2002 silverado TAC

[Movieguymookum]

This problem is getting more and more vexxing.

I have a 2002 Silverado 1500, 5.3L V8. Door tag says is was made 3/02.

My problem is low speed idle w/ aircon on, mainly. The truck is shutting off because it is idling way to low when I turn anywhere, like a parking spot, and don't keep my foor on the pedal. Sitting at a light or stop with aircon on the truck lopes and the tach surges and drops from 600/700 down to 200/300 and even dying if I am turning the wheel without foot on pedal.

Everyone I have talked to at the parts houses here and a few mechanic friends say the same thing. Idle Air Control Valve.

That is all good, but this engine does not have one. It has the TAC, Throttle Actuator Control on the (looking from the front of the engine) left side of the throttle body. The TPS is on the right. There are no other sensors on this throttle body.

In that is the problem, no one lists this TAC as even available for an 02. AutoZone, O'Reilly's and Advanced cannot look this part up.

Can someone tell me how to get this part or maybe a part number? Is it dealer only? Looking on the intertubez the only year models I find associated with a TAC is 03 and up.

Any help would be appreciated.

[someday31]

Originally Posted by Movieguymookum

This problem is getting more and more vexxing.

I have a 2002 Silverado 1500, 5.3L V8. Door tag says is was made 3/02.

My problem is low speed idle w/ aircon on, mainly. The truck is shutting off because it is idling way to low when I turn anywhere, like a parking spot, and don't keep my foor on the pedal. Sitting at a light or stop with aircon on the truck lopes and the tach surges and drops from 600/700 down to 200/300 and even dying if I am turning the wheel without foot on pedal.

Everyone I have talked to at the parts houses here and a few mechanic friends say the same thing. Idle Air Control Valve.

That is all good, but this engine does not have one. It has the TAC, Throttle Actuator Control on the (looking from the front of the engine) left side of the throttle body. The TPS is on the right. There are no other sensors on this throttle body.

In that is the problem, no one lists this TAC as even available for an 02. AutoZone, O'Reilly's and Advanced cannot look this part up.

Can someone tell me how to get this part or maybe a part number? Is it dealer only? Looking on the intertubez the only year models I find associated with a TAC is 03 and up.

Any help would be appreciated.

You are right the 5.3s dont have them, only the 4.3 do. I would try cleaning the mass air flow sensor with maf cleaner and also cleaning the throttle body and see what that does....any check engine lights??

[Movieguymookum]

5.3 does have them, at least the 99 and 00 do, not sure about the 01. Had the luck that a parts manager and a store manager had one and the other in the parking lot when I went to AutoZone. It seems what Haynes refers to as "early" v8's with the throttle body that had wires to manually operate the butterfly did have IAC and were located neatly by the TPS. Sometime in 02 though, Chevrolet found it wise to combine a myriad of sensors and controllers into this neat little plastic tube to take care of traction control, cruise control, IAC funtions, etc. My problem is, no one can look up that part, the computers just don't have it.


Just had the codes checked even though there was no SES light on the off chance there was one. No codes.

[someday31]

Originally Posted by Movieguymookum

5.3 does have them, at least the 99 and 00 do, not sure about the 01. Had the luck that a parts manager and a store manager had one and the other in the parking lot when I went to AutoZone. It seems what Haynes refers to as "early" v8's with the throttle body that had wires to manually operate the butterfly did have IAC and were located neatly by the TPS. Sometime in 02 though, Chevrolet found it wise to combine a myriad of sensors and controllers into this neat little plastic tube to take care of traction control, cruise control, IAC funtions, etc. My problem is, no one can look up that part, the computers just don't have it.


Just had the codes checked even though there was no SES light on the off chance there was one. No codes.

I found ones on ebay....

[Movieguymookum]

This is not a part I want to buy used.

[j cAT]

Originally Posted by Movieguymookum

This is not a part I want to buy used.

you will need to purchase a new throttle body with a drive by wire/no cable to the throttlebody gas pedal. this TAC is not replaceable separate from the throttle body. the 2000 5.3L engine is however replacable. I doubt this is a solution to your problem ..TAC failres result in low power mode..this means your speed will be limited to 20 MPH.

also you will get the failure code indicating this...did you get any failure codes pulled ??? that is a good start ..

[j cAT]

Originally Posted by Movieguymookum

This problem is getting more and more vexxing.

I have a 2002 Silverado 1500, 5.3L V8. Door tag says is was made 3/02.

My problem is low speed idle w/ aircon on, mainly. The truck is shutting off because it is idling way to low when I turn anywhere, like a parking spot, and don't keep my foor on the pedal. Sitting at a light or stop with aircon on the truck lopes and the tach surges and drops from 600/700 down to 200/300 and even dying if I am turning the wheel without foot on pedal.

Everyone I have talked to at the parts houses here and a few mechanic friends say the same thing. Idle Air Control Valve.

That is all good, but this engine does not have one. It has the TAC, Throttle Actuator Control on the (looking from the front of the engine) left side of the throttle body. The TPS is on the right. There are no other sensors on this throttle body.

In that is the problem, no one lists this TAC as even available for an 02. AutoZone, O'Reilly's and Advanced cannot look this part up.

Can someone tell me how to get this part or maybe a part number? Is it dealer only? Looking on the intertubez the only year models I find associated with a TAC is 03 and up.

Any help would be appreciated.

idle problems are in most cases result from PCV /hoses defective or the IAC/throttlebody carboned up...

when was the last time you cleaned the throttlebody IAC ?

this is usually done every 20-30,ooomi to avoid these issues...

using throttlebody cleaner remove the IAC and with a tooth brush and the cleaner carefully clean the valve...with the rubber air duct removed clean the thottlebody..when it looks good, use a hair dryer to evap any excess cleaner..keep the throttle plate open for 15 minutes to allow evaporation of the cleaning product ...then put back together and start..

do not force the IAC valve /try to make the valve move as this will break it..

IAC function is when the idle drops the PCM/computer tells the IAC to open and allow more air into the engine, the the pcm can now allow injectors to turn on for a longer time to increase idle and keep the air/fuel mixtures correct..if this valve is stuck by carbon or the passageway plugged by this crap you will have what YOU got NOW !


with the PCV system leaks the idle will be too high which is another common issue ...

DO NOT USE CARB CLEANER ON THIS ENGINE !

[Movieguymookum]

Originally Posted by j cAT

using throttlebody cleaner remove the IAC

Okay, this is the crux of my problem. Where is the IAC located on a 2002 5.3 with a TAC?

[j cAT]

Originally Posted by Movieguymookum

Okay, this is the crux of my problem. Where is the IAC located on a 2002 5.3 with a TAC?

I thought your 2002 had the IAC., if this has the drive by wire TAC then this IAC is not used ...the problem with the idle however is repaired when you clean the throttle body and those small holes in it near the throttle plate..using the throttlebody cleaner and a tooth brush to work out the carbon deposits ..
remove the air duct from the engine /intake.do not use too much throttlebody cleaner ..allow to dry before starting,,,,. just to be safe remove the battery negative terminal...when working it ..

[777stickman]

One thing I've seen over the Chevy years is that the door sticker date is not the same as the VIN year model. Sure it says it was built in '02 but it may be VIN'd as an '03.

Case in point: My Chevy Sub has a build date on the door sticker as 03/1998 but it's VIN'd as a 1999?? When I get parts for it at the dealer or on-line I always give the VIN. At a parts store I ask them to check both '98 & '99 to see if there is any difference. If there is I mostly go with the '99.

Hope this helps in the future.

[Movieguymookum]

B-12 ChemTool, about 4 bucks, and an old toothbrush and some paper towels. There was an amazing amount of buildup just behind the blade and in the ports in the throat. 30 mins of scrubbing and a good hour to be safe it was dry and it was like night and day on idling. Now I can sit at idle with the aircon on and it actually cool and turn into a parking spot without the truck going dead.

Thanks for those with useful information.

[j cAT]

Originally Posted by Movieguymookum

B-12 ChemTool, about 4 bucks, and an old toothbrush and some paper towels. There was an amazing amount of buildup just behind the blade and in the ports in the throat. 30 mins of scrubbing and a good hour to be safe it was dry and it was like night and day on idling. Now I can sit at idle with the aircon on and it actually cool and turn into a parking spot without the truck going dead.

Thanks for those with useful information.

thats alot cheaper than a new throttlebody/TAC !

this is needed like I stated every 30-40,ooomi...then you will have no problems...just use the correct safe cleaning products..good luck..