[RubbleSpeed88]

My 98 Mustang GT is giving me a code P1729- 4X4 Low Switch error. Does anyone have ANY clue what this means?! I have had mechanics look at and don't know what it is. I know it has something to do with the transmission, I have a 4 speed auto with a shift kit, a harden impact, and a 2250 stall. But I have a mustang, it doesn't have 4 wheel drive! It makes no since. This code has been on there for like 5+ months, and just recently my tranny stopped shifting from 2nd to 3rd, are these related? Any help would be appreciated!

[kilog55]

more then likely they are related to each other its probly just a generic code for a downshift circuit

[nyuk98gt]

RubbleSpeed88:

I have had that code for years. It doesn't mean a thing for our cars.

The 2-3 shift may be a solenoid problem but then a solenoid code should pop up/OD light will flash. The ATSG gives a lot of possible causes for a 2-3 shift problem: solenoids, OSS, MLPS, gasket leaks, 2-3 accumulator damaged or stuck (easy to check), valve body bolts not torqued correctly, valves in the valve body, etc. Some of these things can be easily checked.

HTH,

Chris

[RubbleSpeed88]

Actually my OD light does randomly flash sometime. So what does that mean? A solenoid is out? How can I fix it?

[nyuk98gt]

RubbleSpeed88:

An intermittent flashing light means that the problem comes and goes (and I'm not trying to be funny). It could be anything from low fluid to high fluid (causing foaming), a temperature issue, a mechanical issue, an electrical issue, .... You really have to read the code when the OD light is flashing. When the light goes out, the code has been cleared and you'll never know the reason the light came on.

Start with the level. Make sure the fluid level is correct. Low fluid can cause shifting problems and it is hard on the pump. Excess fluid can cause foaming and this is not good for the pump, either. Check the level (several attempts are normal) when the fluid is cold (this is my preference). Add 1/2 a PINT at a time and don't overfill. If it is overfilled, you can use a MightyMite handheld vac pump to remove it.

Chris