Throttle Body change pcm question

[fredhouse]

I'm changing my Throttle Body and my question is should i disconnect the battery or pull the pcm fuse when im done.I watched a video by MAY03LT but it was a I6 4.2.
I'm guessing its the same but want to be sure.THANK YOU FOR ALL YOUR HELP!

 

[xtitan1]

I'm changing my Throttle Body and my question is should i disconnect the battery or pull the pcm fuse when im done.I watched a video by MAY03LT but it was a I6 4.2.
I'm guessing its the same but want to be sure.THANK YOU FOR ALL YOUR HELP!

You're changing it or cleaning it? The idea is that your truck's PCM has changed its settings as your TB got dirty and now you need to reset it in order to get it to realize that the TB is clean again.

You do that by cutting power to the PCM. If you pull the PCM fuse, it will only cut the power to the PCM. If you pull the battery, it cuts power to everything in the truck.

Pulling the fuse will reset the PCM memory causing a relearn to hopefully take advantage of your now clean throttle body. By not disconnecting the battery, you avoid the negatives that come along with that, such as possibly killing your HVAC actuators.

Of course, some guys think that babying your actuators is a bad idea so they don't really consider this a negative because they figure it would be better to have them fail while you're working on the truck anyway rather then at a really bad time in the future.

I don't believe engine type makes a difference as far as this topic is concerned.

 

[fredhouse]

I am replacing the throttle body not cleaning it. The Throttle Position Sensor is bad but im assuming the pcm will need to be reset.

 

[chicagotransam]

I am replacing the throttle body not cleaning it. The Throttle Position Sensor is bad but im assuming the pcm will need to be reset.

So, you're replacing the whole throttle body for a bad TPS? Was that a difference between the LM4 and LH6?

 

[SSportWagon]

So, you're replacing the whole throttle body for a bad TPS? Was that a difference between the LM4 and LH6?

hello - I have a 2005 Envoy XUV with the 5.3l LH6 which has an intermitent P0121 code. My mechanic scanned it and said its a bad TPS sensor but that the TPS is not swappable - it needs a new TB.

If this is incorect, please advise.

When I search online, I have not been able to find anything directly related except that places like RockAuto and GMPartsDirect only list a TB (with TPS) and not a seperate TPS for 2005 5.3's

Can I use a later model TB on my motor - one that has a seperate TPS ? Like the ones for the 6.0L 2008+ TBSS's ?

Thanks for any help

Alan W

 

[AtlWrk]

Does your mechanic have specific diagnostic information pointing to a faulty TPS beyond just the P0121 code? Are there any other codes?

I ask because it is extremely unlikely that the throttle position sensor is at fault. The PCM uses a variety of sensors and assumptions to calculate an expected airflow. When the data doesn't add up it knows something is wrong. What's unfortunate is that GM named this DTC "Throttle Position (TP) Sensor 1 Performance" which leads a lot of people to automatically assume that's the culprit when the reality is that the TPS is one of half-a-dozen potential causes. Loose intake seals, cracked hoses, dirty MAFs, faulty IAT sensors etc, can all cause a P0121.

If it is in fact the TPS, the entire throttle body does have to be replaced as a unit. The TPSs (there are two) are integrally built into the unit and are not seperately serviceable. In the absence of any other codes indicating a problem with the throttle body I would put my money on it NOT being the cause.

 

[SSportWagon]

Does your mechanic have specific diagnostic information pointing to a faulty TPS beyond just the P0121 code? Are there any other codes?

I greatly appreciate yours and anyone elses help resolving this problem. I hate throwing parts at a problem hoping I hit the mark ...

There are No other codes - just the P0121 and the CEL had gone on and off 3x times in the past 2 weeks with no other physical indications of any thing malfuntioning. Drives like it always has ...

I ask because it is extremely unlikely that the throttle position sensor is at fault. The PCM uses a variety of sensors and assumptions to calculate an expected airflow. When the data doesn't add up it knows something is wrong. What's unfortunate is that GM named this DTC "Throttle Position (TP) Sensor 1 Performance" which leads a lot of people to automatically assume that's the culprit when the reality is that the TPS is one of half-a-dozen potential causes. Loose intake seals, cracked hoses, dirty MAFs, faulty IAT sensors etc, can all cause a P0121.

If it is in fact the TPS, the entire throttle body does have to be replaced as a unit. The TPSs (there are two) are integrally built into the unit and are not seperately serviceable. In the absence of any other codes indicating a problem with the throttle body I would put my money on it NOT being the cause.

I am off until after new years so I have some time to play with this - what is the recommendation to trouble-shoot the issue ?