2003 GT tranny issue.

[FLMedic79]

Hey Guys, Im new to this site and to owning a Mustang.

I just bought a 2003 GT with about 34K miles on it. It is an automatic tranny. Driving 70-80mph the transmission just started droping a gear from O/D back into 3rd. It does this repeatedly. It will shift back into O/D then drop a gear again.

If I press the button on the shifter to turn the O/D off, then turn it back on again, it will go into O/D for a split second then drop back out of O/D again.

Friends of mine said it could be in the overdrive button/switch itself. Im looking for some help/suggestions in the matter. Thank you guys!

 

[wmburns]

Check automatic fluid level/condition

Start by checking the fluid level. Check with the transmission warm/hot, in park, car level.

What is the condition of the fluid? Bright red and sweet smelling? Brown and burnt smell?

A suprising number of automatic transmission problems are rooted with fluid issues.

IMO, it is wishfull thinking this problem is as simple as the OD switch. Consider that if the switch were broken, the transmission would never try on it's own to go into overdrive. The fact that it does, suggests that OD is enabled. To confirm, use an ODB2 scanner to ask the PCM. There is a PID for the overdrive mode.

 

[FLMedic79]

The tranny fluid is brand new, bright red and smells new as well. When I bought the car, they serviced the transmission, changed the fluid and filter.

I also checked the cold/hot levels this morning. They were par.

 

[JerseyTrueBlue]

Best thing you could do is try a scanner, if you don't have one take it to autozone. Do you have a check engine or any other dummy lights on?

 

[FLMedic79]

Nope, not even when it down shifts out of overdrive..No lights, nothing?

 

[jlds91389]

what kind of tranny fluid did they use? did they change the filter to?

 

[FLMedic79]

I dont know what type of fluid they used....Im assuming the ford dealership would put the right type in LoL. Yep, they replaced the filter aswell. I read someone elses thread with the same problem, and the answer ended up being some sort of modulator valve in or on the tranny? Maybe?

I just switched from the dark side...I have only ever owned Z-28's.