2002 Transmission Stalling

[rdh2]

This is a repost of a thread I started awhile ago, but never finished the troubleshooting because of work training and moving.

The Car: 2002 Taurus 3.0L 2V, 140000 miles

The Problem: While driving on a long distance trip, I had a transaxle light flashing along with poor acceleration as I was entering a freeway. The problem cleared itself in 3/4 mile, as there was no place to pull off. Fast forward to today. The car has been parked due to lack of my time. If the gear shift is placed in R, D, or 2, the engine stalls. If it is placed in 1 it does not stall. No check engine or transaxle light is on.

As part of troubleshooting, I disconnected the 9 pin D transaxle connector from the top of the trans. The check engine light and the transaxle light are now on, but the engine does not stall in any gear.

I am certain the TCC is engaged with the connector connected, because of the shudder and the feeling of the trans causing the stall.

I've read the manual, but since I do not have a transmission tester or OBDII scanner available, I'm not able to get far in the troubleshooting.

The solution: This is where the experts on this board can help. Are there any other items I can check at this point? Does this sound like a simple component failure or major trans work?

[Millermagic]

Sounds like maybe your toruqe converter solenoid is locking up the torque converter. When you put it in D or OD and it stalls, before it stalls, can you hit the gas and go or will it stall?

[rdh2]

Originally Posted by Millermagic

Sounds like maybe your toruqe converter solenoid is locking up the torque converter. When you put it in D or OD and it stalls, before it stalls, can you hit the gas and go or will it stall?

Actually, I have tried that and it stalls so quickly I can't hit the gas fast enough to keep it going. I've tried it in R, 2, and OD but it stalls very quick. I guess that in 1, the TCC is disabled. In fact, if I shift from P or N to 1, I can feel the stall starting just by passing through the other gears.

[Millermagic]

The thing with 1 is the torque converter is unlocked until you let off of the gas. Once you do that, it locks up and allows for engine braking.

[rdh2]

Originally Posted by Millermagic

The thing with 1 is the torque converter is unlocked until you let off of the gas. Once you do that, it locks up and allows for engine braking.

Is there any way to isolate the problem to what is causing the TCC to lock? Since the disconnection of the 9 pin trans connector keeps the trans from stalling the engine, It would appear the TCC solenoid is not stuck. Any suggestions as to possible component/sensor issues and how to check?

[rdh2]

It appears the PCM is grounding the TCC solenoid at all times. There is ground available at pin 6 of the trans connector. Does anyone have reference numbers for what the Trans Fluid Temp (TFT) sensor should be hot cold?

[shorod]

Are you sure it is a 9-pin connector, or might it be a 10-pin? I pulled up the wiring diagram for the transmission in a 2002 Taurus and it shows a 10-pin D-connector, and pin 3 is for the TCC, pin 6 is Shift Solenoid B. Pin 4 is not used, so there are only 9 wires going to the connector, but there are 10 positions in the connector.

If you'd like me to send you a PDF attachment of connector C199, send me a private message with your e-mail address and request.

I don't find anything in the service manual regarding specs for the TFT sensor. I find it mentioned as being an integral part of the transmission control body, but nothing on what resistance/voltage drop to expect for certain temperatures.

-Rod

[rdh2]

Originally Posted by shorod

Are you sure it is a 9-pin connector, or might it be a 10-pin? I pulled up the wiring diagram for the transmission in a 2002 Taurus and it shows a 10-pin D-connector, and pin 3 is for the TCC, pin 6 is Shift Solenoid B. Pin 4 is not used, so there are only 9 wires going to the connector, but there are 10 positions in the connector.

If you'd like me to send you a PDF attachment of connector C199, send me a private message with your e-mail address and request.

I don't find anything in the service manual regarding specs for the TFT sensor. I find it mentioned as being an integral part of the transmission control body, but nothing on what resistance/voltage drop to expect for certain temperatures.

-Rod

My bad, Rod. It is the 10 pin, but only 9 are used. And it is pin 3 I checked. When I looked at the diagram, the TCC solenoid was listed as item 6. Typos on my part. So, any ideas on what to check next as to why the PCM is signaling the TCC to always lock up, except in 1?

[shorod]

That is interesting. Since in 1st the TCC is not getting a ground, the driver circuit in the PCM must not be shorted. It must be due to inputs to the PCM, such as the TFT (as you mentioned) and I think probably the Vehicle Speed Sensor (VSS). I don't remember what all sensors are involved in the determination of TCC lockup. I'm far from a transmission expert, sorry.

-Rod

[rdh2]

Originally Posted by shorod

That is interesting. Since in 1st the TCC is not getting a ground, the driver circuit in the PCM must not be shorted. It must be due to inputs to the PCM, such as the TFT (as you mentioned) and I think probably the Vehicle Speed Sensor (VSS). I don't remember what all sensors are involved in the determination of TCC lockup. I'm far from a transmission expert, sorry.

-Rod

Thanks, Rod. After searching many posts on this site, I eliminated the VSS because the cruise control has always worked fine. It still works now with the trans in 1. The manual lists the following PCM inputs for trans operation: VSS, output shaft speed, MAF, turbine shaft speed, trans range sensor, engine coolant temp, and intake air temp. I really hate the thought of taking to a shop when I have this gut feeling it is a simple component change, but I am at the end of troubleshooting. So replacing these sensors on my hunch is cost prohibitive. Thanks for the help.

[shorod]

Well, I did a bit more looking in the service manual, and the diagnostic routine for a torque converter that stays locked is below. This information was in table format and the formatting did not paste, so it's a bit difficult to follow, but still doable. I'm not sure this will be of much help though since you probably don't have access to the dealer transmission tester.

-Rod

TORQUE CONVERTER OPERATION CONCERN: ALWAYS APPLIED/STALLS VEHICLE Possible Component Reference/Action 241 — ELECTRICAL ROUTINE Powertrain Control System · Carry out the Torque Converter Clutch Operation Test. Refer to Torque Converter Diagnosis in this section.
· Electrical inputs/outputs, vehicle wiring harnesses, powertrain control module (PCM), TFT, TSS, ECT, MAF, TCC solenoid, and digital TR sensor
· Run OBD. Refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual for diagnosis. Carry out Pinpoint Tests B, C, and F. Refer to Pinpoint Tests — Non OSC Equipped Vehicles in this section.
341 — HYDRAULIC/MECHANICAL ROUTINE Main Controls · Bolts out of torque specification
· Tighten bolts to specification.
· Gaskets—damaged, off location
· Inspect gaskets. Repair as necessary.
· Torque Converter Clutch Control Valve or Plunger—stuck, damaged
· Inspect for damage. Repair as necessary.
· TCC Solenoid—not functioning correctly
· Activate solenoid using the Transmission Tester. If solenoid operation cannot be felt when placing hand on solenoid, install a new solenoid.
Torque Converter · No end clearance
· Inspect for damage. Repair as necessary.

[shorod]

Oooh, oooh, I just found the test procedure for the TFT and other sensors. If you'd like to send me a private message with an e-mail address for you and your request, I can send you the PDF file. It even includes a table with resistance range per fluid temperature!

-Rod

[rdh2]

Just an update for anyone interested. Pulled codes and found they were self induced from unplugging harness. Tested the sensors, etc. with no defects found. Removed power wire from TCC solenoid at connector and it works ok. Appears to be the TCC solenoid is internally shorted to ground. Now for the fun job of the repair.

[rdh2]

Originally Posted by rdh2

This is a repost of a thread I started awhile ago, but never finished the troubleshooting because of work training and moving.

The Car: 2002 Taurus 3.0L 2V, 140000 miles

The Problem: While driving on a long distance trip, I had a transaxle light flashing along with poor acceleration as I was entering a freeway. The problem cleared itself in 3/4 mile, as there was no place to pull off. Fast forward to today. The car has been parked due to lack of my time. If the gear shift is placed in R, D, or 2, the engine stalls. If it is placed in 1 it does not stall. No check engine or transaxle light is on.

As part of troubleshooting, I disconnected the 9 pin D transaxle connector from the top of the trans. The check engine light and the transaxle light are now on, but the engine does not stall in any gear.

I am certain the TCC is engaged with the connector connected, because of the shudder and the feeling of the trans causing the stall.

I've read the manual, but since I do not have a transmission tester or OBDII scanner available, I'm not able to get far in the troubleshooting.

The solution: This is where the experts on this board can help. Are there any other items I can check at this point? Does this sound like a simple component failure or major trans work?

Final update/fixes on the problem.

After much troubleshooting and headbanging , the transmission causing the engine to stall problem is solved.

It turned out to be a mechanical problem. The pump shaft bearing in the transmission was bad, allowing the shaft to have excess play, which tore the shaft seals. The leaking past the seals bled off enough pressure so the TCC would not release. With the transmission connector disconnected, the EPC line pressure increased enough to prevent stalling, but then of course the trans wouldn't function correctly due to the PCM being disconnected.

By replacing the pump shaft, bearing, and seals, the transmission no longer causes the engine to stall in gear, the shifts are smooth, and I have my Taurus back. A Merry Christmas, indeed.

[shorod]

Wow, that was an interesting problem, and the forum appreciates you taking the time to post a follow-up with the fix. Glad you have your car back!

-Rod