Northwest Metro Denver

3686 W. 72nd Ave
Westminster, CO 80030
8AM – 5:30PM Mon-Fri

(303) 421-4140

(303) 421-4140

Southwest Metro Denver

SE Corner Mississippi & Pierce
1194 S. Pierce
Lakewood CO 80232
8AM – 5:30PM Mon-Fri

(303) 922-4102

(303) 922-4102

Lakewood 303-922-4102

Westminster 303-422-4140

DIY Transmission Repair: Can I Handle Transmission Troubleshooting Myself?

Can I Handle Transmission Troubleshooting Myself?

If you’ve been driving and recently heard an unfamiliar clunk from under your car, you might be wondering, “Can I handle transmission troubleshooting myself?” That’s a good question, and there’s no simple answer. The best answer—as frustrating as it might be—is, it depends. No, don’t crawl back under the covers. If there is a problem, you shouldn’t wait to address it because it will only get worse.

What does it depend upon? First, it depends on your willingness to get a little dirty and go wherever the investigation takes you, from under the hood to under the car to researching on a computer. Second, it depends on the way your vehicle was made. If you have a transmission that has no dipstick access to check the fluid—and you may be surprised to find out yours is one of them–you aren’t going to be able to determine much without visiting your local transmission repair shop.

Common Transmission Problems

There are a handful of problems that are common to each transmission model. Years ago, 5-8 transmission types accounted for the vast majority of transmissions on the road. Now there are over 300 transmission models with its own unique set of known problems. The causes and solutions to those problems range from relatively straightforward to extremely complex. Here’s a breakdown:

Fluid Leak: Most cars use red transmission fluid, and that can make it easier to spot unless it has burned and changed to brown. If that is the case, it will smell like burnt toast. Some causes for a fluid leak include a leaking pan, defective pan gasket, faulty seals, loose pan bolts, leaking fluid lines, pump failure or a faulty torque converter.

Overheating Transmission: Transmission fluid is an essential component in any transmission. If that fluid level is low, or if it becomes burnt or ineffective, your transmission will overheat. Even if the fluid is not burnt and simply old, the friction modifiers within the fluid get used over time and fail to manage temperature as initially designed. Other causes include clogged cooler lines, hauling, towing, stop-and-go traffic, radiator failure, hot climates, or a defective solenoid.

Clicking or Whining Noises: This can be caused by low fluid levels or a faulty torque converter. Another cause may be worn or damaged planetary gears. Some whines are problematic as it can be a machining problem with the actual transmission case. Having to replace the case is challenging and, in these situations, it might be advisable to consider a remanufactured unit.

Slipping gears or vehicle will not move forward or in reverse: No one wants to have this happen because it often signals an expensive repair. There are a few different possibilities when diagnosing these symptoms, including low fluid levels, defective solenoid, worn gears, broken bands, damaged drum, or burnt clutch plates.

Delayed or Erratic Shifting: This can also be caused by low fluid levels. Other causes could be from using the wrong fluid, burnt fluid, broken vacuum lines, or, again, a defective solenoid. Transmissions were traditionally mechanically or hydraulically controlled. Today, most transmissions have a unique TCM (transmission control module) that works with the PCM (powertrain control module) to shift gears based on countless inputs from sensors across the vehicle. Any one of these sensors, internal or external to the transmission, can cause a problem. Moreover, problems in the electrical system of the vehicle (e.g., battery, alternator, wiring harness) can lead to misdiagnosing a good transmission as bad. This is a costly mistake!

Engine Codes

If your vehicle is throwing an engine code, you can take your car to an automotive supply retailer, and they will use a tool and check them for you. They will give you the codes if there are any, and what you do with them is up to you. 

Most people will be tempted to look them up on Google, but keep in mind, that isn’t a whole lot different than diagnosing an illness using WebMD. Transmission techs use specific libraries to look up codes and use them to determine the underlying cause of the problem. Commentary from professionals and access to trained technicians is more valuable than advice from an untrained car enthusiast. This can help guide a tech to recommend a small repair instead of replacing the whole transmission, something that is much more likely to happen using Google. Customer education in transmission repair is absolutely critical, as is an individual’s research on a drug a doctor might prescribe to take; however, there is a reason technicians spend a career focused on one component of a vehicle… because it’s extremely complicated!

Problems Often Misdiagnosed as Transmission

There are also some problems that are commonly misdiagnosed as transmission problems. They include worn engine mounts, engine misfire, faulty fuel delivery system, restricted air flow, or a faulty temperature, mass airflow or speed sensor.

Get a TrueTest Inspection

If this is a bit overwhelming for you, or you just don’t have time to tackle it yourself, give us a call at Advanced Transmission Center and come in for a TrueTest Inspection. We will be happy to run all the tests, show you the results, and give you all the options, should a repair be necessary.  Even if you just want a second option, give us a call.

Nothing is more important than an accurate diagnosis, and that is what you will get. Our TrueTest Inspection uses the best diagnostic equipment available in the industry, checks the transmission pan for metal, checks fluid levels and condition—even if there is no dipstick in the engine compartment—and includes both a road test and a multi-point lift test. 

Schedule a FREE Diagnosis today!

Westminster – Northwest Metro Denver: (303) 421-4140
Lakewood – Southwest Metro Denver: (303) 922-4102

Owner at Advanced Transmission Center | Website | + posts

Advanced Transmission Center is a Colorado-owned and operated auto repair shop with locations in Denver / Lakewood and Westminster. ATC specializes in driveline issues such as automatic transmission repair, four wheel drive repair, clutch replacement, differentials, manual transmissions and CVT. As Colorado's first AAA approved shop our goal is to provide accurate, timely service with exceptional customer satisfaction. All of our technicians are certified in the latest makes and models and we are one of the few transmission repair shops with a nationwide warranty.

This entry was posted in Transmission Tech. Bookmark the permalink.

Comments are closed.

Our Commitment to You

Free towing is just one of the ways we strive to save you money on a major in-house repair such as a transmission rebuild. With our thorough TrueTest™ Inspection process, you will fully understand what is wrong with your car and only pay for the repairs you need.
Every transmission repair should start with a thorough and accurate diagnosis of the problem. Our multi-step TrueTest inspection procedures have been designed over decades to identify whether a minor repair can fix your issue or if a major repair is required.
We can turn around a transmission repair in as little as 2 days with our fast services! Our in-house rebuild department, expert technicians and strong vendor relationships help us get vehicles fixed ASAP. It also helps to have two local repair shops with identical operating procedures and quality standards.
After a major repair, you can take a breath and know Advanced Transmission Center has your back! We offer various warranty options (1-year, 2-year, 3-year, local or nationwide) and make sure any warranty claim is hassle-free for our customers.

Makes We Serve


Meet The Team

Get to know the team at Advanced Transmission Center

Your Transmission Repair All Star Team Contact Us

A Name You Can Trust

  • ASE
  • Angies List
  • ATRA
  • Certified Transmission
  • BBB A+
  • Referalist
  • Yelp

© 2024 Copyright. Advanced Transmission Center. All rights reserved.