7 Symptoms of a Bad Transmission Control Module (and Replacement Cost)

Last Updated on May 11, 2021

The transmission control module (TCM) is a vital component of any vehicle with an automatic transmission system. Rather than relying on hydraulic or mechanical control over a transmission system, newer vehicles use a transmission control module instead.

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A car’s TCM will likely never need replacing, but if you have a bad transmission control module, immediate replacement (or repair) will be necessary. This module is basically a computer which communicates information to other computer systems within the vehicle.

The purpose of the transmission control module is to help the automatic transmission choose the best gear to be in at any given time. That way, the driving performance and fuel economy will be at the optimal level.

See Also: PCM vs ECU vs ECM vs TCM (What’s the Difference?)

Signs of a Bad Transmission Control Module

The transmission control module can often be found below the cover at the back of the transmission case. It should be just below the engine control module’s position. Sometimes it’s found under the center console in the interior or even under the hood near the battery or inner fender panel.

If you ever have a problem with your transmission control module, you’ll need to have it inspected right away. A bad TCM will spell trouble for your vehicle and your ability to drive it. Fortunately, there are a few basic symptoms that you’ll most likely notice before this happens.

#1 – Check Engine Light

bad-tcm-symptoms

If the Check Engine warning light illuminates on your dashboard, it could mean several things. But if you notice any problems with your shifting in addition to the Check Engine light being on, then it is most likely a problem with your transmission control module or some other component of your transmission system.

In any event, get your vehicle checked out immediately by a mechanic or use your own scan tool to check for any Diagnostic Trouble Codes (DTC). If code P0700 shows up, you may have a problem with your transmission control module.

#2 – Unpredictable Shifting

automatic transmission shifting

Since an automatic transmission system relies on the transmission control module to do the shifting, a bad transmission module will cause incorrect or unintended shifting. This can prove to be anything from an annoyance to causing a serious accident.

For instance, if your car shifts to neutral or any other gear that it normally wouldn’t shift into without warning, then your control module will likely need to be replaced. Otherwise, it will be very dangerous to continue driving.

Unless you have a manual override option in your vehicle (example: paddle shifters), you will need to get your car towed to a repair shop and have the module replaced.

#3 – Problems Shifting Into Higher Gears

high RPM tachometer

As you gradually increase speed, your transmission should correctly shift into higher gears at the correct time. When this doesn’t happen, you’ll notice that your engine’s RPM simply keeps increasing instead of slightly dropping an upshift occurs.

Because each gear has a maximum speed it can go to, you may never reach your intended speed if the faulty TCM refuses to shift to a higher gear.

#4 – Problems Downshifting

can't downshift

This is similar as above but in reverse order. Maybe you need to pass a slow moving vehicle and your transmission fails to shift into a lower gear when you mash the gas pedal to help you accelerate.

Or you’re cruising down the freeway and take an off-ramp, your transmission should gradually be going into lower gears as your speed decreases. At a stop, an automatic transmission should be in first gear so it’s ready to go when you need to start moving again.

If your transmission control module is bad, you may still be in a high gear as you’re coming to a stop. When it’s time to start moving again, you’re in a too high a gear for proper acceleration which may even prevent you from moving at all.

#5 – Stuck in the Same Gear

tire noise

This usually presents itself as being either stuck in neutral or first gear. The transmission simply will not shift and you either won’t be going anywhere (stuck in neutral) or you’ll be limited by the maximum speed of first gear.

#6 – Delayed Shifting

reasons and causes of car not accelerating

The speed of your vehicle relies on cycling to various gears at the appropriate timing. If you have a bad transmission control module, then it will cycle to next gear too slowly.

This will impact your acceleration, causing you to lose speed rather than picking up speed. When you approach a hill, the shifting performance will be even worse.

Worst case is when you’re attempting to pass a slower vehicle on a 2-lane road and your vehicle refuses to downshift immediately so you have more torque available to make a quick pass.

#7 – Poor Fuel Economy

poor gas mileage

Problems with your transmission system usually result in bad fuel economy. An automatic transmission is designed for optimal gear selection and timing to provide you with the best possible fuel economy.

If you have a transmission control module that’s bad and affects this timing, then your engine will end up working harder than usual. This means it will consume more fuel than usual, causing you to spend more money at the gas pump.

Replacement Cost

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transmission control module replacement cost

The replacement cost of a transmission control module will be anywhere from $500 to $900. You can expect the parts costs to be around $450 to $700 while the labor costs will be around $50 to $200.

Of course, you can order a new TCM online and ask a mechanic what their hourly labor rates are. However, most of the cost for this replacement job goes toward the parts cost itself and it can vary greatly by car manufacturer. You can expect taxes and fees to be added to the total cost as well.

Repair Cost

Another option is to repair your TCM. The transmission control module repair cost will in almost all cases be lower than replacing with a new module. On average, expect to pay around $300 to repair your transmission control module.

While most TCM repair businesses will offer a warranty of some sort, it does pose a bit more risk if the repair is not done right.

Also, you may need to ship your bad TCM to a non-local location so if you can’t afford not having your vehicle for a few days, replacement would be the fastest method.

 

109 thoughts on “7 Symptoms of a Bad Transmission Control Module (and Replacement Cost)”

  1. I took my 2012 Kia Sorento in to a transmission shop with code P0700, they switched a grounding wire, a pin, and later a sensor, the downshifting problem is still not fixed, now they said it’s a code reset that only a Kia dealership can perform, is this the same as the TCM, or something different.

    Reply
  2. Hi
    I have a mazda 3 2014
    I was driving and the engine light came up and the car got slower i took it to mechanic and they said it has TCM problem which is gonna cost alot of money to replace it . After checking it the next day everything seems normal no engine light on , does it mean i don’t have to replace the TCM

    Reply
    • When the issue first happened, the car may have switched into limp mode. You likely do have an issue with the TCM if that’s what the mechanic found after scanning for codes. Sometimes a code will temporarily clear itself but there’s a good chance it will occur again. Keep an eye on it.

      Reply
  3. Hi I have a Volvo S60 Auto D5 2004 model, the codes is tcm-0002 and tcm-0115 do I have to replace the solenoids or what could be the problem.pls help

    Reply
  4. I have Nissan xtrail 2.0 4wd from malaysia …. when i put it in D the engine engage like its in gear but the car wont accelarate…. i try to put in R or other gear is same… the engine engage like in gear but no accelaration… i try to pull out socket in tcm and its same.. the engine still engage like in gear but no accelaration…. if that mean i need a new tcm?

    Reply
  5. i have unusual problem,while driving 1997 ck1500 (new engine and trans from GM)
    as I am driving in any gear it jerks and at times jerks hard,all new parts on engine when i replaced it.( no codes,and scanner says all is well,4L60E trans)
    had it to a gm dealer and they dont know,i have had it other repair places,all come up with same ,cant figure it out.
    i pull a car trailer with a car in it to shows,and dont seem to jerk at all.
    i need help finding this problem,taking a long trip ,

    Reply
  6. Hi

    I have a Subaru Forester 2010 with a 2.5l engine and automatic transmission. It starts ok , engage gear without problem but hesitate when I ask for accelaration.

    From a dead start, at normal temperature, the engine does not seems to have the power to move the vehicule and it finaly does it by gradually accepting to accelerate. And to acheive that, I have to lightly play with the gaz pedal. Accelaration feels stronger as it gets closer to 3,000 rpm. Riding between 35 and 50 mph seems to be the ‘safe’ region. If I try to go faster, the transmission downshifts, sometimes 2 gears, but the vehicule won’t go any faster, just rev to the limiter! Like a slipping clutch on a manual transmission.

    Lately, I had 2 bad situations :
    – once, the engine sudenly slowed down from 30 mph to around 3 mph for a thousand feet before regaining life and
    – at another time, it simply shut down; I had to coast to the side of the street, put the transmission on Park and restart the engine to continue my trip (I was almost at home).

    When the vehicule has been run for let say 10-15 min, it begins to emit a harsh low sound, telling that it’s not happy at all to ride.

    The code say TCM but I have a hard time believing that this module can produce ALL of those symptoms. On a Forester, the dealer is asking 1650$ for the module and say that it might not be the only problem!

    I first thaught that it was a faulty accelarator sensor but I have no way to diagnose this other than the symptoms.

    What would be your take on that?

    Thanks

    Reply
    • It definitely sounds like a transmission issue. Hard to say if it’s just the TCM at fault or if the TCM is indicating there is a different problem, without knowing the code.

      Reply
  7. I have a 2015 GMC Yukon XL.

    When I went to get in to leave from somewhere the other day, I backed up, put it in drive and nothing. Transmission completely stopped working. I only have reverse. Motor is strong, lots of power when reversing. No symptoms or signs before this happened, had drove it on a 4 hour trip a week prior without issue.

    Check engine light came on, I have codes: P0700, U0100,U0101 and U0073.

    No flakes in the fluid and I fired it up today and the check engine light is now off. I haven’t tried to put it in gear to drive though.

    Your response is greatly appreciated!

    Reply
    • How strange. It sounds like the modules are having a hard time talking to each other. Check the wiring harnesses near the ECU and TCU if you know where these are. Look for any obvious signs of holes or breaks in the wiring. Sometimes rodents will actually chew through wires.

      If you don’t see anything, see if there is a technical service bulletin (TSB) or recall out for an issue with the ECU or TCU on your vehicle. These modules may also be called ECM, TCU, TCM, or PCM (different manufacturers use slightly different acronyms for the engine and transmission computers).

      Consider bringing your vehicle into the dealership if it’s still under warranty.

      Reply
  8. Could a bad TCM system cause my 2003 Dodge Ram 1500 to shut off while stopped at red lights and stop signs? It usually starts up fine and drives good for about 5-10 minutes, but after driving for a while and stopping my truck starts to shut off.

    Reply
    • I would expect a check engine light if the TCM failed, not an engine stall. A failed or failing TCM may cause the vehicle to run in limp mode. This often will mean the vehicle has reduced power and will be stuck in one or two gears.

      Reply
  9. 2002 excursion. Tranny stop functions overnight. Was scanned a couple weeks ago and clutch sensor popped up. This AM putting it in gear and nothing happens until high rev

    Reply
    • I have a 2009 Chevy Silverado 4.8L 4×4 that popped up service stabilitrak while I was sitting in a fast food restaurant drive thru. It is in limp mode now slowly accelerating from take of & will not shift passed 2nd or 3rd. OBD2 scanner says lost communication with TCM. Also my digital transmission temp guage – – – instead of telling me its temp. My reverse will not come on in reverse but will when its in park & I turn truck off. My door lock periodically lock & unlock on their own. I changed my throttle body about 6-12 months ago & haven’t had any problems or throttle codes pop up since. PLZ HELP!

      Reply
      • Sounds like you have an electrical issue that’s affecting a few things. Check all your ground straps to make sure they are clean and tight, with no corrosion. Check that the battery terminals are also tight and free of corrosion.

        Reply
  10. Battery is good & I even added a ground but still no luck. I also changed the brake pedal switch thinking that might be it because when I press the brake & let of it there is a loud clicking noise but still no luck

    Reply
  11. All of these issues happen in my 2004 Mazda 6i 2.4L . We connected an OBD2 reader and it didnt throw any codes. Is this normal for the TCM?

    Reply
    • Sometimes transmission issues won’t necessarily throw a code for the OBD2 reader.

      OBD2 is only designed to detect certain kinds of failures, such as an interrupted communication between the TCM and ECM, failure of emissions components, and misfires. If it is a mechanical issue with the transmission, you may experience some of these symptoms with no OBD2 code.

      Reply
  12. Kindly help
    I have Ford Fiesta currently having transmission malfunction.
    Run DTC and found these codes:
    P0700 – Transmission Control System Malfunction
    P287A – Clutch “B” Stuck Engaged
    P2872 – Clutch “A” Stuck Engaged
    P2701 – Transm friction element B, apply time – range/performance problem
    P0882 – TCM – power input signal low
    P07A5 – Transm friction element B, stuck on
    P07A4 – Transm friction element B, performance or stuck off
    P0702 – Transm Control System electrical
    P06B8 – internal control module, non-volatile memory – error

    Reply
    • Wow, that’s a lot of codes. The good news is when you see so many codes, you often have an issue that throws many codes at once.

      Start with the transmission control module. Visually inspect the TCM for any issues with the wiring. I would also give the ECU a look since the two systems need to be able to talk to each other.

      Once the visual inspection checks out, you can try testing with a multimeter to make sure the systems are able to communicate as expected. To do this, you will need a factory service manual with a wiring diagram.

      If you’re not comfortable with this level of electrical troubleshooting (which I totally understand), it would be best to take your vehicle to a mechanic and pay their diagnostic fee. They should figure out the root cause of the problem and give you an estimate for the cost of the repair.

      That last code (P06B8 – internal control module, non-volatile memory – error) sounds to me like the TCM has gone bad. Non-volatile memory is permanent storage, like the hard drive in your computer. If the TCM has an issue with its permanent storage, its programming could become corrupted and cause the unit to malfunction.

      Reply
  13. I have a 2007 Chevy Cobalt. I’ve been having issues with the TCM for a year now. Every now and then, Power Steering appears on my DIC, and my car becomes harder to steer. We’ve replaced the Transmission Control Module and replaced the disintegrating wires so we thought the issue was fixed. A few weeks ago, I was driving and had this problem upon startup again. Once I got on the road and shifted into 3rd gear, something in the car kicked and suddenly my speedometer came back on and everything went back to normal as I was driving. So my question is: can a TCM come back online at random or is there something I’m missing?

    Reply
    • If there’s a bad ground or disintegrating wires, the system(s) which share that circuit may work intermittently, yes.

      However, I don’t think the TCM would be related to your power steering issue. Check a wiring diagram to be sure, but it seems like you have two separate issues going on.

      Reply
  14. You should always research the code meaning & diagnostic steps first. I wonder how many people reading this replaced the TCM & still had the same issues or more.

    Having a P0700 does not necessarily mean you have TCM problem. It is an OBD2 generic informational code from the ECM telling you there are trans-related codes stored in the TCM & that you need to switch into that module for more codes.

    After 45+ years of doing transmissions, TCM failure is one of the least likely things to fail in most vehicles. There are a couple of models in which TCM issues are common but very, very few. But even then doing the proper diagnostics is the most critical step.

    Vehicles built in the last 20 years usually have more than one control module for different areas. The ECM has codes that direct you to those modules when needed. P0700 is one of them.

    Codes are to a vehicle like blood pressure is to a human. It’s just a number that tells you a particular circuit has a problem, not the failed part. Do you need a couple of aspirin or major surgery? Just because you have a solenoid code, it doesn’t mean it’s always a bad solenoid. A broken wire or corroded connection in a wiring circuit can set the same code as a DTC referenced part. That said, sometimes it’s faster & cheaper to first throw a part at it than spending time going through the other diagnostic steps.

    The bottom line is if you are not familiar with what DTC means or the steps to check it, a wrench isn’t the first thing you grab, it is first researching it.

    Reply
  15. I have a problem with a 2005 Jeep Grand Cherokee 5.7L hemi I just bought. It keeps saying transmission over temp and it seems we’ve fixed everything we can except the Tcm. We have replaced the temperature sensor, torque converter, and the transmission cooler. It doesn’t seem to actually be overheating because the fluid is bright red and doesn’t smell burnt at all. Would anyone know what’s wrong with it?

    Reply
    • I’m reading that lots of people have had to replace their PCM to address this issue. You’ll want to do some testing before replacing this part to make sure the PCM is actually the root cause, because it’s an expensive part. I recommend doing a bit of reading on the Jeep forums. Then, you can make an educated decision for yourself on what route you would like to take.

      Reply
  16. My Allison is attached to a 525 Cat in a 2007 Coach (Mfg Year 2006). I’ve had the 6 speed world Allison in 2 others, attached to a 350+/- and a 400 Cummins. In those, the downshifting was not as noticeable, that I can recall, that slows down this big beast on gradual down slopes vs maintaining speed or increasing, leaving the speed choice to MY ENGINE BRAKE = ME! I need this to STOP slowing me down as I need the MPG to make up for the 1.5mpg hill climbs (for example).

    Reply
  17. I have X-Trial 2014 T32 Ti Petrol 4WD model and recently I am experiencing a strange issue. While flooring the accelerator between 35kms to 55 Kms, it shudders with sound. When I drive with light acceleration, it doesn’t make any issues. Is this Transmission issue ? When I checked with ODB diagnostic scanner, it shows U1000 error ,unable to connect to TCM. Can you please reply when you get a chance ?
    Thanks,
    A Jose

    Reply
    • What does it sound like? Perhaps it’s the TCM, but it could also be a grounding or wiring issue that’s interrupting the signal between the ECU and TCM. You’ll have to do a bit of electrical diagnostic work to know for sure.

      Reply
  18. 2015 Ford Focus. Transmission problems since l purchased the vehicle, brand new. Several repair/replacements to the clutch and the latest is a TCM replacement. Ford has covered the cost but l fear a complete system failure is imminent. Do not purchase this model of used vehicle.

    Reply
  19. Hello what could be the problem when 2018 Gmc. Transmission is put in park after engine turn off my truck and to roll backwards this is a first time problem and no other problems with this transmission. Thanks

    Reply
    • It sounds like the parking pawl inside the transmission might be broken. You will probably have to drop the transmission to have it serviced. It would be best to consult with a transmission shop for more information and a quote.

      Reply
  20. I have a 2000 chevy silverado 4×4 changed transmission in myself with a used trans out of another truck a2001 I bought but after changing trans my abs light is on parking brake light no cruise control no speedometer won’t shift only got first and second gear manually shifting. No 3rd or 4th gear at all and it worked and shifted just fine in the other truck but the speedometer worked to in it. And threw no output speed sensor replaced both of them and still have nothing. What could it be?

    Reply
    • Check all your ground straps, make sure you didn’t miss a ground somewhere. Double check that the electronics are the same between both vehicles. There may be a slight difference in wiring that is making the two transmissions incompatible. Both trucks are 4×4, right?

      Reply
  21. I’m have problems with my 01 Acura TL the car will start up with no problem an I can drive for a few but when I get to 35 40 mph it starts to slow down by it’s self an when I go to press the gas it seem like it’s in neutral an the the engine would get a lil louder then it won’t move at all an when it does that I have to put the car in park shut it off wait a couple of minutes start it up. Again an it will drive can someone plz let me know if it’s the transmission or a part I need

    Reply
    • Are there any check engine lights? It could be going into limp mode for some reason. If it’s not that, it’ll be hard to say what the root cause is without someone doing a bit of diagnostics on your car.

      Reply
  22. Hi. I have a 2012 Peugeot 508 diesel. The auto trans specialist suggested I needed to see if Peugeot have come up with a Transmission Control Module patch, like Vovo have. Do you know?

    Reply

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