5 Common Signs Of Allison Transmission Going Out
Most car owners overestimate the lifespan of their Allison Transmissions. They only visit the mechanic store when there’s nothing to fix.
But over the years of dealing with transmission issues, I can tell you some signs of Allison transmission going out.
- Delayed response from your car
- Hearing unusual sounds while starting or accelerating
- A strange odor
- Check Engine Light Turned On
- Difficulty To Shift Gears
The signs are pretty similar for Allison 2000, 3000 and even the newer series. So, no matter which version of Allison Transmission you have in your vehicle, these crucial failing signs will be relevant. Take a look.
Troubleshooting Allison Transmission Is Going Out problems
According to my experience, the valve body, shift solenoid, and torque converter are the common transmission parts that cause issues. It can be simple wear and tear or overheating damaging the internal parts.
No matter what it is, you will definitely see one of the five symptoms I have listed below. Have a look.
#1- Check Engine Light Turned On
An illuminated transmission light on the dashboard is not that serious. It usually indicates the fluid level is low and needs to be refilled.
However, the issue becomes serious when the check engine light indicating a transmission failure gets turned on too frequently. That’s how I usually become sure the TCM (transmission control module) has given up. Either it’s damaged or expired. In both cases, replacing the TCM is an ideal solution.
But to be entirely sure, you can use the OBD-2 scanner along with my intuition. Here are some codes that indicate the exact error with the Allison Transmission unit.
- P0700
If you see this code popping up, the transmission control module might have failed. One interesting fact about the P0700 code is that it prevents the “check engine light” from responding to the transmission issue.
That’s because TCM is normally responsible for delivering this information. So, if you don’t see the lights coming up and the scanner reads P0700 error, it’s definitely a transmission control module malfunction.
- P0750 to P0770
Any error code between P0750 to P0770 indicates a transmission solenoid failure. That’s why the fluid flow is feeling resistant. Different codes within this range represent different gears. That way, you know which shift solenoid (specifically) is having issues.
Note: Code P0218 also points toward a transmission error: overheating. But it can be easily fixed by a quick refill. That’s why it’s not listed above.
#2- Difficulty To Shift Gears
Difficulty in shifting gears is just another name for delayed engagement. The vehicle slips when you try to accelerate the car and shift gears. Even if it revs just fine, you still don’t see the gears engaging. That’s how you become sure the Allison Transmission is not doing well.
Especially if you are using the automated version, you will face allison transmission shift selector problems more often. According to my experience, it’s due to a low or bad transmission fluid most of the time.
Car owners usually get very scared thinking there’s any technical damage within the Transmission unit. However, all I do is check the fluid health and level and change it if needed. That’s how easy it is.
Low fluid level affects the transmission’s functions by overheating and wearing important metal components.
There can be another reason as well. If the shift solenoid that controls the flow of transmission fluid becomes inefficient, you will still notice the vehicle slipping.
Here is how you can check the transmission fluid level and health.
- Get a transmission dipstick. It should have the “low,” “full,” and “fill” marks.
- Open the transmission hood and dip the stick inside.
- Take the stick out and place it on top of a white cloth.
- Compare the fluid color. If it’s reddish, the fluid health is perfect. However, the transmission fluid is contaminated if you see a dark color (brown or black).
- Next, check the fluid mark. If it hits low, you need to refill the tank.
Note: Make sure the car is parked on level ground when you are testing the fluid level.
#3- Humming /Buzzing/Grinding Noise
Noise can’t be the sole clue to identifying a transmission issue. However, once it’s backed up with delayed engagement, bad smell, and slipping, it helps to establish your doubt.
For example, I usually look for these strange noises while accelerating the car. If the car doesn’t respond to my gear shifting properly and also produces a buzzing noise the entire time, the Allison transmission has gone bad. It can happen to both manual and automatic ones. The only difference is the noise level.
You usually hear the humming or buzzing sound. Automatic transmissions also have more parts in them. On the contrary, manual transmissions have lesser parts. Still, you will hear the grinding or clunking sound resulting from rigorous friction and a low level of fluid.
Try to fix the fluid level first. However, the problem is most newer automatic transmissions (like Allison 3000) don’t come with a dipstick. So, the manual method won’t work here.
Rather, the vehicles have a keypad along with a display to showcase the level digitally. Follow the instructions below to check the fluid level on an automatic Allison Transmission.
- Press the “mode” button.
- Next, push the “up’ and “down” arrows at the same time.
- The fluid level would pop up on the screen.
- If it is “low” instead of “ok,” you have to refill the transmission.
If the noise doesn’t go away, the valve body of the transmission must have malfunctioned, causing the fluid to burn or get contaminated inside the tank.
#4- Odd Smell
For me, the easiest way to detect Allison 3000 transmission problems is through smell. Fresh transmission fluid doesn’t smell bad. So, if you notice an odd smell that is different from your engine oil, it must be from the transmission.
Here’s what happens. Either the Allison transmission has multiple leakages or worn bell housing. Whatever the reason, the transmission requires a quick inspection ASAP.
Don’t have professional tools to check for leakages? No worries. Apply the same dipstick or digital method I described earlier.
If the transmission level goes down sooner than its expected lifetime, you have your answer. If the leakage is bad, you might even see a puddle of transmission fluid underneath the vehicle.
#5- Vibrating Car
This one is a bit tricky among all the signs I have mentioned until now. There can be a lot of reasons why your car is shaking or trembling while you drive. The most common ones are damaged wheels, faulty suspension, and defective spark plugs.
Moreover, if the Allison transmission lacks enough lubrication or fluid, the same problem arises. That’s why it’s tough to blame the transmission at first glance.
However, if the vibrating car showcases any other signs from the above list, the chances only increase for it to be a transmission failure.
If you see a leakage in the transmission, that might be causing the fluid level to get low so fast. Hence, the lack of lubrication is causing overheating within the metal parts of the transmission.
conclusion
To recap, here are the 5 Common Signs Of Allison Transmission Going Out:
- Delayed response from your car
- Hearing unusual sounds while starting or accelerating
- A strange odor
- Check Engine Light Turned On
- Difficulty To Shift Gears
Most transmission errors originate from not maintaining the fluid level. So, before going to a mechanic, try to refill the tank with suitable lubricant (but not too much).
Usually, the check engine light activates when you cross the 60,000 miles limit without a single refill.
Video References
Scotty Kilmer
Mechanic Base
1A Auto
R A Diesel Tech
Certification: BSc in Mechanical Engineering
Education: Mechanical engineer
Lives In: 539 W Commerce St, Dallas, TX 75208, USA
Rasel is an auto mechanic student and writer with over half a decade of experience in the automotive field. He has worked with top automotive brands such as Lexus, Quantum, and also owns two automotive blogs autocarneed.com and taxiwiz.com.
