P0816 OBD Error Code: Problem & Solutions

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The Engine Control Module or the ECM of your vehicle may find a problem with the downshift switch circuit, when it notes such a malfunction it will set P0816 code. This downshift switch circuit includes the switch, its connectors and system wiring and also the mode actuator. It can be found located near the shifter in the passenger’s compartment of your vehicle, this can only be found in vehicles that have an automatic transmission that can be shifted manually also known as automated manual.

The ECM calculates the data using solenoids which actuate the fluid transfer between hydraulic circuits for each gear, this helps in initiating the downshifting and upshifting. When the voltage reading or resistance signal received by the ECM is not in the manufacturers prescribed ranges, the ECM will set P0816 code.

What causes this problem with the Downshift Switch Circuit?

• Damages or defects present in the transmission gear selection switch
• Open or shorted Gear selection switch harness is open or shorted
• Liquids leaking into the downshift switch and causing damages
• Transmission gear selection switch has damaged, corroded or poor electrical connections to it

1. Vehicle’s Upshift/Downshift Switch - Look for damages and repair or replace them accordingly and see if the P0816 code returns
2. Powertrain Control Module - If you have to replace your PCM, don’t worry, you can find one that’s perfect for your vehicle on Parts Avatar. Order from the comfort of your home and have it reach your doorstep within a matter of days. You can avail free shipping on order above $99.
3. Vehicle’s Shifter - Get rid of your P0816 code by repairing or replacing the issues with the shifter.
4. Check Engine Light - Be thorough and see if you can repair the issue with the light, if not replace it.
5. Engine Control Module - Replace your ECM is needed with Parts Avatar. We have a wide range of auto parts that you buy online from the comfort of your home. Take help from our online customer service 24/7 to get exactly what you’re looking for.
6. Diagnostic Tools - Only the best and accurate diagnostic tools will help you when trying to resolve the P0816 code. We stock a wide range of brands for you to select as per your requirement.

For us our customers are everything, and that’s why we will help you to diagnose P02BA code by mentioning some important symptoms below:

Common Symptoms

• Check Engine Light is illuminated
• No symptoms may be found other than the P0816 code being stored
• Disabled Manual shifter function
• Vehicle goes into “limp” mode
• Overdrive light may also flash

After you know the symptoms of your vehicle’s problem, it becomes easy to detect it and get started with solving it. So, next on our list is few common steps to correct this issue with your vehicle’s.

• Repairing or replacing the damaged or faulty circuits and connectors of the downshift switch
• Replacing the damaged downshift switch
• Replacing the damaged or defective downshift solenoid
• Repairing or replacing damages or defectiveness found in the circuits or connectors
• Repairing or replacing “normal/performance” switch as per need
• Damaged or defective ECM has to be repaired or replaced even though this is very rare
• Repairing and replacing all the damaged or burned downshift switch circuit wiring or connectors

Apart from this, you might need to replace other damaged parts too like Vehicle’s Upshift/Downshift Switch, Upshift Switch, Powertrain Control Module, Vehicle’s Shifter, Check Engine Light and more. You can easily find all these parts with us. Not only that you can get these parts shipped to your door free, if your cart value happens to exceed $99.

Here are some steps which you should follow in order to diagnose P0816 error code:

• Get hold of all the tools you will need, procure a diagnostic scanner, a digital volt/ohmmeter or DVOM, a reliable vehicle information source. Look through the information source and locate your specific vehicles technical service bulletins of TSB, as per the make, model, year, engine of your vehicle. It is important to match it correctly with the code as well as the symptoms exhibited, if you are able to find it in the TSB you can get plenty diagnostic help from there.
• Use the scanner and connect it to the vehicles diagnostic port and retrieve all the codes stored, and freeze frame the data. Make note of them in their order too, for reference in the future in case the error is intermittent. Now clear all the codes and take your vehicle on a test drive. Wait until the code is restored or the PCM enters readiness mode.
• If the PCM enters readiness mode it is because there is an intermittent condition. These are rather difficult to diagnose and, in more cases, require the problem to get worse before correct diagnosis can be drawn. If the code immediately rests, then you need to look through your vehicle information source for diagnostic flow-charts, connector pinout charts, connector face views and component testing procedures. These will also help you locate the correct components so that you don’t meddle with the ones not associated with this error.
• Now, using the DVOM test the voltage, ground as well as the signal output at the downshift switch. The downshift switch circuits in general will consist of either a battery voltage when active or a ground when deactivated. If you find that the system circuits are functioning just fine then use the DVOM to test the downshift switch circuits going to the PCM or transmission. Remember to disconnect all the controllers before using the DVOM for testing. Now refer your vehicle information source as well as the DVOM and test downshift switches as needed.
• All the switches that aren’t fitting into the specifications of the manufacturer will have to be repaired or replaced. The codes that are associated with downshift switch are present due to switch failure.
• Once all the repairs are done, clear the codes and check if it resets. If it does you can suspect an issue with the PCM.

Common mistakes when diagnosing the P0816

• Overlooking liquid leaks into the switch and wrongly concluding an issue with transmission wiring
• Diagnosing a problem with the PCM without thorough check of the transmission and its components

P0815 - Upshift Switch Circuit