"Reduced engine power"

[kayakfish247]

hey guys. So I'm new here. I have a 2003 with a 5.3 Vin z. It's probably thw best running engine I've ever owned. But is has the dreaded p1516 p0120 p0220 which are all with the tac module throttle body and throttle pedal position. I've replace the tac, throttle body, tps on the pedal, cleaned the intake temp sensor replace the mass air sensor, and ran a ground wire from the throttle body to the ecm to tac and to the engine then to the body. Also cleaned the ground junctions at the lower driver's side body and behind the head. It still throws intermittent faults listed above while driving and goes into reduced engine power. I leave a scanner connected and clear the fault and it goes back to normal. Seems to do it alot more when it rains and it's cold outside. Lately it's been doing it at highway speeds. More often when idling. Anyone got any ideas? Pretty much only thing left is an engine harness which I believe is the issue. Thanks ahead of time.

 

[Scottydoggs]

have you replaced the pig tail pugs to everything tb related? they go bad.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum, and other members will chime in.

 

[kayakfish247]

have you replaced the pig tail pugs to everything tb related? they go bad.

Hey thanks for the reply. No but I did re-pin the connectors on the throttle body and the tac module but like I said I believe it has a wire breaking down.

 

[strutaeng]

Find a wiring diagram and back probe the pins at the ECU and run temporary wires to the TAC/throttle body. See if that makes any difference.

You will basically have another set of wires in parallel, so if there's issue on the main harness, the temporary wires will prevent the intermittent loss of signal triggering the code.

If the problem goes away, then you know where the problem lies.

 

[Fless]

Hey thanks for the reply. No but I did re-pin the connectors on the throttle body and the tac module but like I said I believe it has a wire breaking down.

As @ScottyBoy noted, the wires to (especially) the throttle body are prone to breaking underneath the insulation. If a careful inspection hasn't been done, suggest doing it from the TB back about a foot. You may not see a broken wire, so check them by flexing and by feel. A new pigtail might solve it. I think it was @89Suburban who cured his this way.

 

[kayakfish247]

Find a wiring diagram and back probe the pins at the ECU and run temporary wires to the TAC/throttle body. See if that makes any difference.

You will basically have another set of wires in parallel, so if there's issue on the main harness, the temporary wires will prevent the intermittent loss of signal triggering the code.

If the problem goes away, then you know where the problem lies.

That actually sounds like a good idea. Definitely try that. I actually have terminals I can use to run a new temp harness. Thanks

 

[89Suburban]

Thanks @Fless yeah my pigtail had been replaced by somebody and the connections took a crap so I re-soldered them and she has been fine since. Some pics here. Was a ***** to figure out I almost said hell with it and got rid of her.

What did you do to your NNBS GMT900 Tahoe/Yukon Today?

Just got done swapping both upstream O2 sensors. No codes, just 162k on the originals and I know older O2 sensors get 'lazy' and tend to not meter as well. Started her up and it seemed to idle a little smoother. We'll see if I get better drivability or more MPGs. Driver side was the one that is...

www.tahoeyukonforum.com

 

[rockola1971]

Very common failure after the dreaded dead spot in the TPS position trace within the TPS. Then comes the Pigtail plugged into the TPS (They make a replacement that you just splice in) and then finally the harness that plugs into the the TAC Module itself. All 3 of these will cause the dreaded reduced engine power individually or collectively.

 

[kayakfish247]

That actually sounds like a good idea. Definitely try that. I actually have terminals I can use to run a new temp harness. Thanks

Afternoon. So I dug into this and removed the ground (black with white) off the pass side block. Re-grounded it to a good know ground but in the beginning I noticed when turning the key on the butterfly in the throttle body is fluttering and making a rattling noise with the engine off and also with the engine idling it make the same noise. Never noticed that before. I'm wondering if the actuator of the throttle body is faulty. Like I said it was a new throttle body replaced in August of 23. Anyone have an idea?

 

[chadfranks]

Afternoon. So I dug into this and removed the ground (black with white) off the pass side block. Re-grounded it to a good know ground but in the beginning I noticed when turning the key on the butterfly in the throttle body is fluttering and making a rattling noise with the engine off and also with the engine idling it make the same noise. Never noticed that before. I'm wondering if the actuator of the throttle body is faulty. Like I said it was a new throttle body replaced in August of 23. Anyone have an idea?

I am in the exact place you are, have you figured anything out? With the fluttering I suspected either ECM, or TAM, Or a ground, I've replaced both and ran new grounds as others have to the ecm, to the back of the engine, everywhere, I have ohmed out the wires from the TAM to the pigtail to the throttle body and shook the wires and harness while ohmed out and saw no issues, in the wiring but I still want to change the wiring harness because it is the only thing I can see, Unless the alternator is causing noise, or the battery negative isn't actually connected anymore in the molded connector, it has a new throttle body, on my diagnostics, when it throws the code, the ecm really isn't seeing any voltage on the wires from the sensor and the fluttering means there's some type of connection issue, it has no problem reporting the voltage from the gas pedal so ecm to tac connections should be fine, the only thing I can think is to change the wiring harness which I did get caught under the intake on this fix when I changed fuel injectors and plugs and wires. GM Parts Giant doesn't show the harness part number because is is discontinued so I'm not 100% where to buy one from, amazon review on a $75 one showed they had to repin some of the purple connector on the ecm, let me know what you got going

 

[89Suburban]

I am in the exact place you are, have you figured anything out? With the fluttering I suspected either ECM, or TAM, Or a ground, I've replaced both and ran new grounds as others have to the ecm, to the back of the engine, everywhere, I have ohmed out the wires from the TAM to the pigtail to the throttle body and shook the wires and harness while ohmed out and saw no issues, in the wiring but I still want to change the wiring harness because it is the only thing I can see, Unless the alternator is causing noise, or the battery negative isn't actually connected anymore in the molded connector, it has a new throttle body, on my diagnostics, when it throws the code, the ecm really isn't seeing any voltage on the wires from the sensor and the fluttering means there's some type of connection issue, it has no problem reporting the voltage from the gas pedal so ecm to tac connections should be fine, the only thing I can think is to change the wiring harness which I did get caught under the intake on this fix when I changed fuel injectors and plugs and wires. GM Parts Giant doesn't show the harness part number because is is discontinued so I'm not 100% where to buy one from, amazon review on a $75 one showed they had to repin some of the purple connector on the ecm, let me know what you got going

@915_Tahoe is there a part number for the mentioned harness sir?

 

[rockola1971]

@915_Tahoe is there a part number for the mentioned harness sir?

Its under electrical-connector on rockauto "Throttle Position Sensor (TPS) Connector". I looked up for a 2006. https://www.rockauto.com/en/catalog...throttle+position+sensor+(tps)+connector,2624

 

[chadfranks]

@915_Tahoe is there a part number for the mentioned harness sir?

I used this pigtail from Amazon, it does have color coded wires where the rock auto one shows all white, regardless it did not fix my p1516 reduced engine power, I thought it did at first but it came back, so I must have another break somewhere

 

[89Suburban]

I was referring to a complete harness not just the pigtail.

 

[kayakfish247]

I am in the exact place you are, have you figured anything out? With the fluttering I suspected either ECM, or TAM, Or a ground, I've replaced both and ran new grounds as others have to the ecm, to the back of the engine, everywhere, I have ohmed out the wires from the TAM to the pigtail to the throttle body and shook the wires and harness while ohmed out and saw no issues, in the wiring but I still want to change the wiring harness because it is the only thing I can see, Unless the alternator is causing noise, or the battery negative isn't actually connected anymore in the molded connector, it has a new throttle body, on my diagnostics, when it throws the code, the ecm really isn't seeing any voltage on the wires from the sensor and the fluttering means there's some type of connection issue, it has no problem reporting the voltage from the gas pedal so ecm to tac connections should be fine, the only thing I can think is to change the wiring harness which I did get caught under the intake on this fix when I changed fuel injectors and plugs and wires. GM Parts Giant doesn't show the harness part number because is is discontinued so I'm not 100% where to buy one from, amazon review on a $75 one showed they had to repin some of the purple connector on the ecm, let me know what you got going

Actually. I replaced the tps on the "new" throttle body I just got less than a year ago and I replaced the pigtail to the throttle body and so far it's all good. There's a kit from advance that has both. I think it's a Dorman kit. I do know the tac modules do cause alot of issues also every time you replace something dealing with the fuel throttle position there's a re-learn process. Look it up on you tube. Good luck. Hope this helps. Let me know if I can be anymore help.

 

[chadfranks]

I was referring to a complete harness not just the pigtail.

The whole harness that I ordered was

4L60E DBW DAC095, now it has the ECM connectors as Blue and Green, I think that is the biggest difference to look our for, My Tahoe is a LT 5.3L Flex fuel, but when I first suspected the ECM, I thought I'd just swap with my truck and that wasn't possible, it's keyed connectors to the ECM are Red and Blue​

That is the biggest difference to figure out red and blue or blue and green, now Amazon will tell you if it fits your vehicle but that's not 100% but at least will prevent ordering the wrong one most of the time

 

[915_Tahoe]

@915_Tahoe is there a part number for the mentioned harness sir?

I would need the VIN#

 

[chadfranks]

I would need the VIN#

Hey, I think I finally have mine fixed, my events were had an unrelated issue involved disconnecting the Throttle connectors, an issue was created or uncovered there. When suspecting bad sensor in the Throttle body, replaced the throttle body, it would flutter when key went into second position, like it could not control the throttle body or needed to retune, after seeing there was no voltage back from sensor, I knew I had a connector problem, fixed that but still had an issue, I fixed grounds, swapped computer, swapped tbc module, those did not fix so I returned. Ultimately decided to put the original throttle back on because I had fixed the connector and saw that the original unit was fine, i just had a problem in that pigtail

 

[kayakfish247]

Hey, I think I finally have mine fixed, my events were had an unrelated issue involved disconnecting the Throttle connectors, an issue was created or uncovered there. When suspecting bad sensor in the Throttle body, replaced the throttle body, it would flutter when key went into second position, like it could not control the throttle body or needed to retune, after seeing there was no voltage back from sensor, I knew I had a connector problem, fixed that but still had an issue, I fixed grounds, swapped computer, swapped tbc module, those did not fix so I returned. Ultimately decided to put the original throttle back on because I had fixed the connector and saw that the original unit was fine, i just had a problem in that pigtail

Good deal. Yeah mine is still all good.