2003 Reduced Engine Power in Tahoe; Only code 1516 now

[Xirius]

Lots of good advice here, but I'll take any other ideas! Here is what I've done:

1) Replaced all grounds plus added ground strap directly to TAC
2) Replaced pedal sensor
3) Replaced pedal harness
4) Replaced TAC
5) Ran new wiring from TAC to Throttle Body (replacing the plug on TB)
6) Replaced Throttle Body
7) Replaced negative battery cable
8) Did relearn on the pedal and the idle
9) New battery

When I started this, I got some 120 and 220 codes, but now I am down to the dreaded 1516. And, of course, the even more dreaded Reduced Engine Power. This DOES NOT happen when the car is in Cruise Control. It has always seemed to be an issue when taking my foot off the pedal to accelerate. I cannot recall it happening when going uphill or accelerating.

The only component not replaced is the ECM. There was some sort of 'recall' back in 2005 or 06, but while we always had gremlins, they did not cause the car to stop in traffic. Would reflashing or replacing be recommended? There are other oddities, such as the seat controls reversing ( push forward / seat goes backward) and the Anti-theft went crazy Way after Reduced Engine came about. So I did the bypass on the Anti-theft.


I understand that the popular notion is that this is a ground problem. BUT...why does the vehicle drive fine while on Cruise Control?

2003 Tahoe 5.3L

 

[rockola1971]

Did you replace the TPS itself? How about the wiring harness plug itself at the TAC module? Its not uncommon for the wiring right as it enters the plug body to break there.

 

[tomloans]

Hopefully you replaced all sensors with OEM. ACDelco for the throttle body for sure. When you replaced the pigtail and if that was the problem, it is imperative that you solder the connections. Super important! Also as you do this, be careful with the 8 wires at the TPS, you could actually break another as you are handling the wiring. I did everything you did plus more and the reality was that my wiring job was bad. Once I reconnected the wiring with direct soldering, all was well again...

 

[Eldiablo]

Lots of good advice here, but I'll take any other ideas! Here is what I've done:

1) Replaced all grounds plus added ground strap directly to TAC
2) Replaced pedal sensor
3) Replaced pedal harness
4) Replaced TAC
5) Ran new wiring from TAC to Throttle Body (replacing the plug on TB)
6) Replaced Throttle Body
7) Replaced negative battery cable
8) Did relearn on the pedal and the idle
9) New battery

When I started this, I got some 120 and 220 codes, but now I am down to the dreaded 1516. And, of course, the even more dreaded Reduced Engine Power. This DOES NOT happen when the car is in Cruise Control. It has always seemed to be an issue when taking my foot off the pedal to accelerate. I cannot recall it happening when going uphill or accelerating.

The only component not replaced is the ECM. There was some sort of 'recall' back in 2005 or 06, but while we always had gremlins, they did not cause the car to stop in traffic. Would reflashing or replacing be recommended? There are other oddities, such as the seat controls reversing ( push forward / seat goes backward) and the Anti-theft went crazy Way after Reduced Engine came about. So I did the bypass on the Anti-theft.


I understand that the popular notion is that this is a ground problem. BUT...why does the vehicle drive fine while on Cruise Control?

2003 Tahoe 5.3L

Hey bud just for ***** n giggles. Pull the cover off your fuse box, and check the three power leads coming into box that are bolted down. See if you have 12 volts on the center one?

 

[rockola1971]

Check your ground wires in the A pillar?

 

[stretchit]

Lots of good advice here, but I'll take any other ideas! Here is what I've done:

1) Replaced all grounds plus added ground strap directly to TAC
2) Replaced pedal sensor
3) Replaced pedal harness
4) Replaced TAC
5) Ran new wiring from TAC to Throttle Body (replacing the plug on TB)
6) Replaced Throttle Body
7) Replaced negative battery cable
8) Did relearn on the pedal and the idle
9) New battery

When I started this, I got some 120 and 220 codes, but now I am down to the dreaded 1516. And, of course, the even more dreaded Reduced Engine Power. This DOES NOT happen when the car is in Cruise Control. It has always seemed to be an issue when taking my foot off the pedal to accelerate. I cannot recall it happening when going uphill or accelerating.

The only component not replaced is the ECM. There was some sort of 'recall' back in 2005 or 06, but while we always had gremlins, they did not cause the car to stop in traffic. Would reflashing or replacing be recommended? There are other oddities, such as the seat controls reversing ( push forward / seat goes backward) and the Anti-theft went crazy Way after Reduced Engine came about. So I did the bypass on the Anti-theft.


I understand that the popular notion is that this is a ground problem. BUT...why does the vehicle drive fine while on Cruise Control?

2003 Tahoe 5.3L

Im in the same boat right now. I am down to two more solutions to try. I read that the PCM or ECU could be stuck in limp mode. Changing it might help. Also any wires you crimped and used a heat shrink on might add to the problem. Read that if you solder the wires one at a time and make sure they are fully connected it might help fix the issue. Not sure if you found solution.