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Discussion Starter #1
Hello everyone, I have a 2003 Stratus Sedan 2.4 A604 transmission. My problem is I have a very harsh 4-3 downshift, everything else on the trans works like new, smooth upshifts, smooth lockup and smooth downshifts except for the 4-3 shift. It happens when decelerating and I hit about 30MPH, If I switch it to auto stick mode and manually put it in 4th gear then shift down to 3rd it's even worse, at any speed and any throttle position, tried from 20mph up to 70mph, same thing, just a huge thump, kind of like the wheels locked up for a millisecond and the dashboard makes a cracking sound everytime from the jolt.

Anyways, this started happening a couple days ago, the transmission had 197k miles on it so I figured it was probably worn seals, maybe a pump failure, fluid breaking down, I'm wasn't sure. I understand as much about how the insides of transmissions work as much as I understand how women work. So I pulled a used transmission out of an 03 PT cruiser at the junkyard with 90k on it, got the torque converter from it too all for $50 thinking this would fix the problem. Well it shifts like new now, no more mildly harsh shifts or harsh lockup like the old one, but that harsh 4-3 downshift problem is still there on this second trans also.

Now I'm at a loss, could it be possible that the second trans also has the same failure as the first one did even though every other shift on it is flawless, along with all new fluid and filter, or could it be something external to the transmission like a sensor, wiring, maybe even the solenoid pack? I haven't heard too much about pump failures on these units but maybe low fluid pressure, I have no idea. All the sensors and solenoid pack came with the second transmission and I didn't touch them, but the wiring harness is the same old one.

Additional information:
No codes stored, at least with the key trick.
Once it downshifted to 3rd all by itself at about 50MPH when I was going around a bend, wasn't in autostick mode.
The speedo was working perfectly the whole time, never saw it jump around or drop to 0.
Drove it about 40 miles so far with the new transmission in, highway and city.
Never went into limp mode once, the auto downshift to 3rd was weird but upshifted after a few seconds.

Hopefully I added enough information here, always better to have more than not enough I'd say. If anyone has any ideas where to look or what causes only a 4-3 hard shift when everything else works perfectly, I would really like to know.
Thanks for your time and reading all that.
 

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Discussion Starter #3
Ah perfect, I will print this out and bring it to my dealer.
I'll report back with what they say and if it fixed the problem or not. Thanks so much for your reply.

EDIT: Just got back from the dealer, they said they'll be happy to look at it for $110 to hook it up but they aren't sure if my build date needs it or not. I think July 10th 2003 was the magic date. They said they will flash it if it needs it and do a quick learn.

Since the PCM uses fuzzy logic, is it possible it can re-learn the second transmission in a couple of weeks and go back to normal? From what I read so far there's no way to quick learn 95 and up models without the use of a DRB-III or equalivant tool. If I have to pay $110 then I have to do it, but if there's a cheaper way around it I'd deffinatly go for anything.
 

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Discussion Starter #5
Ah that must be it then for sure. My build date code is 090609 so i'd guess it's September of 2002, if it was 2003 it would probably be an 04 model. It does have the NGC all in one PCM .

I read the CVI values for the underdrive clutch must be set pretty high in the PCM for a harsh 4-3 shift, it's too bad there's no way to reset them all to a default value of 50 or so with a battery disconnect or simple trick.

What I'd guess at this point is it's probably best to have the PCM flashed and updated then since there is one available, it should only be a one time thing and any future transaxle I install, rebuilt or the one I took out which may have nothing wrong with it after all will work perfectly after a flash.

I also do have access to the original PCM in the 03 PT Cruiser too where the second transaxle came from, both are Huntsville units, I've heard they should interchange but if the part numbers match and the PT has a newer build date, it should have the firmware update already applied and can be had for only $25, much cheaper than the dealer wants. Just thinking out loud here, I don't know if it will work or i a good idea, but I like getting things done right but also as cheap as possible as long as it works.

If anyone has any feedback on anything, please let me know.
 

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Yes, born September 6th, 2002 @ 9 am in Sterling Heights, Michigan.
The only real concern of swapping PCM's between cars is if the donor PCM has the security system (VTSS) option and your car doesn't. The VTSS-enabled PCM will 'poison' the non-VTSS BCM with the unsupported VTSS option and can't be undone. The same goes for swapping BCM's between vehicles. The car will exhibit no-start and horns/headlamps going off. Then both the PCM and BCM would have to be replaced with non-VTSS modules to cure the 'infection'. Once enabled, the VTSS can't be disabled.
If you have the gray SKIM key or the donor PCM has the SKIM key, then the 4-digit secret key code for your car would have to be entered by the dealer DRB III scan tool.
VIN and mileage are stored in the PCM, but aren't critical to operate the car. The scan tool also can change these to match your car. The dash odometer mileage is stored and counted in the BCM, so the PCM mileage is kept as a separate record. To complete any dealer service, you would want the latest and greatest software level for all your vehicle's modules.
 

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Discussion Starter #7
Makes perfect sense, I forgot all about the VTSS nightmare. It doesn't have a skim key at least. But swapping PCMs isn't a sure way of fixing it. Today I'll start calling around other dealers and seeing what prices they give me. I'll also mention the TSB says the amount of time needed is 0.5 hours, so i'll see if they'll do it for half their hourly labor rate. Thanks again for sending my the actual TSB it really gave me a lot more information into everything and convinced me a PCM flash is probably the way to go. I'll get it done today.
 

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The dealer minimum charge or diagnostic fee is usually 0.8hr to 1.0 hr. They usually won't go down to 0.5 hr, but it doesn't hurt to ask. Any combined services in addition to the TCM flash may give you some room to barter about price.
If the shop is slow and they really want the work, they can be quite accomodating if it sounds like you aren't interested on the phone. It is the service advisor's job to bring the work in and the technician's job to sell it once it's there. Good luck.
 

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Discussion Starter #9
I called around and the cheapest price I got from 2 dealers was 69.95 for the firmware update and quick learn. I can live with that, glad I checked other places first though. I'll have them do those two things and report back on how it all works out.
 

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$69.95 is an excellent price. My dealer typically charges $99.95 for similar services.
 

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Discussion Starter #11
I have an appointment for tomorrow morning at the dealer to get everything taken care of, they won't garrantee it will work or not since I request the TSB to be done without them doing any tests but who knows how much more that will cost.

Eventually I might break down and just buy a universal professional diagnostic scanner off ebay, one that will perform certain tests on things. I can't stand dealer charging $70-$100 just to plug in their DRB tool, press a few buttons and it's all done, I could easily do that myself with the right tools. A quick learn is just starting the engine, selecting transmission quick learn, applying the brake, putting the car in reverse then drive, all done. People do that everyday in their cars with the exception of pressing buttons on the scantool, but they don't get paid or have to go to college for it.

The cheapest I found that claims to do a quick learn is an Autocom box that plugs into your computer using usb or bluetooth. I have no experience with enhanced diagnostic scanners but this one costs $100 so it will pay for itself fast. I also know I need a PCM update which I doubt any scanner under $1,000 will be able to do, plus you need paid access to sites for the firmware files. But for doing quick learns and much more I think it's the cheapest way to go. I was also looking at an OTC 4000 Enhanced but it seems very outdated and don't know if it will work with the NGC PCMs like the autocom claims to. Just a thought, if anyone has input on this, feel free to reply. Thanks
 

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That Autocom thing is just a OBDII scanner. Your cell phone is just as powerful.

If you want something that works on these cars, you need to invest in an old used DRBIII, a StarScan, or one of the generic Snap-On tools (not quite as good as factory, but very, very close). They are all expensive, but they can actually access the PCM for more than just trouble codes, they can reprogram pinion settings, program the security-chipped keys, and loads of other stuff.

The StarScan (Witech) scanners are some of the most powerful diagnostic tools available. They actually do more than the old DRBIIIs, but with the right software package, emulate them exactly. Older OBDII cars need the DBRIII, newer CANBUS cars need the StarScan.

StarScans work on everything Chrysler made up to 2012MY. 2013's have a newer CANBUS system which is above what the StarScan can handle.

They are expensive, even used, but they can easily pay for themselves. Know someone who needs to adjust the pinion factor for larger tires? You can charge them a small fee and do it with the tool. True, dealer-level diagnostics? Yep, you can do that too. How about somebody who wants a new key programmed? Yep, you can do that too...

Seriously, if you have the money to spend on it, these are worth it...

http://www.ebay.com/itm/Chrysler-Starscan-OEM-Star-Scan-Tool-DRB-III-3-Starmobile-Witech-Dealer-Tool-/181078723388?pt=Motors_Automotive_Tools&hash=item2a29220b3c&vxp=mtr
 

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Sorry, that may have come off a little insulting. People hype up these scanners though, and most of the time they just can't do what they say they can.

https://autocom.se/uploads/file/AppTable_CARS_CDPPro_webb.pdf

According to the manufacturer, your 2003 Stratus isn't even covered. (Now that can't be completly accurate, as your car still uses OBDII for basic diagnostics.)

[EDIT: Found coverage for 2003MY Sebrings. They are the same car (electronically, anyway), so they info listed would apply. The manufacturer states "Generic OBDII" for functions - that's it.]

Anyway, my point is this: Chrysler wanted to make sure that not just anyone could go in and change things in the vehicle, so they encrypted the data in the PCM and hid it out of the way. The OBD codes are only the tip of what is really available in the computer with the right tool.

Not everyone can afford one of these tools - hell, I don't even have one - but there is no substitute for a real, professional grade scanner if you are looking to fully diagnose things. If you want just a good OBDII scanner to check OBDII codes and reset the CEL, look at something like the Innova lines. They are good scanners, with data monitoring capabilities on some models, at a fraction of the cost. No - they won't reprogram your PCM, but they are more handy and reliable than that Autocom thing appears to be...
 

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There are aftermarket scanners that will work, but the expensive ones won't help with the transmission or other systems. Many years ago I bought a used SnapOn MT2500 for $600 and it did 90% of everything a DRB would do. But it was still expensive. At the time I had 4 A604 cars and another with ABS problems so it paid for itself eventually. Whatever replaced the MT2500 is what you'd need from SnapOn and I'd bet it's well over $1k.
 

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Ah very good information. I'm still trying to learn as much as I can about these scanners. I've seen many repair shops with snap-on scanners, they seem to be the way to go. I was looking at the MT2500 but heard it only covers vehicles up to 2000, maybe 2003 with the right cartriages and keys. The cheapest used DRBIII tool on ebay is about $2,500 right now, still much better than $7,00 they were last year. I've also looked into OTC scanners, the newer Pegisys line can reprogram the PCM as well as perform most if not all the actions a DRBIII can, but those are around $1,000 and up in price.

After a while of searching It got me thinking why these cost so much, is it just how the market is or do they really need to because of the hardware they use. Most newer touch screen scanners run a windows xp or ce OS and are basically a handheld tablet which would drive the price up right from the start. This made me lean closer to finding just an interface piece of hardware that plugs into your usb port on a laptop you already own and paid $500 for. I see the same thing happen with the basic ELM327 usb scanner cable I have and the handheld generic OBDII scanners, the price triples when you add the handheld hardware, the basic usb cable can be had for about $12 now. That's where the Autocom CDP was appealing to me, it seemed like the generic next step up in OBD scanners that support enhanced OBD diagnostics, such as activating certain transmission and ABS systems, or so it claims to, without the fancy handheld hardware, just a PC interface and your computer tells it what to do.

Also on another note, I just went to the dealer yesterday and they updated the PCM, they should have done a quick learn too, but the bill didn't say anything about it so I'm not sure. But it shifts just as before except the 4-3 downshift now is much better, you still can slightly feel it but it may still be releaning the CVIs for the underdrive clutches. So I'd say it's fixed, I drove it about 100 miles around town and on the highway yesterday, drives like a new car even though it has almost 200k miles on it. I'm happy, and a special thanks to ImperialCrown for the great advice, that was exactly what it needed.
 

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The cost comes from a couple areas:
1) Truly ruggedized equipment is expensive. Sure you can get a $400 laptop, but a ruggedized hard drive (rotating or flash) can cost almost that much in larger capacities. Same with touch screens and all the other ruggedized gear. How long would the average laptop last in a service bay in a garage? I've worked in the ruggedized industrial computer industry for years and $1k-2k is the going range for a hand held rugged device.
2) Development time. Any cheap scanner (and much of the cheap laptop stuff) only covers the basic OBDII functions. Any that cover OBDI or interface with the advanced systems (transmission, ABS, air bag, body computers). In the case of the OEM, you try to cover the development costs in the price of the equipment. In the aftermarket, you invest time in interfacing or cracking OEM code.
If there was a cheaper system out there, you'd see it in the shops. As it is, the SnapOn options (MT2500 and the newer one) ARE the cheaper options.
 

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Very good points, it seems the basic code readers are geared towards home use, but the professional scanners that have advance capabilities doesn't really have a market in the personal/home use environment, it's all geared towards shops where it gets used everyday in a busy place, who also have quite a bit of cash to put down on something.
I'm glad you shared and explained all this information here, I'll deffinatly be looking into a Snap-On scanner then. Also having a big name behind a product is always a plus, and I'd rather buy cartriages/keys rather than an entire scan tool to do do multiple makes of vehicles, which the MT2500 did just about everything up to 2000.
 

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I think you can find MT2500 cartridges that can go up to 2003, but the cartridges themselves can get very expensive. The updated replacement for the MT2500 is nice too, but it's new enough it is still expensive even used..
 

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Yeah, the MT2500 is good - I have seen them for sale on eBay with all the modules you'd need to handle Mopars up to 2005MY when they switched to CANBUS for less than $1000 several times. Just gotta keep checking in...

Glad you got the issue solved!
 
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