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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I understand the need to try and resolve the problem immediately. However if possible when the problem returns try and get a trouble code.
so i did something stupid at the car was the engine cleaner sprayed it on the engine and rinsed now 2 days later check engine light came on and says reduced engine power on my 4.8 liter 2003 chevy tahoe next day reduced engine power was off but check engine light on i unhooked battery and reattached everything was normal any suggestions if comes back on?
My first thought would be that something did not go quite right with the speed sensor replacements. Missing speed sensor data can cause shifting issues. I would check for damaged wiring or terminals at the speed sensors that were replaced. Several other things also come to mind when factoring in hitting bumps. There is a ground connection and the top rear of the engine that could be starting to fail. If you have a factory floor mounted center console there is also a rub spot where the wiring harness goes under a steel brace. Front edge on the driver’s side. You need a mirror to see it without disassembling.
Sparky, I took my 2003 Tahoe to a shop today to have the transmission fluid changed. I also had a low idle for them to work on. They said it was throwing a speed sensor code so they replaced I believe two of them and did the fluid. Results: Now my transmission wont shift when in drive to a higher gear and my speedometer doesn’t work. They fixed the low idle by cleaning the throttle body. I also have had trouble when hitting bumps, it says to “service brake system, and the door locked cycle and the abs and brake light come on. The shifting problem really has me worried now. IT has 140,000 miles on it. I had the cluster replaced about 2 years ago. Could the new speed sensor be causing this? Other thought? I sure appreciate it. Thanks!
Since you mentioned a speed sensor code, was the ABS, Brake or Traction Controls lights on at anytime? If yes, check the brake fluid level in the master cylinder reservoir. To be of much more help I would need code numbers.