1992 Toyota Previa Repair Question
1992 Toyota Previa Overdrive Problem
1992 Toyota Previa 4 cyl Two Wheel Drive Automatic
Recently my Previa has been shifting in and out of overdrive. Sometimes only sporadically, more often it is beginning to shift in and out every 1 or 2 seconds. When I push the overdrive button to turn it off, it runs ok, but I can still feel a sort of 'chugging', but not anything like the shifting in and out when in overdrive, which becomes a head banging, neck jerking experience. I took it in for service to a transmission specialist. No codes appeared faulty on the diagnostics, so on a 'hunch' they replaced the throttle control valve. This did not fix the problem. They told me it may be an electrical/electronic issue that they were not capable of assessing, possibly requiring a new computer. Any suggestions?
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Perform the following and see if you can come up with anything. Monitor is the trans slips when shifting into OD when shifting into D. Repeat a few times to be sure.
TRANSMISSION SHIFT TESTING
NOTE: Perform manual shifting test if no fault codes exist. Manual shifting test determines if problem area is in electrical circuits or a mechanical transmission problem.
1 . With ignition off, disconnect electrical connector for solenoids from rear of transmission. See Fig. 7 .
2 . Road test vehicle and ensure transmission gear changes corresponds with shift lever position. See GEAR APPLICATION table.
3 . If abnormality exists, a mechanical transmission problem exists. If all gears are correct, perform trouble shooting in accordance with the symptom. Turn ignition off.
4 . Reconnect electrical connector. Clear fault codes from ECT ECU memory, as disconnecting electrical connector may set a fault code.
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