Not feeling good about this.
'01 S40, 185,000 miles and has been a good car.

Bought at 145,000.
Here's the transmission maintenance that I've performed.
Drain / fill transmission with Dex III at 147,000, 150,000, 156,000, 160,000, and 170,000.
Then flush (not power flush) with and change to Mobil 3309 at 173,000.

The reason I switched to 3309 was on recommendations that said the '01 owner's manual was wrong and that it was supposed to list a fluid spec like 3309. Dex III was not supposed to have ever been recommended according to "the experts".

So today the car started to have a "very" hard shift into Reverse. Then when put into Drive and trying to accelerate away, it felt like the brakes were on. Really had to press on the gas to finally get going.

Gosh I hope it's not the transmission. I was hoping to get another 2 years out of this car. But a broken automatic at 185,000 miles is not unusual.

Thinking I may flush back to Dex III tomorrow and cross my fingers.
Thoughts?

Most interesting. The owner's manual says 4 speed, and then gives the gear ratios for 5 speeds? The manual also says DEXIII, but the 5 speed AW50 should be using 3309??

I would go back to DEXIII with a flush and see if that improves things. But that doesn't make logical sense to me.


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My back feels better when I sit in a Volvo seat

Here's more info. and symptoms.
I tried to engage "winter" mode to see if that would make any difference, but the arrow would not illuminate on the instrument cluster. Could hear a noise somewhere when pressing the "w" button but it does not appear to have engaged. For some reason, I think you can't engage winter mode above a certain ambient temperature. It was about 80 F or so at the time. I'll check the manual.

I did row the gearshift back and forth to no avail and the fluid looks great and is at the proper level. Still bright pink and doesn't smell burned at all.

This car is a 2001 1.9T North American delivery with what I've always assumed is a 5 speed (automatic). Shifter indicates P-R-N-D-4-3-L.

Maybe my Dex III drain / fills from 147K to 173K miles (26,000 miles) destroyed the transmission.
Or maybe the 12,000 miles of 3309 spec did?
Or maybe the transmission just has given up after 185,000 miles.

Took it for a ride this morning and here's what happened.

Car sat overnight. Ambient temperature 68 degrees F.
Cold start normally and the CEL comes on - P0600 according to my ScanGauge II.
P0600 comes up as a generic Serial Communication Link Malfunction.
Sitting in the driveway, the transmission acts absolutely normal. Smooth shift into Reverse, smooth shifts into Drive, 4, 3 and L. Creeps forward slowly when letting off the brake and in Drive. Just like usual.

Pull out of the driveway and go up the street. Left it in Drive and it shifts normally through all the gears. Included a few stop and starts and still the transmission is working like it should.

After about 2 miles I come to another stop and I can hear a distinct slight whine coming from under the hood. Shift to Neutral and the whine subsides. Shift back into Drive and the whine starts again and the car is in what I assume is limp mode (appears to be 3rd or 4th gear). I didn't want to try Reverse as that previously resulted in that destructive sounding BANG yesterday. Tried shifting to Low in hopes of being able to start off in 1st gear, but that made no difference. Regardless of where I put the shift lever (in forward gears) the transmission stays in limp mode.

I'm now thinking the problem has something to do with the transmission temperature and that whining sound. I thought the UP arrow is supposed to flash if there is a transmission malfunction, but that hasn't happened yet.

Check this thread:

http://forums.swedespeed.com/showthread.php?198629-2004-v70-p0600-code

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My back feels better when I sit in a Volvo seat

Hold everything! The P0600 is the problem, not the tranny. Seems that once the computer(s) warm up, you are then put into limp home mode due to electronic failure.

Check your battery voltage, it must be at least 12V.

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My back feels better when I sit in a Volvo seat

Thanks for the encouraging words.
I'm thinking along the same lines re. temperature related - not necessarily mechanical. When I drove it this morning, it seemed like usual - normal shifting, no weird noises.
I guess it still could be a transmission issue when it warms up, but there are still things to diagnose.

Fortunately she can use the smokin' '95 854T for now. Gives me an excuse to get back in the 145. Still gathering information and possibilities on the S40. I don't want to jump into any repairs or get rid of the car yet without a good diagnosis.

I guess now I have to figure out what computer(s) may be overheating or causing the issue. Seen a lot of simple broken solder connections that can cause havoc. Thing is, I don't even know where to start. I think Haynes has a electrical diagram.

The 2001 Volvos have more computers than the 145 has fuses!

All of the computers communicate through a central buss computer, which is probably where the problem is. Seems that the heat sinks are not thick enough to absorb all of the heat under the dash. Unfortunately, the dealer just replaces with same old junk at high prices, and then has the gaul to charge for programming it to your car!

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My back feels better when I sit in a Volvo seat

I'm thinking that a dealer repair is pretty much out of the question for this car. Dealer labor charges around here are $120 per hour or so I think. The value is only around $1000 when in "good" condition. Kind of doubt the dealer would be interested in attacking this kind of issue.

If it does turn out to be a mechanical problem caused by use of Dex III, I'll be quite mad since that is the recommended fluid in the owner's manual.

Haynes says the transmission ECU is under the console so that shouldn't be too hard to find.
Not sure what I'll do with it once I find it.

I don't think it is the TCU that is a problem, rather the CEM (central electronic module):

http://xemodex.com/us/product/central-electronic-module-for-volvo-vo-1070-30859699-10-20/

Of course, you would need a really good code reader to be sure.

Before starting the car with a cold engine, try clearing the codes first and see if the p0600 comes back immediately.
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My back feels better when I sit in a Volvo seat

Well, I know what the CEM acronym means now!

This is a good start, but after a quick look (have to get to work) is appears that a lot of CEM questions are about lighting.
Not saying there are no transmission questions, just that I have to keep searching and don't have the time at the moment.

I'll have to ask my daughter if the car has some other electrical issues that I'm not aware of.

Sincere thanks for the help Klaus.

This is going to be a learning curve. You already know about the TCM and ECM. Your car also has a DIM (instrument cluster), ABS module (why they don't have a --M for that), and a little known CEM.

The CEM is nothing but a buss, it routes communication between all of the computer boards. If anything goes wrong with the CEM, the other computers do not get the required info needed to make adjustments to speed, rpm, temperature, etc. Sometimes the DIM is affected, like no speedometer/odometer and when that happens the car will shut down and become road kill.

The problem with the early DIM and CEM is the heat sink is not large enough and diodes melt. It has nothing to do with 'lighting' and everything to with communications.
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My back feels better when I sit in a Volvo seat

You may have nailed it.

Here's the latest...
I found a 125K mile transmission at a local recycler. Price was fair enough that I chose to roll the dice and install it. First time I've removed/replaced a FWD transmission. That's a story in itself as there is not a lot of room under the hood of an early S40.

Fired it up this morning and the EXACT same thing is happening. I just can't believe that both transmissions (my original and the replacement) have the same problem. So that leads me to believe that it's a software issue as you surmised in the first place. Yea, back to the P0600 code.

Also surfed and found a TSB (#197387) but not a lot of details about it. Wish I could find more details about the TSB.

Kind of at a loss at the moment and not ready to "roll" again with the CEM replacement. I wish there was a better way to shade-tree diagnose than just bringing it somewhere. Fortunately we still have a few extra cars to use in the meantime.

Sigh.

Fast forward another month.
SUCCESS!
I believe my nightmare may be over.

It all went back to the no communication problem. But an unlikely culprit.

I ended up sending the car to the dealer for an evaluation as a last resort. I got a call that they spent over an hour or so going through the car and couldn't find the issue. They asked if I wanted to spend any more on it and I said another hour, but that's it.

Next call from the dealer? They think they've got it.
Picked it up yesterday and put about 70 miles on it. Excellent. Just like it's supposed to be.

The problem?
How about the power and communication leads that go into the TCM were pulled out within the TCM connector just far enough that they weren't making contact!
I'm not sure how that could have been other than like that since the car came from the factory.
Myself, a few other Volvo friends, the guys from Re-Volv and even the Volvo tech had that connector on and off the TCM multiple times and never noticed anything amiss. The connector is large and has quite a few wires going into it. They're also harnessed together so they all move as one. Damn near impossible to see.

Regardless, it seems to be working now.
I'll use the car for the next week or two to confirm, but things are looking good.

Thanks again for all the help. I'm glad to keep this thing on the road.

Wow! Not something I would have guessed either. Someone unplugged it at one time and had problems plugging it back in, making the connectors loose.

Good find, a dozen donuts to the mechanic that found that one!!!
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My back feels better when I sit in a Volvo seat