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kalamykid
kalamykid, Shop Owner/ Tech
Category: Car
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Experience:  I HAVE OWNED MY OWN SHOP FOR OVER THREE YEARS. I HAVE THE TOOLS AND SOFTWARE TO ANSWERE ALMOST ANY Q
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2003 Chevy: auto transmission..RPM..up 300 to 500 RPMS..back down

Resolved Question:

I have a 2003 Chevy Silverado V6 auto transmission. When I travel between 50 and 60 MPH. The RPM fluctuate up 300 to 500 RPMS and back down continuously. If I put it in a lower gear and travel the same speed the fluctuation doesn't occur. If I press on the break slightly while maintaining 50 - 60 MPH the fluctuation doesn't occur. Any suggestions what this may be???
Submitted: 6 years ago.
Category: Chevy
Expert:  kalamykid replied 6 years ago.

Kalamykid :

this is going to be the lock up converter dropping out and kicking back in.

Kalamykid :

This can be due to a bad torque converter, bad lock up solenoid, or a bad valve body.

Kalamykid :

Does the check engine light come on and stay on when the engine is running?

Customer:

The check engine light never comes on.

Kalamykid :

It does not come on when you turn the ignition switch to the run position and leave it there with out starting the engine?

Customer:

I had to go check! It does come on if you turn the ignition switch to the run position. It shuts off as soon as you turn over the engine. If i turn it off completely then and immediately turn the ignition switch to the run position again, the engine light doesn't always appear. I tried it several times. I had to wait several minutes then tried again and the engine light appeared.

kalamykid :

With this information, I will have to say that your problem can be in the pcm itself. the check engine light should always come on with the switch in the run position, and the engine not running, then go out when the engine is running.

Customer:

Sorry, what is a PCM?

kalamykid :

This will be a hard thing to check to find out if you donot have a scanner that will give you live data, and it will be best to take it to the dealer and have them diagnose htis problme.

kalamykid :

The pcm is the computer for the engine and trasn.

kalamykid :

Pcm stands for power train control module.

Customer:

OK. I appreciate your time.

kalamykid :

I hate the " it is best to take it to the dealer" but in this case it is your best bet.

kalamykid :

Make sure to let them know the check engine light does not always come on when the switch is in the run position.

Customer:

I appreciate and respect your honesty.

Customer:

Thanks

kalamykid :

You are very welcome.

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