A-604 problems...... please take a look

[Aries_Turbo]

Hey Guys and Gals....

as some of you know, I built a V6 K car with the 604 cause I had it laying around...

Heres the issue. this morning on the way to work when it went to shift into 4th the car lurched pretty bad like it was trying to select two gears at once and then I no longer had a 4th gear... it just slips now and wont downshift back into third even when I give it gas and pull the lever into D3.

any common 604 issues involving the 3rd to 4th shift. up unto this point it was shifting somewhat rough into 4th but I figured it was a sticky solenoid pack. i was wrong. I tried another solenoid pack from another car and the problem is still there. no 4th gear.

for now (ie till Frank gets me the 543 5-speed he has for me) I'm driving it in 3rd gear (D3) and getting a bit worse mileage but it works fine like that. any help would be appreciated. thanks.

Brian

[Stevien1]

this morning on the way to work when it went to shift into 4th the car lurched pretty bad like it was trying to select two gears at once and then I no longer had a 4th gear... it just slips now and wont downshift back into third even when I give it gas and pull the lever into D3.

So it shifted hard into fourth this last time now it won't go into fourth anymore? Use a scanner and see what codes are stored in the TCM. And of course, check the basics like fluid level, shifter cable adjustment. If you have a scanner, verify the PRNDL switch is showing the correct range selection in relation to the shift indicator.

any common 604 issues involving the 3rd to 4th shift. up unto this point it was shifting somewhat rough into 4th but I figured it was a sticky solenoid pack. i was wrong. I tried another solenoid pack from another car and the problem is still there. no 4th gear.

On the older models, there was/is a problem with the EMCC (electronic modulated converter clutch) causing a shudder in 3rd and a rough engagement in 4th. Chrysler released an updated cal for the TCM and came out with ATF+3 at the time (the current is ATF+4). Solenoid packs don't usually cause a shift quality problem- they work or they don't.

There's a few things that take place in the 604 (41TE) during a regular upshift sequence, it goes something like this....

The TCM commands both the UD and OD clutches on obtain direct (3rd) gear. If the throttle is less than a certain amount (less than 30% IIRC), the TCM will begin to partially apply the torque converter clutch (modulate) untill it decides the conditions are met to shift into overdrive (4th). When this takes place, the converter clutch is released along with the UD clutch, then the TCM commands 2/4 clutch on along with the OD clutch that was already applied. After the shift succeeds and the throttle is not open greater than a pre-determined amount, the EMCC comes on at 100% to lock the converter.

Now that you have an idea of what takes place during, you can start figuring out what's wrong.

-Chuck James

[turbovanman²]

Other common issues, input and output shaft sensors, solenoid pack.

[fleckster]

Other common issues, input and output shaft sensors, solenoid pack.

Chuck pretty much nailed it on what is happening at the 3-4 shift and that goes for all the Chrysler Electronic transmissions.

Simon, the Input Speed Sensor reads off of the spine on the flange of the Input Clutch Hub. The Output Speed Sensor actually reads off the Part Gear itself. While this to parts are splined to shafts, they are not reading the shafts themselves. There more than likely isn't an issue with the speed sensors as one of the them not working would confuse the computer as it is essentially "blind" and the trans would be put into "Limp-In" mode, stuck in 2nd gear. I would bet that there is a problem with the 2/4 Clutch Assembly and you are unable to hold pressure on the piston to engage 4th gear. Of course, it's just a guess. I'd be interested to know when you finally get it out and feel like tearing into it to see what the problem actually is!

[turbovanman²]

I know, Chuck did a wicked job but Brian asked what are common failures, so I listed them,

[Aries_Turbo]

status:

fluid is fine.... mostly atf+4 but with a little +3 in it cause I had no more +4 and I needed to top off.

sensors should be fine and the sol pack as 1-2-3 are smooth as silk and its not in limp mode.

heres what was going on since i had the car together in october. 1-2-3 would be perfect even when cold. going from 3rd to 4th when cold used to be a little rough so Id baby it till warm then it would be ok unless under these conditions:

when Id romp on the car through third and then back off and let it shift into 4th nice and easy, sometimes it would feel like two clutches were on at the wrong time (car lurch a bit) and then it would go into 4th. after this happened a few times, id rail 1-2 and then let it smoothly into 3rd (no issue) and then smooth from 3-4 and most of the time it was fine. sometimes if I recreated the bad situation, it lurched HARD into 4th. so I learned to just be easy on it and not let it happen.

this is where the other day came it (yesterday).... I was passing someone and I was hard on the throttle in 3rd and then easy into 4th. it lurched like a sob and then into 4th... it also would not let me downshift back out of 4th and then started slipping if I gave it the throttle in 4th. so I pulled over and it was then in limp mode... i assume cause the input and output speeds were so different.

so what I did was put it in d3 (or "2" cause its a k car steering column) and it drives perfect.... it just revs the motor more.

as for the scanning of the tcm.... its a kcar... there is no ccd bus connector under the dash. i'll have to find my pinouts and make a connector and scan it. my buddy steve has the correct cables and cartridges to scan it.

i was just wondering if there was any valves in the trans that got upgraded cause they caused this issue in earlier models that I could fix.

i dont have the time to tear the trans down as this is my driver right now and all of my other cars need other things fixed on them (aargh).

Frank has a 543 for me but he isnt home yet.

i have all the stuff to convert it to 5-speed so I wont have to deal with this much longer.

thanks

Brian