1999 Transaxle "slipping"

1999 Century Custom, 145,000 Miles, last trans filter/fluid change was at 125,000.

The car was driving fine. My wife stopped at the grocery store and when she left the store the car had no power from a dead stop. It can be described as feeling like a worn clutch slipping on a manual transmission. The 10A "Trans" fuse was blown and the SES light is on. DTC's from the PCM are:

P0740 - Malfunction in electrical circuit for the torque converter clutch.
P0753 - Short to ground, short to battery, or an open circuit in the electrical circuit for shift solenoid "A".
P0758 - Short to ground, short to battery, or an open circuit in the electrical circuit for shift solenoid "B".Replacing the fuse results in the fuse being blown once the car is driven. All wiring to the trans appear to be in good condition. All vacuum lines appear to be in good condition. Fluid level is full. The car has an easier time taking off from a dead stop if you manually shift the trans into first gear, however it is still sluggish.

This would appear to be a short in one of the shift solenoids, the TCC or the wiring inside of the trans.

Since I no longer have access to the equipment needed to drop the subframe and remove the trans side pan, I wanted to run this by you guys to see if you had any additional input before I fork over the $ to have the solenoids and TCC replaced.

Thanks in advance!

JW

Welcome to AF.

It sounds like one of the three solenoids has high resistance or a short since the 12 volt feed fuse (Trans) is popping. 12 volts is always present at ignition on at one side of the solenoid coil. The ground/low to the other side of the solenoid coil is supplied by the PCM module.

If you have a DMM and capable of using it you can measure solenoid coil resistance through the 20 way electrical connector. Remove connector located at top left hand (driver's) side of transaxle and measure at tranny side of connector.

1-2 shift solenoid - pins A-E = 19-24 ohms
2-3 shift solenoid - pins B-E = 19-24 ohms
TCC/PWM solenoid - pins T-E = 10-12 ohms

Readings at 68 degrees F.

Hello there,

Here are the DMM results:

1-2 shift solenoid - pins A-E = 22.4 ohms
2-3 shift solenoid - pins B-E = 22.4 ohms
TCC/PWM solenoid - pins T-E = Could not locate pin "T" !?

Readings taken at 76 degrees F.

The connector has the following pins, clockwise from the top:

E, D, F, A, B, G, C

From pin "E" to the transaxle case results in 2.3 ohms

Driving the car with the connector disconnected results in the same driving issues, however the fuse does not blow (duh).

Thanks again!

My bad! Let me get you the pins for the 7 way connector. Even though you have a '99 model it sounds like you have the older 4T60E autotransaxle. I guess it was 2000 and up that got the 4T65E. Check your SPID label on the back of the trunk lid. M13 is 4T60E and M15/MN3 is the 4T65E.

4T60E
TCC sol - D-E
TCC/PWM sol - C-E
1-2 shift sol - A-E
2-3 shift sol - B-E

SPID label says "M13", so it's a 4T60E

Also, since this started the auto door locks have been acting-up. Before, when you put the car into any gear from Park the doors would lock, then from any gear to Park and they would unlock. Now the locks only work if shifting to, or from Reverse or Neutral.