Reduced Engine power, Check Engine.. and other errors...

[408sjtahoe]

got the call yesterday from the mechanic and it ended up being the gas pedal sensor, so the whole pedal must be replaced. $297 total, its not bad but i do hope this is the fix as I've heard others fix this and other parts related to this issue and still get that error message.

 

[Maximus1]

got the call yesterday from the mechanic and it ended up being the gas pedal sensor, so the whole pedal must be replaced. $297 total, its not bad but i do hope this is the fix as I've heard others fix this and other parts related to this issue and still get that error message.

I really hope that fixes your problem, but I'm a mechanic for 20 years and thought the same thing when I kept getting the reduced engine power code. The pedal sensor fixed my problem for a little while then came right back.

I took it to the dealership and come to find out my cranking issue was because one of the ground wires on the back of the engine didn't get connected back when I cleaned them and that's why it wouldn't start.

After speaking with the mechanic at the dealership he said that everytime one of these Tahoe's (2000-2007) comes in with the reduced engine power code is always linked to a bad ground issue. He told me that even if you remove and clean them that they still may not get a good ground. GM knows about this problem but refuse to issue a recall. What he did with mine and all the others that come in is this.

On the main harness running from the fuse box to the engine, find the black wire with a white stripe. Cut this wire and splice it adding a extra wire on one end and then run it directly to the negative side of the battery. This is what he did to mine and all I can say is WOW! That has not only fixed my reduced engine power problem but now the throttle is a lot more responsive and quicker to react. I wouldn't normally condone cutting any wires on a main harness to an engine but this really helped out. It not only boosts the ground to the back of the engine but also to the fuse box and TAC module. I hope that this information will help anyone who finds themselves in the same situation as I was. After replacing nearly every piece related to my throttle body including the harness from the pedal to the TAC module it all came down to a known grounding issue that cost me literally a couple bucks for some wire and a splice kit. My headache that I've had for the last 7 days is gone. Good luck

 

[Zeke]

I'm in the same boat. 2004 Tahoe 5.3 Flex fuel. Replaced grounds, replace TAC module, cleaned throttle body, replaced both the TPS sensor and pedal sensors twice. I STILL HAVE the reduced engine power. Codes U0107 P1526 and a third that I can't remember also today my ABS light came on. I'm going to replace the whole throttle body next and if that doesn't work then I'm replacing the ECM unless someone else has a better idea.

I

 

[Maximus1]

One other note is to have your alternator tested not just to see if it's charging but also have the voltage regulator tested that is built into the alternator. Mine passed the charging test but failed the regulator test. I was having wild voltage swings from 12.0 all the way to 18.6. This caused all kinds of electrical problems including blowing fuses which made me think something else was wrong. This is my third alternator in less than a year. Luckily I bought the lifetime warranty alternator so it's replaced for free. These aftermarket alternators are junk. I believe if this one goes out I'm going to return this one and get my money back and then go to the GM dealership and buy the OEM alternator. The original alternator (AC Delco) lasted over 11 years. These duralast ones are made in China and they can't seem to make one with a good regulator.

 

[uscjfs2012]

I really hope that fixes your problem, but I'm a mechanic for 20 years and thought the same thing when I kept getting the reduced engine power code. The pedal sensor fixed my problem for a little while then came right back.

I took it to the dealership and come to find out my cranking issue was because one of the ground wires on the back of the engine didn't get connected back when I cleaned them and that's why it wouldn't start.

After speaking with the mechanic at the dealership he said that everytime one of these Tahoe's (2000-2007) comes in with the reduced engine power code is always linked to a bad ground issue. He told me that even if you remove and clean them that they still may not get a good ground. GM knows about this problem but refuse to issue a recall. What he did with mine and all the others that come in is this.

On the main harness running from the fuse box to the engine, find the black wire with a white stripe. Cut this wire and splice it adding a extra wire on one end and then run it directly to the negative side of the battery. This is what he did to mine and all I can say is WOW! That has not only fixed my reduced engine power problem but now the throttle is a lot more responsive and quicker to react. I wouldn't normally condone cutting any wires on a main harness to an engine but this really helped out. It not only boosts the ground to the back of the engine but also to the fuse box and TAC module. I hope that this information will help anyone who finds themselves in the same situation as I was. After replacing nearly every piece related to my throttle body including the harness from the pedal to the TAC module it all came down to a known grounding issue that cost me literally a couple bucks for some wire and a splice kit. My headache that I've had for the last 7 days is gone. Good luck

I really hope that fixes your problem, but I'm a mechanic for 20 years and thought the same thing when I kept getting the reduced engine power code. The pedal sensor fixed my problem for a little while then came right back.

I took it to the dealership and come to find out my cranking issue was because one of the ground wires on the back of the engine didn't get connected back when I cleaned them and that's why it wouldn't start.

After speaking with the mechanic at the dealership he said that everytime one of these Tahoe's (2000-2007) comes in with the reduced engine power code is always linked to a bad ground issue. He told me that even if you remove and clean them that they still may not get a good ground. GM knows about this problem but refuse to issue a recall. What he did with mine and all the others that come in is this.

On the main harness running from the fuse box to the engine, find the black wire with a white stripe. Cut this wire and splice it adding a extra wire on one end and then run it directly to the negative side of the battery. This is what he did to mine and all I can say is WOW! That has not only fixed my reduced engine power problem but now the throttle is a lot more responsive and quicker to react. I wouldn't normally condone cutting any wires on a main harness to an engine but this really helped out. It not only boosts the ground to the back of the engine but also to the fuse box and TAC module. I hope that this information will help anyone who finds themselves in the same situation as I was. After replacing nearly every piece related to my throttle body including the harness from the pedal to the TAC module it all came down to a known grounding issue that cost me literally a couple bucks for some wire and a splice kit. My headache that I've had for the last 7 days is gone. Good luck

Can you tell me or show me which black wire with white atripe you are talking about? My 2003 tahoe has several small black wires with white strips running from fuse box to engine.

 

[reath1]

For anyone else that runs into this issue, I highly recommend following Maximus1's advice. I, too, know my way around under a vehicle. I fought the P1516 and P1518 for 3 days. First, removing the ground from the right rear of the block extending it to a firewall stud. Checked ground continuity. 1.6 ohms. I thought that that was a good ground. It would easily light a test light. Still had the codes. I then changed the TBS, TBS harness, TAC module, APS and finally the TB. All to no avail. At that point I used Maximus1 advice above. Opened the harness right off of the underhood fuse block. About 12 inches from the fuse block you'll find a factory splice of 3 blacks w/ white stripes going into one. Jump off right there with a new ground going straight to block. I went to one of the lower bolts on the alternator bracket. One holds two grounds already. I went to the other one. Ohm'd that new ground at 0.00. Cleared the codes and cranked it up. No codes.

 

[00chevyHd]

mine has voltage problems i looked at some videos and found out if i move this ground point to the firewall would it be okay if i take the risk heres a pic of the bolt on back of the engine block help please

 

[IrishScout76]

What ended up working for you? I’m in the same boat now. I’ve replaced the TAC, MAF, cleaned the throttle body, APP, and added cold air intake. Still in limp mode and throws a p1125. I’ve checked the harness…wires and pins look fine. I’m about to set the damn thing on fire in my driveway!!

 

[tomloans]

For anyone else that runs into this issue, I highly recommend following Maximus1's advice. I, too, know my way around under a vehicle. I fought the P1516 and P1518 for 3 days. First, removing the ground from the right rear of the block extending it to a firewall stud. Checked ground continuity. 1.6 ohms. I thought that that was a good ground. It would easily light a test light. Still had the codes. I then changed the TBS, TBS harness, TAC module, APS and finally the TB. All to no avail. At that point I used Maximus1 advice above. Opened the harness right off of the underhood fuse block. About 12 inches from the fuse block you'll find a factory splice of 3 blacks w/ white stripes going into one. Jump off right there with a new ground going straight to block. I went to one of the lower bolts on the alternator bracket. One holds two grounds already. I went to the other one. Ohm'd that new ground at 0.00. Cleared the codes and cranked it up. No codes.

This is an old thread but curious if anyone can point out which wire was grounded. See below what I found and please confirm for me. Thank you!