by Sam Dillinger (comments: 0)
P0700 Transmission Control System
Today we’re going to take a quick look at P0700. I didn’t finish defining the name of the Pcode because it reads differently depending on what scanner you use and what manufacture makes your vehicle. They all mean the same thing though. This Pcode is the most frequently mis-interpreted of all of them. A lot of people see this Pcode and immediately think that the TCM, Transmission Control Module, has failed and needs to be replaced. That isn’t the case however. This Pcode is purely informational. It is literally telling you that there are Pcodes related to the transmission present. That’s all it means. It doesn't condemn any component or sub-system, just that there is a problem with the transmission and further investigation is needed.
Here’s how it works. The PCM, Powertrain Control Module, is the only module on the vehicle that is capable of turning on the check engine light. However, the TCM may need to turn on the check engine light to alert you to a failure. To do this, the TCM will record any Pcodes it has detected, and then it will send a signal to the PCM. The PCM will then record the P0700 Pcode, because there has to be a Pcode present for the engine light to come on, and that will turn on the check engine light, alerting you to take a look. This Pcode does not mean to replace the TCM! I’ve had quite a few customers come to me over the years and tell me they had their vehicle at a shop and this Pcode came up. The shop sold them a TCM, and on the drive home the check engine light came back, or even worse, before they even left the shop!
It’s important to note that some scanners don’t have the ability to speak to a TCM, so P0700 will be the only Pcode reported by these scanners. If you find this Pcode, but don’t see the TCM as an option to read, then you’ll need to get access to a more advanced scanner. Once you do, you’ll find there’s at least one Pcode recorded in the TCM, and then you can begin a correct diagnosis. It’s also important to note that this Pcode may not have any noticeable symptoms that come with it. The transmission may not go into “limp’, or “safe” mode. In fact it may still be operating just fine, and only the Pcode will give any immediate indication that something is wrong. That doesn’t mean that it’s ok to continue driving. Quite the opposite actually. If you have this Pcode, and no observable symptoms, you’ve got a chance to fix the condition before any worse damage occurs.
As I noted at the beginning, this is purely an informational Pcode, so this is all the explanation required. As always, for my members, if you've got further questions, need some diagnostic assistance, or want some clarification on something I've said, stop by and see me at www.mycheckenginelight.net
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Meet Sam Dillinger
My name is Sam Dillinger. I've been a professional, dealership technician for 18 and a half years. My first introduction to mechanical repair was when my own vehicle broke down in the fall of 1995. I was 18 and couldn't afford to pay to have it fixed. So I borrowed tools and asked a ton of questions and, eventually, was able to replace the clutch on my truck by myself. During the course of that project, I found that I really enjoyed having a wrench in my hand and figuring out the puzzle of disassembly and reassembly of a motor vehicle.