 75 ft. lbs. (100 Nm) for 15 and 25 series; 107 ft. lbs. (145 Nm) for 35 series.
  7. Connect the vent hose.
  8. Connect the wiring.
  9. Connect the axle shafts at the flanges. Tighten the bolts to 59 ft. lbs. (80 Nm).
  10. Connect the driveshaft. Tighten the bolts to 15 ft. lbs. (20 Nm).
  11. Fill the carrier with gear oil.
  12. Install the wheels.
  13. Add any engine oil lost when the filter was removed.


Dec 302015

My Monte has almost 150,000 mi. on it. At 135,000 it had a full transmission service done, as indicated. In the last 2 months I have noticed it clunking when shifting from 1st to 2nd, then kind of slipping then grabbing when going from 2nd to 3rd. It mostly happens in the city when stopping and going a lot and in colder weather. It has started to become more frequent here lately. I have a sealed transmission so no fluids are ever added, and it is a 6 cylinder. Is my transmission failing?

Dec 182015

turn on headlights and blows a fuse
need to know what to check to find what is causing blowing fuses when turn on headlights