This 2003 Chevrolet Tahoe with a 5.3 liter engine came in with the customer complaint of the reduced power display was on and the vehicle could not be driven more than about 30 mph. Checking codes found a code p1516 stored for Predicted VS. Actual Throttle Position Correlation Error. That is fancy computer talk for the computer expects the TPS to be in one position and it sees the TPS in another position. There are several things that can cause this condition but by far the most common is a faulty throttle body assembly. I have noticed a disturbing trend in these vehicles in that the last few that I have had to change I also found very weak batteries and the weaker the battery is during cranking the more pronounced the symptom. If the key was left on in these vehicles for more than about five to ten minutes (the time it takes to hook up a scanner and check computer codes and relative data), the starter would turn the engine over very slowly (indicating a weak battery) and sometimes the battery would have to be jumped to start the engine. I may be wrong but it is my belief that a weak battery condition during cranking may be leading to premature failure of the throttle body assembly. My personal philosophy on late model highly computerized vehicles is to replace the battery every three to five years regardless and of course use a good battery and not the cheapest you can find.
Anyways on to changing the throttle body assembly. First remove the upper engine trim cover by first removing the screw and lift off.
Next remove the intake tube that connects to the mass air flow sensor.
Now the intake hose from the throttle body assembly.
Disconnect the clip that holds the intake hose assembly to the radiator hose.
Remove the harness connector from the throttle body by first pulling the gray locking clip back. Depress the lever and remove the connector. Inspect the yellow wire for possible damage as it too can cause the problem, although it seems to be more of a problem in the full sized vans.
There are three nuts that have to be removed.
Next the coolant lines have to come off but first I clamped them both off with hose clamp pliers. Then I took the coolant hose spring clamp and moved it back down the hose so that I could remove the hose from the throttle body. One could use pliers with a little luck and a lot of frustration it will move.
After the hose, next to the alternator is removed the throttle body can be repositioned to make the rest of the job easier.
Off with the old and on with the new. First the passenger side hose is installed. Then the throttle body assembly is put back in place and the driver’s side hose is reattached. In the following picture you can see that I used two pair of hose clamp pliers for the job. It saves having to drain the coolant system and time is money.
Now it is time to put the hose clamp back in place.
The new throttle body is now installed and ready for the intake hose and top trim cover to be replaced.
173 discussions on “Reduced Power Displayed 2003 Chevrolet Tahoe”
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yes sir cleaned/ replaced eyelets on both sides. i purchased an aftermarket TB already and just for the heck of it i put the original back on, same situation. mile down the road REP. i’m ready to just find a ditch with this thing 🙁
These are the conditions for setting the P1516 code according to GM Service Information.
The TAC module detects that the predicted and the actual throttle positions are not within a calibrated range of each other.
The PCM and the TAC cannot determine the throttle position.
Both of the TP sensors are invalid.
All of the above conditions are met for more than 1 second.
From the list of parts that you have already replaced, logic would dictate that the wiring harness, PCM or one of the parts you already have replaced is faulty.
I believe that AC Delco has the throttle bodies on national back order and the aftermarket ones are questionable at best.
I hate to ask again but did you check the ground on the top rear of the engine, passenger side? You did not state specifically if you did or did not.
no other codes, reader only shows p1516. i replaced the eyelets on the grounds(didn’t look great) and replaced the ground strap on the drivers side.
not sure if this will help at all but reader pulled this from truck.
Parameter Description Results
DTC for which Freeze Frame was Stored P1516
Fuel System 1 Status Closed Loop
Fuel System 2 Status Closed Loop
Calculated LOAD Value 22.35 %
Engine Coolant Temp 186.80 °F
Short Term Fuel Trim – Bank 1 -1.56 %
Long Term Fuel Trim – Bank 1 4.69 %
Short Term Fuel Trim – Bank 2 -2.34 %
Long Term Fuel Trim – Bank 2 4.69 %
Intake Manifold Absolute Pressure 16.29 inHg
Engine RPM 1,840.25 rpm
Vehicle Speed Sensor 52.82 mph
Air Flow Rate Mass Air Flow Sensor 8.04 lb/min
Absolute Throttle Position 32.16 %
Are there any other codes stored? Did you check the ground at the top rear of the engine?
I too am getting the REP p1516, replaced the TB, pigtails, peddle sensor and TAC module, yesterday cleaned the grounds replaced the ends not sure what more I can do. I got a miledown the road and REP yet again , owned the truck a year and loved it,now not so much any help would be greatly appreciated.