2008 S40 2.4i automatic transmission. I just purchased the car 2 weeks ago and doesn't seem like anything was wrong for a whole week or so. Then suddenly I got no power at all. I hooked up a scanner and found the codes P0700 and P0811 which translates to P700 is Transmission Control Malfunction and P0811 is Excessive Clutch Slippage. Power the car down and start up the car drives fine, then I cleared the code. Then 2 days later I had the scanner hooked up and monitoring it, the P0811 shows up 1st, no issues with power yet so I continue to drive it without stopping and going. Recently it's been very hot like 93-97F I suspect that this happens when the car gets hot and the TF fluids are not working. Cleared the code and keep on driving. Then recently it went to P811 again and then P0700 which put the car in limp mode and was fine after cooling it down and starting it up and cleared code again. I've driven it around and never felt there was any slippage or shifting problems at all. So I'm suspecting this could be some kind of lack of transmission fluid or wrong type was used.

So I decide to have AAMCO nearby diagnose it. I told the mechanic the same story above, maybe I need to do a full ATF flush to get whatever gunk out that could be blocking the fluid from exchanging with the radiator. He came back to me 3 days later saying the TCM is bad. He said the transmission is fine since the previous owner had replaced the transaxel and the transmission shift solenoid. But the TCM is bad and he wants $1800 to fix it.

I think he's BSing me here, since I had watched the OBD scanner and it always pops up P0811 1st which is the excessive slippage code. Then the P0700 Transmission Control Malfunction show. He says the TCM is malfunctioning so it's not communicating correctly. From my computer knowledge, I don't think a TCM failure would cause this problem, if it malfunctioned I would get the P0811 code right away.

Because the car behaves fine for like 70-100miles before the P0811 pops up. I had the OBD software monitor and it showed that I've driven 164 miles before the P0811 showed up.

Anybody have any experience or insights? I am about to do a complete ATF flush and changing of the filter and see if that helps.

 

With almost any auto tranny issue, the prudent thing to do is to do a fluid drain-and-fill. It's always quite possible that may fix the issue, if only by getting the level right. Do some research - don't try to measure the fluid level - Volvo designed it so that's nearly impossible. Instead, you just drain the fluid, then add 3 or 4 quarts (forget which) and call it a day. Swapping out the solenoids isn't a huge or expensive DIY either (I made a youtube video showing how it's done, FYI).

OTOH, I would suggest doing more research on that 0700 code... it could be a "TCM only error", which could mean your mech is right (hey, it could happen).

 

Unfortunately - now you know why the car was for sale - Sorry

 

Well, if he's right the TCM replace is not as expensive as a whole transmission replace. I can try to pop out the TCM, clean it, and then reseat it back like old Nintendo Game carts. I personally don't think TCM solid state components can go bad unless there's a defect in them. The car has over 125k mi so it made it this far with the same TCM unit. The car is fine when I ran it for awhile then it shows up after many miles. Will have to spend some time and see if these attempts will cure the problem.

 

Got the car rather cheap, before I bought it I put the OBD scanner on it. The MIL if off which indicates there's no pending issues and it wasn't reset and it takes atleast 130 miles for MIL to go off if the seller did clear the codes. He could have driven it very slowly and gently to not have any issues but if the TCM was bad, it wouldn't matter how slow he drives it the computer would have errors sooner or later.

 

An Ammco generic scanner is not going to give you the same amount of information as the factory scanner. So you should consider having someone with the Volvo Factory service manual/diagnostics look at it. Someone with 2014d VIDA, a VIDA subscription or a Volvo dealer, before you spend any more money trying things that probably will not fix it - you might be needing those funds to purchase a different car.

If it turns out you do need to replace you TCM - Xemodex might be able to help you. They list a repair service for most other Volvo TCMs (for ~$500) - but do not mention a S40. They usually want to know what Volvo codes are stored in the units they are fixing (easily retrieved with the free/stolen and hacked 2014d version of VIDA)
https://xemodex.com/us/product/trans...9480761-00-22/

 

I don't trust these Ammco places anymore. The opinion he gave me doesn't seem to reflect what I've experienced. I've driven the car for 3 days since getting it back and the code hasn't appeared yet since I've only made short trips. If the TCM is defective it should gave that code pretty soon. I'm gonna try the drain and replace fluid then get to the TCM and remove it then the clean the contacts to see if it fixes it and will update this post.

Thanks for the link, if nothing else fixes it will send it in and have Xemodex give me a working unit.

 

Xemodex can test and determine if there really is something wrong before replacement for a fee less than the replacement cost. (If they service a s40 TCM)

 

start with cleaning the connector contacts at the TCM. My S40 was having some odd shifting behavior that was fixed by cleaning up the TCM contacts - also check and clean any ground wire contacts if you can and go from there.

 

I just joined in order to reply to this thread. I have the exact same issues, seems to occur mainly on backroads with lots of shifting between 4th and 5th. Vida pointed me to a lockup solenoid, so I've replaced that and done a couple drain and fills in the process. I've cleaned the cem, ecm, tcm contacts. None of that solved issue. Right now I plan on doing a complete fluid drain, since the previous ones only took out 4 quarts at a time. I also plan on doing transmission filter. and double triple quadruple check hot levels when im done. If that doesn't cure it, my next plan of action is probably to replace the torque converter ..... depending on what a shop is going to charge.

 

not sure how replacing the torque converter will influence shifting between 4/5 gear.

Now that you did your cleaning/maintenance have you rescanned for codes? there's quite a few things that will influence when the car is supposed to shift - engine vacuum, throttle position, speed sensor reading, ECM instructions etc.

If you are to the point of considering having a shop pull the tranny, I'm +1 with hoonk on the analysis approach. Before manning the lift, I'd invest the $150 to have a VIDA equipped tech (ie a dealer) do a full diagnostic check using factory tools and procedures.

Also if you do a full flush, double check to make sure you have the correct fluid type for your model/year/transmission

 

Torque converter failing wouldn't cause slipping gears? Anyways, checked my fluid when I got home after a hour drive. Checked it hot while running, looks low.... going to add a quart tonight, see if any change. Plan on doing filter and full fluid change in the next week or 2.

 

The torque converter doesn't cause "slipping gears", but if it's coming in and out of lock-up mode, it's going to feel like it.

Here's the best info I could find on getting the fluid level correct (other than the great advice I got that if you do a drain-and-fill, pouring in four quarts will put the fluid at the right level - I never had any problem with that option).

Here's a link to a thread on the subject that might give you some helpful info...

https://www.matthewsvolvosite.com/fo...hp?f=9&t=81911

 

I changed the lockup solenoid, that was the path vida led me down. Did the drain and add 4 quarts twice during that process. When the issue happens, i barely notice any change, but tranny warning light comes on and goes into limp mode. Dipstick is a pain to get to on 2008 s40 2.4i, but not impossible. I'm convinced I'm a quart low and fluid is somewhat dirty. Going to add a quart, and order 1 to replace. See if any improvement tomorrow, usually throws code multiple times on this particular road. Regardless, going to completely replace fluid and filter soon. If still nothing, i hate to say it but i think its the torque converter. Seems more likely that low fluid is probably the culprit. Will update with results.

 

This is a total shot in the dark, but you might try a tube of LubeGard Shudder Fixx (sic). It's specifically for torque converters, though primarily to cure the shudder issues. And I've had really great luck with the LubeGard Platinum tranny fluid additive, though it didn't do anything for my V50 (it needed solenoids - but I've helped a couple other folks get their misbehaving trannies working like new with the stuff). FWIW, I am very skeptical of most "snake oil" products, but do often recommend these (no incentive to do so, other than I've had good luck with them).

 

Added a quart, no change in behavior. Still plan on changing it out. Hot level looks good. One thing I failed to mention is the issue does not present itself if I can keep the car in cruise control. Issue happens in Drive and also in manual mode. My gut has had me feeling like it is an electrical issue, or maybe something with tcm? Will try scanning with vida this weekend and get some more info. I know the generic code is p0811 for transmission and it throws engine code, but forgot what that is off the top of my head.

 

Another shot in the dark, but I'm betting that the "downshift protocol" uses throttle position as an input, and chances are your cruise control is gentler on the skinny pedal than you are. If your accelerator pedal sender is flaky, and has a "dead zone", normal movement with your foot could send info to the tranny to cause it to downshift (though it might also cause the engine to want to surge). Scanning the codes might point out other possibilities...

 

that makes sense, I was racking my brain on the drive home trying to come up with a sensor that would send different signals based on being in cruise or not.

 

Yeah, I geek out about stuff like that. Using the Torque Pro app, a Bluetooth OBD "dongle", and my 'droid phone, I set up a custom dashboard that I used to monitor all kinds of data when I'm road tripping. One of those things was the throttle position, and it's pretty clear that the cruise control has a much "lighter touch" than my own right foot. For all I know (usually not much) the cruise control might not even move the accelerator pedal (and sender) to set the speed - I've had so many cars, I forget whether or not the pedal moved in cruise control (it does on some of the cars I've owned). If it doesn't move it, then I'd say you're 98% likely to fix the problem with a new accelerator pedal / sending unit (about $50 delivered for a used eBay example).

FWIW, here's a screen shot for the "dashboard" I set up for my Audi A3...

 

I think i'm going to steal your torque display. I've had that app for a while, but i don't utilize it as much as i should. Right now i just use it to reset the codes on the fly. I know that's not the safest thing to do, but I'm not trying to pull over on some PA backroad at 6 in the morning. Also about to order a new pedal w/sensor. It makes perfect sense, when I got this car it surged a couple times while braking for stop signs. I chalked it up to my boot catching the pedal and havent had the problem since, but occasionally the acceleration does feel a little erratic. Usually sluggish. I also know I've kind of hijacked this post, I hope original poster still follows. I've seen the issue posted a few times and have posted myself in several FB volvo groups with no resolution. Was chatting with a volvo tech about it for a bit. It's on the verge of becoming my white whale. lol