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Error Code P0817 is defined as Starter Disabled Circuit. Error Code P0817 is a generic trouble code, meaning it applies to all vehicles with the OBD-II system, especially those made from 1996 up to present. This includes vehicles from, but not limited to, Audi, BMW, Mazda, Subaru, and Volkswagen. Specifications on the definition, troubleshooting, and repairs, of course, vary between make, model, and powertrain configuration.
If the vehicle stores the Error Code P0817, this means the PCM (powertrain control module) has determined a malfunction in the starter disable switch circuit. This code applies to both automatic and manual transmissions.
The starter which disables the switch is usually a single circuit, open/closed switch, which interrupts the voltage between the ignition switch, and the starter solenoid. If the clutch is not depressed, the transmission (manual) is not in neutral, or the transmission (automatic) is not in the park. Vehicle applications with an automatic transmission may have the starter disable switch integrated into the neutral safety switch or shift selector switch. The transmission control module (TCM) or the PCM monitor starter disable circuit voltage with the ignition in the ON position. The TCM may be a stand-alone module or part of the PCM.
If the PCM sees that the starter disable switch circuit voltage is outside its set parameters, then this code will be set and simultaneously activate the Check Engine light. In some cases, multiple ignition cycles (with a failure) may be needed to activate the Check Engine light.
- No start condition for the engine
- The engine starts with the transmission in gear
In other cases, the vehicle may not show symptoms at all.
- Defective starter disable switch
- Shorted or open wiring or connector in starter disable switch circuit
- Defective or programming error in the PCM
How to Check
You will also need a diagnostic scanner, DVOM (digital volt/ohmmeter), and a source of vehicle diagnostic information.
Use the vehicle’s information to find the TSB (technical service bulletin) that matches the specifics of the vehicle (make, model, engine size, symptoms, and codes stored). This could help for a more thorough diagnosis.
Use the scanner (connected to the vehicle diagnostic connector) to retrieve all stored codes and pertinent freeze frame data. It is a good idea to write this information down before clearing the codes then test-drive the vehicle until the PCM either enters readiness mode, or the code is reset.
If the PCM enters readiness mode at this time, the code is intermittent and may be much more challenging to diagnose. If this is the case, the conditions which contributed to the code being stored may need to worsen before an accurate diagnosis can be made.
If the code is immediately reset, the next step of your diagnosis will require that you search your vehicle information source for diagnostic flow-charts, connector pin-out charts, connector face views, and component testing procedures/specifications.
Test the voltage, ground, and signal output at the right downshift switch using the DVOM. Typically, the downshift switch circuits consist of either the battery voltage (when activated) or the ground (if deactivated).
If all the system circuits are working properly, then test the downshift switch circuits to the PCM or the transmission using the DVOM. Make sure you disconnect all controllers before using the DVOM for testing.
Test the downshift switches using your source of vehicle diagnostic information and the DVOM. Switches that don’t test within the system’s specifications must be replaced.
Note that starter disabled switch circuit error codes are likely related to switch failure.
Also, manual transmission vehicles usually use multiple starter disable switches (one for the clutch and another one for neutral).
How to Fix
- Repair or replacement of primary battery cable
- Repair or replacement of the battery
- Repair or replacement of starter disable relay
This error code may come with a no-start condition, which means it is either an electrical or mechanical problem. Nevertheless, it should be addressed as soon as possible.