94 SC 4R70W Tranny Code 618

tedallen

Registered User
My O/D Off indicator started flashing continuously yesterday morning while driving to work. If I toggled the O/D On/Off switch, their would be a slight shudder, but the light would remain flashing and the tranny stayed in 3rd gear. The light cleared after the car was shut off and restarted. However, on the drive home it came on again. I made a stop, shut off the car, restarted it, and the light did not come on again the rest of the way home and I believe the car was shifting into overdrive. I drove it again this morning without the light coming back on, but when running a KOER test, continuous memory code 618, Transmission problem (2-3 shift error), is present. The transmission fluid level looks good. Just last weekend I replaced the plugs, wires, installed I/C tube gaskets, and replaced a defective vacuum line which required me to disconnect accelerator cable from the throttle body. I just mention these items in case I could have disturbed something external that might cause this condition.

I have also noticed a symptom, particulary when the tranny is cold, such that after coming to a stop, when I depress the accelerator, the tranny acts almost as if it is in neutral for a couple of seconds then engages (this is with the shifter in Drive).

I had a fluid exchange done on the vehicle approximately 15,000 miles ago, and the vehicle has approximately 173,000 miles on it. The torque converter was replaced twice while under warranty, other than that, no other work has been done on it.

Any assistance is greatly appreciated.
 
Thanks for the reply Dirtyd0g. I have an update. It appears that even though the O/D Off indicator comes on and flashes, that you can still engage/disengage O/D with the switch and the tranmission is still shifting into O/D. The indicator came on a couple of times again today, and once it comes on it stays on until the ignition is shut off.

In your reply you mentioned that it was most likely the direct clutches slipping. How major of a job is this to remedy? Does the tranny have to be removed or can it be repaired/adjusted by dropping the pan? Thanks again to everyone for their assistance!
 
I wouldn't even repair that transmission. Get a trans from a 98up 3.8 liter mustang. Install your linkage,internal electronics, and if required output speed sensor (not vehicle speed sensor just make sure you use the right gear) and install that into the vehicle. You can rewire your vehicle to use the later model electronics,but then you will have to make your old tcc solenoid work in there because the resistance is different. You may have to use a different speedometer gear because the mustang tranny will have 8 tooth output where your tranny has 7.Unless you have 3.55 or numerically higher gears that can be fixed by just changing speedometer gears.
Alan
 
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