B2norma

2004 Mustang GT

The car was shifting fine on the way home from work yesterday. Started it up this morning, and noticed it jerked pretty hard when I put it in reverse to back out of the driveway. It jerked hard again when I put it in drive. After going about fifty yards, I noticed it wasn't shifting. Drove around the block a couple of times getting up to around 4000 RPM, and nothing. Put about half a container of Lucas trans fix in it, and still nothing. Any ideas or help on this would be greatly appreciated.

08'MustangDude

That's the way it happens, works one day, then boom, done...

Z28KLR

Trans in and of itself is likely fine, sounds to me as though the issue lies within the valvebody or something related such as shift solenoids. Unfortunately that's about the extent of knowledge I have on these things.

WJL

what does the transmission fluid look like, is it burnt it should be bright red/pink

another question is the O/D light on or flashing ? check for codes there is a button on the shift lever for O/D try turning it on and off. what does the light do when you turn it on and off?

If the trans fluid looks good and doesn't smell burnt it could just be a solenoid but should throw a trouble code

not a big fan of trans fix (snake oil)

FYI the 2004's has 4RW75 trans

Good luck and let us know what happens

B2norma

The transmission fluid was changed about 45K miles ago. It still pink and doesn't smell burnt. The O/D light comes on and goes off like normal. Thanks for letting me know about the transmission type.

I'm starting to consider a rebuild kit. Anyone have kit suggestions? Monster Transmission's kit seems high quality, but is very pricey.

http://www.monstertransmission.com/A...ox_c_5807.html

Derf00

From a dead stop , put the car manually into 1st, and gently accelerate to say 20mph. While accelerating and maintaining that speed, can you shift into 2, 3 and D? If you can can, then one of internal solenoids or servos has failed on the tranny . Solenoids electronically controls and/or command the gear the car is in or needs to be in. When that fails, certain gears cannot be selected.

If the car won't upshift when you manually shift it, then you most likely have a mechanical failure within the transmission.

*Disclaimer, testing it in this way may cause addtional damage...however, considering you are already looking at fixing it (Rebuild), it's gonna get fixed no mater what so...I'd go for it.

B2norma

I just tried, and the car shifts from 1st to 2nd fine. When shifting from 2nd to D nothing happens. Tried it a few times, and every time when I go from 2nd to D nothing happens. Could this still be a solenoid? Thanks.

sweetbeats

That sounds like a solenoid issue. Sometimes it can be a failure of the solenoid body (like a crack that allows fluid to go where its not supposed to go causing proper valve actuation to fail), or other times it can be gunk or some other foreign matter restricting a valve from actuating or clogging a port. But I'd put my money on a problem related to the valve body if you have no trouble codes or O/D light flashing, the fluid looks/smells good, and you can still get *some* positive shifting.

My 2p.

Derf00

I forgot it's a 4 spd. 1, 2, D(3) + OD (4).

Good news op, the Solenoids aren't too expensive on this transmission. About $100 for all three parts https://www.rockauto.com/en/catalog/...+solenoid,8476

Given that you can shift from 1 to 2 and there's not other noises it could very well be just the a solenoid or plugged valve body passageway. When was the last time you had the tranny fluid flushed. It won't make a difference now but gunk build up can and will plug up passageways or freeze up solenoids.

If you're going to drop the pan, you may as well pick up the solenoids and a remaned valve body. That does get a bit more pricey with the valve body but it looks like it comes with one of the solenoids which means you can skip buying it separately (Dual Shift Solenoid). I don't recommend trying to service the one you have because it's of unknown condition and if you don't already have the proper tools to check, repair, and verify the repairs, you'll end up costing yourself way more time/money than it's worth.

Worst case scenario, you have to rebuild the transmission in which case you'll need to replace those parts anyways.

B2norma

Alright people, so the last time I drove the car It threw a code (P0068). I saw a couple of places online that blamed the TPS for up-shifting problems, so I decided to replace the TPS before getting into anything more difficult. I'm happy to say the car now shifts like a dream. Thanks for the help to determine it was an electrical problem.