Rick's Free Auto Repair Advice

Transmission shifts late

Fix Ford Taurus transmission that shifts late and hard

If you own a Ford Taurus and the vehicle is shifting hard into 2nd gear or the shift is occurring late, here’s how to check it out. You’ll have to raise the vehicle on a hoist and test it while running. This can be dangerous, so take safety precautions. You’ll be testing with a digital multimeter. Find the violet/orange wire at the PCM or the transmission solenoid connector on top of the transmission. The PCM provides ground on this wire to activate 1st gear. Then, when it’s time to shift into 2nd gear, the PCM removes the ground from this wire and it should then read battery voltage. If you see this behavior, ground disappears and voltage goes to battery voltage, but the shift is still delayed, the problem isn’t in the PCM but is an internal fault either in the valve body or the intermediate clutch. However, if it appears that the PCM is late in changing the ground, check the throttle position sensor (TPS)

throttle position sensor, TPS

Throttle Position Sensor located on the throttle body

and the Mass airflow sensor (MAF). Here’s how
Check TPS output voltage. It should be .8-1.0 volts with fully closed throttle. Slowly open the throttle and watch the voltage sweep to 4.5 volts at full open. If you don’t get those readings, replace the TPS. Next, unplug the MAF sensor and drive the vehicle. That will force the PCM to operate off of factory default programming rather than live feedback from the MAF.

mass airflow sensor, MAF sensor

Mass Airflow Sensor located in the air duct between the air filter and throttle body

If the shifting problem goes away, you can try cleaning the MAF. See the procedure here. If that doesn’t work, replace the MAF. Finally, check the condition of the transmission range selector (TR).

transmission range selector, transmission range sensor, TR sensor

Transmission Range Selector located on top of transmission


© 2012 Rick Muscoplat


Posted on by Rick Muscoplat

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