1994 GMC Sierra Why does transmission shift sometimes and n

Tiny
DOOGIE06
  • MEMBER
  • 1994 GMC SIERRA
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
Transmission will sometimes shift out of second into third and other times not. I had the computer scanned and there were no codes to read. Everything is A okay. I know it is a electrical problem but where does one start to look. What should the volt reading be on the VSS. The reading I had was 0.5 volts. And some one has also suggested the ignition switch on column, (not the lock cylinder). Complex by problem. Any suggestions.
Thursday, July 22nd, 2010 AT 7:15 AM

3 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Hi doogie06,

Thank you for the donation.

Which engine and transmission variant do you have?
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Thursday, July 22nd, 2010 AT 7:46 AM
Tiny
DOOGIE06
  • MEMBER
  • 2 POSTS
Engine is a 6 cylinder 4.3
Transmiision is 4L60E or also known as M30.
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Friday, July 23rd, 2010 AT 10:00 AM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
The reading for the VSS should be 12 volts.

The output from PCM VSS sensor should vary between 0 to 5 volts.

Where did you test the voltage from?
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Friday, July 23rd, 2010 AT 11:05 AM

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