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Chevrolet Silverado 2014-Present: How to Diagnose a Bad Transmission

The automatic transmission in your Chevy Silverado is a rugged, electronically-controlled 6-speed that is programmed to just work. If you feel something that does not seem right, check it out sooner rather than later.

By Mark Garrett - June 1, 2015

This article applies to the Chevrolet Silverado 1500 (2014-present).

When you get in your truck and put it in drive, you expect it to go just like it always has. So what if something feels unusual one day? Not shifting or hard, jerky shifts may mean something is wrong. It is best to check the issue out as soon as possible. Next to your engine, the transmission is the most expensive component on your vehicle. The PCM (Powertrain Control Module) is the computer that ultimately controls it. It also stores OBD (On Board Diagnostic) codes to help reveal issues. The PCM is the brain and the actual transmission is the brawn.

It is easy to check the basics before spending a lot of money. Here there are some of them that you can check out yourself.

Materials Needed

  • Rags
  • OBD reader
  • Dexron VI trans fluid
  • Transmission filter kit

Step 1 – Check transmission fluid

This is rather basic, but the transmission fluid level must be correct for your transmission to work at its best. Since the fluid provides lubrication, cooling, and pressure in the transmission, it needs to be fresh and it needs to be the correct level.

With the engine running, check the transmission fluid level. It must read in the Normal Operating range.

  • If it is not in the proper range, add fluid slowly until it is. Never overfill an automatic transmission.
  • While you have the dipstick out, look at and smell the fluid. It should smell clean with no burnt odor and look pinkish. It should never be brown as that tells you the fluid has been burnt and there is a problem.
Figure 1. ATF test.

Pro Tip

Your Silverado probably has a transmission fluid cooler on it from the factory. If it doesn't, then you may want to consider installing one. A transmission that runs cool will last longer.

If your fluid smells and looks fresh, the good news is that there is probably nothing horribly wrong with your transmission. If the fluid seems to be a bit tired-looking, you may want to go to the next step.

Step 2 – Change the transmission fluid and filter

The transmission filter keeps keeps the fluid clean so the transmission has clean fluid in it. Changing the fluid and filter is a maintenance item.

Fortunately, GM made it fairly easy to change the fluid and filter in your Silverado 1500. If you drop your pan and there is debris in the bottom, it is not optimal but may not be the end either. Figure 2 shows what you would be happy to see when you drop your pan.

Figure 2. Normal-looking pan.

Step 3 – Check the OBD codes

The OBD trouble codes are stored in the PCM. Some are easy to get to but some remain deep in the PCM memory. Depending on what may be wrong with your truck it may be necessary to have a dealer or large shop read your codes rather than the local auto supply store. In the past the TPS (Throttle Position Sensor) has caused shifting problems which is an easy fix. Torque convertors also had issues, but this is a tough repair. The PCM is smart enough to tell if there is something going awry, but you may not be able to find the issue or resolution yourself.

Figure 3. OBD port.

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