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

Last Updated on June 14, 2022

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.

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.

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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.

Related: 4 Bad Neutral Safety Switch Symptoms

#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.

See Also: Code U0100

#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

Best places to order parts?  See: 19 Best Online Auto Parts Stores

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.

Read Also: Body Control Module Replacement Cost

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.

 

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

  1. 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
  2. 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
  3. 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
  4. 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
  5. I have 2010 Dodge Journey. First code showed overdrive shift solenoid so we replaced that. We also did a flush of the trans fluids and still won’t shift out of first gear. I was told it needs the PCM replaced. Is this possibly true?

    Reply
  6. I have a 2014 ford focus and for about a week now , it seems after it gets going and the engine has warmed up if I stop at a store or something come back to the car I put it in reverse and it just sets there and will not back up , after it sits awhile and cools down it will go in reverse and back up , at first the check engine light isn’t on , but when the problem starts it comes on,, if I come to a stop it jerks , but goes and the rpms are higher , when it shifts it acts like it doesn’t want to go but does , it seems like it never gets into the highest gear ,, and runs at a higher rpm ,, after I get home and it sits for a while or over night , the next time I start it everything is fine until runs awhile and same problems,, what could be the cause ? Thanks so much

    Reply
  7. Hello, i can not go passed 50 mpr. Engine revs and becomes louder, humming noise like it has the power but can not go. Difficult to accelerate. Can not go over 3000 rpm. Seems like – reduced engine power, lower rpm and stuck gear. no check engine light. having reduced engine power , lower rpm. Can not go faster than 50 miles, seems to hard engine is struggling and starts to rev.

    Reply
    • I’m not sure, you’ll have to start doing some diagnostic work to narrow down the problem. Check for vacuum leaks, do a fuel pressure test, check spark plugs and wires to make sure they are operating correctly. Also check your engine air filter to make sure that isn’t too dirty.

      Reply
  8. 1997 Ford Fairlane Ghia 5 litre trans want change out if 3 then all gears come good .when playing up there’s a clicking noise under dash when this happens had trans serviced all good all servo,s checked out good no codes come up,is it possible trans computer faulty .cheers for any help

    Reply
  9. I have a 2014 Ford Focus, took it in and it was the transmission control Module it was repaired and four days later it went out again dash states transmission fault check now. Why would it do that. It was serviced at a Ford dealership

    Reply
  10. I have a 2008 gmc canyon going down the road my indicator light will go from drive to park to 1st back to drive the truck will shift up n down and hang up in 3rd and my speedometer will quit working

    Reply
  11. I have a 2010 Chrysler Sebring. It’s been sitting for almost a year after getting another transmission. I drive it’s fine until I goto stop then it sounds or actually does die. Now my gear shift won’t move out of park without me having to use a screwdriver to move the pink thing over while moving my gear shift at the same time. Can replacing my gear shift fix the whole problem?

    Reply
      • 04 tahoe 5.3L engine 4l60e transmission won’t go into 3rd or 4th gear and revs until 60mph and then kicks in overdrive but never downshift it switches between 1st and 2nd no problems also goes into reverse no issues

        Reply
        • My jeep wrangler is doing almost the same but mine its only forth gear and reverse which are working and 123 and 5 do not work?

        • Hi Rob,
          I recently had my 4l60e transmission changed out with a used one.The vehicle is a 2004 Chevy Silverado 1500 4wd 6.0 ltr. engine.I had it replaced because the old one only shifted into 1st and 2nd fine.Whn it hit 3rd it tried but no deal just slippage.Now this used tranny seems to have put my truck in limp mode.Im not sure but I think it stays in third.No reverse,Just third park and neutral.When I step on the gas it bogs down and get some backfiring.Itsvvey frustrating.The guy that replaced it swears that it is a really good tranny.Ive replaced shift solenoids,Oxygen sensors,Shift cable,Shift cable,mass Air flow sensor,BTSI Interlock solenoid,and a few other things like spark plugs,Wires,etc.Still same problem.Am I frustrated? You don’t want to know.Tell me is possible it’s the TCM.Hope it ain’t the tranny.Because I got ripped off by someone I thought was a friend.Its caused me alot of problems in my business.I am desperate to get this over and running out of money.My life is in turmoil.

  12. My Ssanyong Tivoli 2019AT Sport lost the function of its reverse cam, light and buzzer. Fuses, bulb and relays are OK. The car was reversing fine, it was the reversing light,cam and buzzer thats gone. Could the TCM be the problem? Pls. Help…

    Reply
  13. Is it possible that my TCM or tcu is out if my car reverses fine won’t go into gear in automatic mode but is in limp mode in manual

    Reply
  14. My Honda slows down when I step on the gas. I noticed this since the past few days after I went to my Aunt’s.

    Could this be a problem with the transmission control module?

    The check engine light isn’t showing yet.

    Reply
    • I know the check engine light isn’t currently on, but do you have any codes saved in the ECU’s memory? Sometimes that will happen even if the check engine light is off.

      I don’t know if the problem is with the transmission control module or not. You’ll have to do a bit of troubleshooting to narrow down the problem. Do you notice any bogging, surging, or misfires when you step on the gas? What does it do when you push the gas a little bit? What does it do when you step on the gas all the way to the floor?

      Reply
  15. When I push on the gas it goes to 3000 RPMs and it just lose power from there it won’t go past 3,000 RPMs and it won’t go past 35 miles per hour

    Reply
  16. I have a Nissan X-Trail 2WD (2005). When travelling at highway speeds, everything works fine and vehicle performs excellently. However, when travelling at low speeds, for example, following slow-moving traffic or especially when climbing a hill (engine revs below 2), then it does not downshift at the appropriate time, and vehicle looses speed, until either I pump the accelerator to force a gear change, or the speed falls below a certain threshold and then it will down-shift.

    This condition only happens after the vehicle has warmed up (driving for a bit), but does not do it while cold (for some reason).
    I have flushed the transmission on multiple occasions (on recommendation), but no luck.

    Also, while trying to get a reading using a scanner, once the engine warms up, the scanner loses contract with the TCM, and does not provide any relevant readings.

    There are no warning lights or diagnostic codes being received, with the exception of a P0134: O2 Sensor which I suspect may not be directly related.

    Reply
  17. I have a 2007 mustang 4.0 v6 automatic. It works fine in rev. But when I put it In drive it doesn’t do any thing
    The I put it in first or third,I can change gear. Then after it takes off I’ll put it in regular drive and it works. But my rpm speeds goes to 3 or 4 without it switching from 1st gear to 2nd gear,then it jerks into gear

    Reply
  18. I have a 2005 GMC C5500 and I just had the Neutral Safety Switch Replaced because it wouldn’t shift to higher gear and that fixed the problem temporary, now as I start driving my truck goes into either neutral or would shift back to park on its own. Do you think that is bad TCM or could it be something else.

    Reply
  19. I have a 2021 Fiat 500X Sport. I took it to my authorized deal under warranty bc I was given a warning ticket for speeding and according to my speedometer I was driving within the posted speed limit. I also noticed I was getting horrible fuel mileage. Fast-forward to 30 days later I was told that the factory programmed my car for the wrong diameter size tire that was causing a higher rate of speed and they are also going to replace the transmission module. Would either one of this issues effect the milage? My odometer is reading approx 7700 and I estimate that it should be closer to 5000 miles.

    Reply
  20. I have a 2006 Chevy Impala. I had the alternator changed and when I drove it after, it went 2-3 miles and all of a sudden had trouble shifting gears. Seems to be stuck in a low gear, tach moves, but car does not. Never had any transmission trouble until this. Any thoughts

    Reply

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