1992 Pontiac Bonneville intermittent transmission shift issue

Tiny
BLAKEWILCOX
  • MEMBER
  • 1992 PONTIAC BONNEVILLE
  • 3.8L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 105,000 MILES
Codes 24 42 26. Car does not come out of 1st or second till after reved up and a purge vent sound is heard followed by a cel then shifts fine but stays in 3rd when decelerating other times it shifts flawlessly. Dash coolant guage reading seem different. Replaced vss
Saturday, November 8th, 2014 AT 8:58 PM

4 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
One code is the vehicle speed sensor which is on the trans and the other one is a quad driver which is part of the pcm there is also a code for est circuit open which leads to the distributor. Have a pro check this out as it may be a bad pcm and replacing It may not be what it needs.
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Sunday, November 9th, 2014 AT 3:41 PM
Tiny
BLAKEWILCOX
  • MEMBER
  • 3 POSTS
With side cover off I checked solenoids a and b with testlight both having current going into them but not out of them even with two known good sensors
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Sunday, November 9th, 2014 AT 3:50 PM
Tiny
BLAKEWILCOX
  • MEMBER
  • 3 POSTS
I was thinking the pcm grounds those and may be a fault in wiring or pcm but you say check pcm first? Then go on too vehicle speed circuit, and est circuit? I payed a guy 120 for a diagnostic in which the car decided to work fine.
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Sunday, November 9th, 2014 AT 3:53 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
I doubt it's what you say a quad driver is an internal part of the pcm or ecm in your case that holds memory sometime it will work other times it won't. Try resetting ecm by pulling fuse for 30 seconds and see if same codes come up. Make sure there areno shorted wires leading from pcm to distributor as well
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Sunday, November 9th, 2014 AT 4:43 PM

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