1988 Pontiac Grand Am no overdrive

1988 PONTIAC GRAND AM
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GENEMONEY
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Transmission problem
1988 Pontiac Grand Am 4 cyl Front Wheel Drive Automatic

1st 10 or 15 mi, car will not shift into overdrive. Seems as though a temp sensor is bad somewhere in or on the transmission or perhaps oil temp sensor. Once the engine/transmission gets good and hot, overdrive works fine. Or if driven real hard, which I'm guessing heats the transmission quicker, overdrive engages sooner. What/where is the culprit?
Nov 5, 2008 at 3:02 PM
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MMPRINCE4000
  • ✓ASE Certified Mechanic
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  • ASE Certified Mechanic
I would change the thermostat. The engine on these
cars must be in closed loop for trans lockup to work.

So either the thermostat or the temp sender is suspect.
Nov 6, 2008 at 6:43 AM
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