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Pulse width modulation valve quesion.

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Old 05-02-2010, 12:08 PM   #1
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Default Pulse width modulation valve quesion.

Can a pulse width modulation valve cause my truck to feel like it has a slipping converter? It seems sluggish and wont downshift past third at 65, even when I go to wide open throttle.
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Old 05-02-2010, 12:09 PM   #2
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Its a 2000 GMC Sierra 5.3 4x4 1/2 Ton.
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Old 05-02-2010, 01:25 PM   #3
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you would likely throw a p1870 code (does not illuminate the CEL) if you were getting that much slipping in the converter. You would also experience full pressure neck breaking shifts from my experience.
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Old 05-03-2010, 12:20 AM   #4
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Yea I cant check those types of codes. But my pressure does spike quite alot. But only sometimes a real hard shift.
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Old 05-03-2010, 01:28 AM   #5
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Quote:
Originally Posted by sierraZ71SS View Post
Yea I cant check those types of codes. But my pressure does spike quite alot. But only sometimes a real hard shift.
If you were throwing that code, it would be maxed all the time.
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Old 05-04-2010, 01:26 AM   #6
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Well the pulse width modulation valve contols the amount of torqure converter lockup. Not the transmission pressure.
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Old 05-04-2010, 01:45 AM   #7
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FYI, a slipping converter(or band) will not set a P1870.

Not sure if that helps you or not, but it is true.
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Old 05-04-2010, 09:12 PM   #8
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Quote:
Originally Posted by sierraZ71SS View Post
Well the pulse width modulation valve contols the amount of torqure converter lockup. Not the transmission pressure.
right but the code i mentioned will control pressure


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FYI, a slipping converter(or band) will not set a P1870.

Not sure if that helps you or not, but it is true.
when my converter took a dump it set the code.
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Old 05-05-2010, 12:10 AM   #9
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Cool, but I've seen plenty of others that did not set the code, so.........

We're both right.
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Old 05-09-2010, 11:51 PM   #10
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When I first got my 99 I noticed the converter was cycling a lot. Every 3-15 seconds it would unlock then relock. No codes and the IIRC I did the P1870 test with the Tech 2 and it all checked good. I installed a transgo HD2 shift kit in it and among other things it shoved that stupid little valve out of the way and made the circuit either on or off and its worked flawlessly ever since. Lockup feels like it could be a 5th gear.
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