Unusual problem of lurching in low gear

AIGER5

MEMBER
1995 FORD TAURUS
6 CYL
2WD
AUTOMATIC
75,000 MILES

My taurus sho has an unusal problem of lurching in low gear just as the car reaches operating temp. Does only on occasion not all the time. Seems to happen most when the weather gets above freezing. Happens just once then runs just fine. Eventually had to replace trans this summer. Shop claimed if was due to my racing and abusing trans, of course. Now rebuilt trans is doing the same thing. Codes indicate bad speed sensors but shop says all is well and refuses further repair

1 Reply

JGAROFALO

MECHANIC
489 POSTS

If the codes indicate a bad speed sensor, then that is probably the problem. Your transmission has TWO speed sensors. The input speed sensor is located near the LEFT axle where it enters the transmission. It is attached to the housing and is connected by a 2 wire connector. The output sensor is located on the right hand end of the transmission case, on the top. This one is a bit hard to reach. It also has a 2 wire connector.

The computer reads these sensors, and compares them to determine what gear the transmission iis in.

If the output sensor is bad, the speedometer will also read incorrectly if at all. If the input sensor is bad, it will cause shifting problems. Once the computer detects a problem with a transmission sensor, it will default to full line pressure. This causes the harsh shifting.

HOWEVER. Before you start hanging sensors, be sure to check the condition of the wiring harnesses leading to the sensors as well as the connectors. Corrosion or damage in the connectors will give erratic readings to the computer, which will in turn default to high pressure. Check the harness for rub spots, chafing, cracking, etc. The sensor is only as good as the connectors and wiring leading from the computer to the sensor.

Good luck!