DREADED: "Reduced Engine Power"

douart · September 13, 2014

2003 Silverado 1500 HD
DTC P1516

I have:

1 Googled several days and read many posts.
2 cleaned the Throttle Body
3 checked connections for soundness and broken wires
4 checked power, ground, resistance, and signal of TB sensors 1 & 2 and motor
5 checked power, ground, resistance, and signal of APP unit
(I used digital and analog multimeters to check values and responses)

One thread I was following about a 2003 Silverado 2500 stated more than once that the "TAC module" was part of the Throttle Body and there was not a separate "TAC module". Perhaps that was not a HD series.
This truck has a separate "TAC module".

I have not yet found any information concerning "Testing Diagnosing or Troubleshooting" this "TAC module".

Can anyone help me?

Thanks Don,

02suburbanZ71 · September 13, 2014

Did you delete the code and see if it came back

gmtech4 · September 13, 2014

you buy service information from alldata.com ,then you follow the diag table ,,,,,

if you dont have a scanner ,,,,your finished before you start ,,,,,,,

take it in ,you'll make yourself nuts trying to do this

douart · September 14, 2014

02suburbanZ71

Yes, I have a scanner.

I have cleared the code (P1516) three times.

The first time the ignition was locked and the truck would not restart until i cleared the code.

The other times that the truck went into reduced power mode it would restart.

I was not driving those times. I was called to retrieve and start the truck.

After that was when I started researching and testing about the problem.

The first occurrence was maybe a month before the latter two. The latter two happened about two days apart.

After doing the work that I listed in my first post the owner of the truck and I traded vehicles. I drove the truck for about ten days with the scanner attached trying to catch the error with a DTC trigger, but I had no problems or codes.

We traded vehicles back and i left my scanner with the owner so he would not be stranded if (when) the truck went into reduced power again.

I have no reason to believe that it will not happen again and, of course, due to the danger presented of it happening at some situations I would like find and fix the problem.

govtech4

I have not used alldata before. Will they have any more information than I have already found? I would like to know how to "Test Diagnose or Troubleshoot" the "TAC module".

If I knew they had that information I would be interested,

Thanks for the interest,

Don

02suburbanZ71 · September 14, 2014

02suburbanZ71

Yes, I have a scanner.

I have cleared the code (P1516) three times.

The first time the ignition was locked and the truck would not restart until i cleared the code.

The other times that the truck went into reduced power mode it would restart.

I was not driving those times. I was called to retrieve and start the truck.

After that was when I started researching and testing about the problem.

The first occurrence was maybe a month before the latter two. The latter two happened about two days apart.

After doing the work that I listed in my first post the owner of the truck and I traded vehicles. I drove the truck for about ten days with the scanner attached trying to catch the error with a DTC trigger, but I had no problems or codes.

We traded vehicles back and i left my scanner with the owner so he would not be stranded if (when) the truck went into reduced power again.

I have no reason to believe that it will not happen again and, of course, due to the danger presented of it happening at some situations I would like find and fix the problem.

govtech4

I have not used alldata before. Will they have any more information than I have already found? I would like to know how to "Test Diagnose or Troubleshoot" the "TAC module".

If I knew they had that information I would be interested,

Thanks for the interest,

Don

I think its time to go back to the dealer

chupe442 · September 15, 2014

I have heard that this may be caused by the computer needing to be reflashed with current firmware or something to that effect.. My 03 2500 did this up until I traded it in. Spent alot of time chasing it down but heard of the flash after the fact... Good luck!

douart · September 15, 2014

I think its time to go back to the dealer

Thanks 02suburbanZ71,

If this truck was under warranty I would.

I do not have enough evidence or faith to believe that dealers can accurately diagnose this

problem.

I have heard that this may be caused by the computer needing to be reflashed with current firmware or something to that effect.. My 03 2500 did this up until I traded it in. Spent alot of time chasing it down but heard of the flash after the fact... Good luck!

Thanks chupe442

I am familiar with the reflash fix. I question whether a flash is needed for a problem that takes 11-12 years to show up, unless it is possible that data could become corrupted after this long.

I doubt that is the case.

I suspect the "TAC module". (DTC P1516)

Due to this problem can be extremely intermittent and can seemingly be fixed by replacing a part I want to test for faults before replacements.

I am looking for information about testing the "TAC module" sometimes called the "Throttle Control Unit (Module)".

The markings on the "TAC module" are:

TMD1-160A1 206-010609

Thanks Don

02suburbanZ71 · September 15, 2014

Thanks 02suburbanZ71,

If this truck was under warranty I would.

I do not have enough evidence or faith to believe that dealers can accurately diagnose this

problem.

Thanks chupe442

I am familiar with the reflash fix. I question whether a flash is needed for a problem that takes 11-12 years to show up, unless it is possible that data could become corrupted after this long.

I doubt that is the case.

I suspect the "TAC module". (DTC P1516)

Due to this problem can be extremely intermittent and can seemingly be fixed by replacing a part I want to test for faults before replacements.

I am looking for information about testing the "TAC module" sometimes called the "Throttle Control Unit (Module)".

The markings on the "TAC module" are:

TMD1-160A1 206-010609

Thanks Don

I feel the same about my vehicle. Sigh

gmtech4 · September 16, 2014

Alldata will have the code to follow , you need the experience and tooling to finish the diagnoses,,,,

How dare you say you have no faith in the dealer to fix it , sound a little arrogant to me , you are coming off a little to smug sir , have fun , you'll need it !! I'm out !!!! Lol

02suburbanZ71 · September 16, 2014

Alldata will have the code to follow , you need the experience and tooling to finish the diagnoses,,,,

How dare you say you have no faith in the dealer to fix it , sound a little arrogant to me , you are coming off a little to smug sir , have fun , you'll need it !! I'm out !!!! Lol

I don't mean to be. I just have taken it in for the slip yoke clunk, and rattling and they couldn't find the problem but i found out on here what the bad parts were [emoji16]

gmtech4 · September 16, 2014

I don't mean to be. I just have taken it in for the slip yoke clunk, and rattling and they couldn't find the problem but i found out on here what the bad parts were [emoji16]

not you ,the op

douart · September 17, 2014

Alldata will have the code to follow , you need the experience and tooling to finish the diagnoses,,,,

How dare you say you have no faith in the dealer to fix it , sound a little arrogant to me , you are coming off a little to smug sir , have fun , you'll need it !! I'm out !!!! Lol

Maybe the last part is tongue in cheek?

I take it that way anyway. How smug can I be, I am asking for help? Please !!!! Lol

Since i have not found the information i want I may give Alldata a go.

Thanks for your time.

jimmywes · September 17, 2014

I have had the same problem but I'm 75yrs. and can't afford to go to the dealer, however, I should have.

I replaced the throttle body with a rebuilt, then replaced it with a new one, replaced the accelerator apedal assy. (new) replaced the TAC module (new) New battery, New factor replacement plug and wires to throttle body actuator, soldered and shrink wrapped, cleaned mass air sensor. I have a GMC Sierra 1500 5.3old body style have a checker and still get U0107 (lost communications with throttle actuator control module.) I reset it and it runs good for about 5 min and goes into reduced engine power. Oh, I replace

the gas cap with a new factory one. Any ideas, would appreciate any help.

gmtech4 · September 18, 2014

I have had the same problem but I'm 75yrs. and can't afford to go to the dealer, however, I should have.I replaced the throttle body with a rebuilt, then replaced it with a new one, replaced the accelerator apedal assy. (new) replaced the TAC module (new) New battery, New factor replacement plug and wires to throttle body actuator, soldered and shrink wrapped, cleaned mass air sensor. I have a GMC Sierra 1500 5.3old body style have a checker and still get U0107 (lost communications with throttle actuator control module.) I reset it and it runs good for about 5 min and goes into reduced engine power. Oh, I replacethe gas cap with a new factory one. Any ideas, would appreciate any help.

Holy crap Jim , this is what happens when guessing bites a guy and hind site gets rather clear , unfortunately it happens to a lot of people