P0700 Code: What It Means and How to Fix It

Every year, cars require more and more computers to meet safety, fuel, and efficiency requirements. The good news is that our cars are more environmentally friendly than ever. They also perform better. Any car from the 1950s drives like a slow hog compared to a modern economy car. However, in this increasingly computerized automotive landscape, issues can arise, and one common problem that drivers may encounter is the dreaded check engine light, often accompanied by mysterious symptoms like rough or erratic shifting, the car running only in two gears, or an unexplained drop in fuel economy.

These symptoms indicate underlying transmission issues, and the solution lies in diagnosing and addressing transmission codes such as the notorious P0700.

But when those computer systems fail, they can be difficult to diagnose. In many cases, drivers find out they have a problem when a code scanner displays a trouble code.

Tools Needed For Diagnosis and Repair

Before we talk about repairs, make sure you have everything you need to fix the P0700 code. This includes:

• A flashlight or shop light so you can see what you’re doing
• A Philips screwdriver
• A universal socket set
• Electrical contact cleaner
• A multimeter
• An OBD2 code scanner or scan tool

What is a P0700 Code?

The P0700 code indicates that your vehicle’s Transmission Control Module (TCM) is malfunctioning. This computer monitors your transmission and works with the Powertrain Control Module (PCM) and Engine Control Module (ECM) to shift gears when necessary. It’s an integral part of any modern automatic transmission.

What Does Code P0700 Mean For My Car?

If your TCM isn’t working properly, you can experience a drop in gas mileage and rough, erratic shifting. These are concerns for any driver, but the biggest risk isn’t your wallet or comfort but your safety.

In some cases, a faulty Transmission Control Module can suddenly stop the car from shifting, affecting your vehicle’s speed. If your car gets stuck in fifth gear on the highway, your life may be in danger due to the reduced speed and lack of control. This is why it’s essential to diagnose and repair your TCM immediately.

Common Causes of the P0700 Code

There are three main causes of a TCM failure, which result in a P0700 fault code.

• Low or dirty transmission fluid. Your transmission needs clean, full fluid to run properly. Low or dirty fluid can cause your transmission to overheat and result in excess friction between moving parts.
• Faulty wiring. A short circuit or a corroded or broken wire can prevent your TCM from communicating with other car computers, leading to errors.
• A dirty or failed TCM. Usually, this requires replacing the TCM itself.

Common Symptoms Associated With a TCM Failure

Besides a P0700 code, you may experience other problems that alert you to a possible TCM failure. These include:

• Your check engine light is on
• Rough or erratic shifting
• The car only runs in two gears
• Your fuel economy drops for no apparent reason

If you’re experiencing any of these issues, you should have your codes read as soon as possible.

What Does Diagnosing the P0700 Code Entail?

To diagnose any automotive problem, it’s usually best to look for problems based on how cheap and easy they are to fix. The first is dirty or low transmission fluid. This can affect your transmission’s temperature and performance, leading to anomalies in the TCM and potentially triggering a generic code.

To fix this, check your transmission fluid to ensure it’s full and clean. Clean transmission fluid should be bright red. If your fluid is dirty, flush your transmission and fill it with fresh fluid. If your fluid is low but still red, top it off. Keep an eye on the level; you may have a small leak that caused your fluid level to drop.

If your transmission fluid is normal, the next thing you want to check is the TCM wiring. Using a multimeter, test all connections between the TCM, ECM, and PCM. Also, check the ground wire to make sure it’s not shorted out. If you find any issues, replace the defective wiring. Proper wiring is crucial, as any faults can lead to TCM errors and impact your vehicle’s overall fuel efficiency.

If you’re still experiencing problems, you can attempt a repair on the TCM itself. This process is advanced and is only recommended for people experienced with automotive repair. To learn more, read our detailed TCM repair guide. If you’ve attempted a repair and your TCM still returns an error code, you need to replace your TCM.

Common Mistakes When Diagnosing the Issue

The most common mistake when diagnosing the symptoms of a P0700 code is misidentifying the problem as a mechanical issue with the transmission itself. As you probably know, transmission repairs are expensive, far more than replacing a single computer. So not only will this misdiagnosis fail to fix the problem, but you’ll also spend a lot of money having unnecessary work done.

If you suspect that your TCM is causing your vehicle’s problems, have your codes read and look for P0700 or other TCM-related codes. If it’s a TCM problem, you can fix it quickly and easily. And if it’s not, you’ll have the peace of mind of knowing that your problem was mechanical.

Another common mistake is failing to check the wiring harness thoroughly. This can result in replacing a perfectly good TCM while leaving the underlying issue unaddressed.

Addressing Silverado and Trans Code Issues

Now, let’s shift our focus to another common issue that can trouble vehicle owners— the Silverado and trans codes. Professional mechanics play a crucial role in diagnosing and resolving these problems effectively. When your Silverado starts displaying mysterious codes related to its transmission, it can cause concern.

These trans codes, a type of diagnostic trouble code, often indicate underlying transmission faults, and ignoring them can lead to significant issues down the road. An experienced auto mechanic is your best ally in deciphering these codes and addressing any transmission fault promptly.

One frequently overlooked aspect that can contribute to various automotive problems, including trans codes, is bad batteries. Faulty batteries can cause electrical issues in your vehicle, leading to erratic behavior and even triggering check engine lights. Signs of damage from a bad battery may include corrosion around the terminals, swelling or leaking from the battery case, and difficulty starting the engine. A professional mechanic can perform a thorough battery inspection and replacement, ensuring your vehicle’s electrical system is in top shape.

Possible Solutions For Fixing the P0700 Code

• Topping off or replacing the transmission fluid
• Repairing or replacing the wiring harness
• Replacing the TCM

How Can SOLO Help?

If you need to replace your TCM or any other car computer part, contact us or call 888-886-9926. Our experienced technicians, with decades of expertise in repairing automotive computers, are here to guide you every step of the way. Ready to get your replacement parts? Trust SOLO to provide reliable car computer solutions to keep your vehicle running at its best! Order your car computer or send it in for repair today!