Vehicle speed sensor?

MICHAEL WELCH

MEMBER
3 POSTS
1994 MERCURY SABLE
6 CYL
FWD
AUTOMATIC
108,800 MILES

Hello, I relied on you guys recently and you helped out, another problem that I have is transmission on a 94 mercury sable with 3.8 liter acted up couple of months ago, harsh shifting and everything else, changed that vehicle speed sensor, you start it up and you can drive without any problems shifting thru the gears like normal, but, when you come to a stop sign or stop light and come to a complete stop you feel the trans downshift the way if should shift and everything seems normal, but if your coming up to a light and your speed is maybe 2-4 mph and give if the gas, you feel the trans slip and then engage and your off and running untill the next light, we scanned the car and code #624 came up, actully we scanned it from 4-5 different people and everybody came up something different, somebody even said we had a wheel sensor bad, other than that the car runs and shift fine, 1(one) tranmission guy said we need a rebuilt tranny, I don't think so

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Thursday, September 17th, 2020 AT 11:54 AM (Merged)

JACOBANDNICKOLAS

MECHANIC
109,732 POSTS

My concern is this. If it slips, the first thing one thinks of is worn clutch packs. That is what the one guy is hoping you think when he says it needs rebuilt.

Let me explaine what it is. The electronic pressure control (EPC) solenoid is a variable force style solenoid. ( An electro-hydraulic actuator combining a solenoid and a regulating valve.)

The powertrain control module (PCM) controls the EPC solenoid.
Its action causes the solenoid to regulate both the transmission line pressure and line modulator pressure. This is done by producing resisting forces to the main regulator and line modulator circuits. The purpose of the two solenoids is to control clutch application pressures. Your code (EPC Circuit failure) tells me there is a break down in communication between the EPC and the PCM or the EPC needs replaced. To access it, you need to remove the trans pan.

I recommend having that checked. It could be causing low pressure or a delay when it shifts, causing a slip. Does your trans need overhauled? I say no. Have that checked and let me know what you find.

Joe

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Thursday, September 17th, 2020 AT 11:54 AM (Merged)