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.
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1.The MAF does not have to be replaced. You will have to take the intake tube between the MAF and the throttle body off.
2.The tps is built into the throttle body and is not replaceable. I am assuming that you have confirmed that you have an electronic throttle body on your vehicle.
3. A cleaned old throttle body or a new throttle body will produce a higher than desired idle. The reason is that the PCM has learned the amount of carbon build up over the course of months or years. Now that the carbon is gone more air will come into the engine. To relearn on these vehicles all you have to do is disconnect battery power from the PCM. With a clean throttle body and learned memory erased the idle will return to normal. If you disconnect the battery to clear the PCM memory, remember that the a/c system will also perform a system recalibration. I would suggest reading more about that. You can find a “Recalibration” link on the left hand side bar.
Sparky, I just stumbled upon this article, and I have this exact vehicle, exact same problem. I have an 03 Tahoe, 5.3, z-flex. Getting code p1516 (nothing else), battery is good. I am going to start by cleaning the throttle body. I am sure I’ll have to replace it, but I have a few questions. 1. Do I have to replace the MAF? 2. Is this drive by wire, in that the TPS is part of the throttle body, and can’t be replaced by itself. 3. (biggest?) Do I have to do a Idle Relearn after replacing the TB? The dealership is saying, yes ($101) + $86 to diagnose, and another $400 to replace TB. They’ve lost their minds. Thanks for the help, hopefully this thread isn’t too old. Great work, by the way!
The P2135 code is for a problem with the TPS signal from the throttle body assembly to the TAC or PCM depending on the year. My diagnostic procedure is to look at data while gently wiggling the the throttle body wiring , one wire at a time. In particular the yellow wire. If nothing shows, I replace the throttle body assembly and advise the customer. Replacing the throttle body in most cases will fix the problem and is not invasive to the wiring harness. To solder or not to solder is a subjective question. There are pluses and minuses to both types of repairs. I prefer to not solder when there is a vibration issue as is commonly found on an engine. Soldering changes a multistrand flexible wire into a single strand rigid wire that is prone to fracturing. The crimp terminals that come with the repair harness are good if used properly. Staggering the splices, proper crimping tool, applying heat to shrink the insulation and taping the harness back up. I prefer using high quality uninsulated splicing terminals and heat shrink tubing with a sealer built in, as it makes for a less bulky repair.
My 2005 Z-71 Tahoe is having the same reduced power issues as listed above. I am getting the code of P-2135 and after reading up on it I replaced the wiring harness/plug going into the throttle body. It didn’t fix the issue so I paid the dealership to run the diagnostic and they told me they would have done the same thing but that I will have to solder the wires and not use the bitt splice that came with the AC Delco part. Then if that didn’t work they would replace the throttle body. With the P-2135 code for the pedal sensor should i have started with the wiring? Would the soldering make that big of a difference? Would the next step be the throttle body replacement, as I know it is super clean? Thank you!
It could be as low as $150 if you do it yourself. As high as $600 if you pay a shop. At my shop I would charge a total of $370 parts, labor and tax. There would however be an additional charge if one needed me to diagnose the problem and guarantee the repair.