P0790 – Normal/Performance Switch Circuit

System: Powertrain | Standard: ISO/SAE Controlled | Fault type: Circuit

Definition source: SAE J2012/J2012DA (industry standard)

DTC P0790 indicates a fault in the Normal/Performance Switch Circuit. In vehicles equipped with a selectable driving or shift strategy, this switch (or its equivalent input) provides the control module with a driver-requested mode selection. When the module detects that the circuit signal is not behaving as expected for normal operation, it stores P0790 and may default to a substitute strategy to protect drivability. The exact monitor logic, wiring layout, and how mode selection affects operation varies by vehicle, so confirm the circuit design, connector views, and test specifications in the correct service information before probing or replacing parts.

What Does P0790 Mean?

P0790 means the powertrain control system has detected an electrical fault condition in the Normal/Performance Switch Circuit. The official definition is strictly circuit-focused: the issue is with the switch input circuit used to indicate a Normal versus Performance selection, not a confirmed mechanical problem. Under SAE J2012 DTC structure conventions, this code identifies a specific monitored circuit whose signal must remain within expected behavior and plausibility rules for the selected mode. The module sets P0790 when the input from the Normal/Performance switch circuit is missing, inconsistent, stuck, or otherwise not credible compared with what the module expects during operation (criteria vary by vehicle).

Quick Reference

• Subsystem: Normal/Performance mode request switch circuit (driver input to the powertrain control system).
• Common triggers: Switch input stuck in one state, implausible state changes, intermittent contact, or a circuit signal that does not match expected behavior.
• Likely root-cause buckets: Wiring/connector issues, switch assembly fault, power/ground/reference issues (as applicable), control module input fault or calibration/logic dependency (varies by vehicle).
• Severity: Usually moderate; may alter shift strategy/response and disable mode selection, but can contribute to drivability complaints.
• First checks: Verify mode switch operation in live data, inspect connectors and harness routing near the switch and module, check for moisture/corrosion and poor pin fit.
• Common mistakes: Replacing the switch without verifying the circuit (power/ground/reference and continuity) or ignoring intermittent harness faults that only appear with vibration.

Theory of Operation

The Normal/Performance switch circuit is a discrete input (or a networked input routed through a body/control module, depending on vehicle design) that tells the powertrain controller which operating mode the driver requested. The switch may change the state of a signal line using a pull-up/pull-down strategy, a resistor ladder, or a referenced input that the module interprets as “Normal” or “Performance.” The controller continuously monitors this input while the vehicle is operating and, in some designs, at key-on as part of an initialization check.

The module considers the circuit “OK” when the input transitions cleanly, remains stable when the switch is not being operated, and stays plausible compared with other information (for example, a commanded mode change request). P0790 sets when the input is missing, unstable, stuck, or otherwise not performing as expected for the circuit design. The exact enable conditions and decision logic vary by vehicle, so always verify with service information.

Symptoms

• Mode inoperative: Normal/Performance selection does not change vehicle behavior or the selection will not register.
• Indicator mismatch: Mode indicator (if equipped) does not match the requested switch position or flickers.
• Driveability change: Noticeable change in shift feel, throttle response, or overall powertrain behavior due to a default strategy.
• Intermittent complaint: Symptoms appear only over bumps, during turns, or when the steering column/console area is moved (varies by switch location).
• Warning lamp: Malfunction indicator lamp and/or a powertrain warning message may illuminate.
• Failsafe behavior: System may revert to a single mode (often defaulting to a conservative strategy) until the fault is cleared and the input is verified.

Common Causes

• Damaged wiring in the normal/performance switch signal circuit (chafed insulation, broken conductors, pinch points)
• Loose, corroded, backed-out, or moisture-contaminated terminals at the normal/performance switch connector or control module connector
• High resistance in the circuit (poor splice, partial conductor break, fretting at terminals) causing an implausible or unstable switch signal
• Intermittent open in the switch circuit due to harness movement, vibration, or poor pin fit
• Normal/performance switch internal fault (stuck contacts, inconsistent switching, internal wear)
• Shared reference/return issues affecting the switch input (common ground splice or shared return circuit problems, varies by vehicle)
• Incorrect installation or misadjustment of the switch assembly (where design uses alignment, mounting, or mechanical indexing)
• Control module input circuit concern (less common), such as an internal input fault or software/logic issue after all external checks pass

Diagnosis Steps

Tools typically needed include a scan tool capable of reading live data and recording logs, a digital multimeter for circuit checks and voltage-drop testing, and basic backprobing tools with terminal-safe probes. A wiring diagram and connector pinout from service information is essential because circuit routing and switch logic vary by vehicle. If available, use a breakout lead or test harness to reduce terminal damage risk.

1. Confirm the code and context. Scan for DTCs, document P0790 along with any companion powertrain or input-signal codes, and save freeze-frame data. Clear codes and see if P0790 resets immediately or only after operating the switch or driving.
2. Verify the customer complaint and switch operation. Operate the normal/performance mode switch as intended (varies by vehicle). Note whether the indicated mode changes consistently (cluster indicator or scan tool parameter) and whether the change is delayed, intermittent, or not detected.
3. Check scan tool live data for plausibility. Find the PID(s) related to the normal/performance switch input and mode status. Toggle the switch repeatedly and watch for stable, repeatable transitions. If the status flickers, lags, or changes without input, treat it as a range/performance behavior and proceed with wiring integrity checks.
4. Perform a focused visual inspection. Inspect the switch area, harness routing, and connectors for rubbed-through insulation, signs of liquid intrusion, prior repairs, bent pins, and connector lock damage. Pay attention to harness segments that flex during normal operation (console/column movement, drivetrain movement, or underhood routing, varies by vehicle).
5. Wiggle test while monitoring live data. With the scan tool showing the switch PID, gently manipulate the harness and connectors near the switch and near the control module. Look for PID dropouts, unexpected toggles, or rapid oscillation. If the signal reacts to movement, prioritize connector terminal fit and conductor integrity.
6. Check connector terminal condition and pin fit. Disconnect the switch connector and the module-side connector (as applicable per service info). Inspect for corrosion, spread terminals, push-outs, and damaged seals. Verify terminal tension using the appropriate method (terminal drag or pin-fit check per service procedures). Repair any terminal issues before further electrical testing.
7. Test for opens/high resistance in the signal path. Using the wiring diagram, measure circuit continuity end-to-end (switch to module pin) and check for excessive resistance relative to service expectations (do not assume a universal value). Flex the harness during the test to catch intermittent opens.
8. Check for shorts between circuits. With connectors unplugged, test for unintended continuity between the switch signal circuit and adjacent circuits in the harness (including other switch inputs, reference, and return circuits). Any cross-short can create implausible switch states and trigger a performance-type fault.
9. Perform voltage-drop testing under operating conditions. Reconnect the circuit and backprobe safely (or use a breakout). Operate the switch while measuring voltage drop across key points (connector-to-connector, across suspected splices, and across ground/return paths if used). Excessive drop indicates high resistance that can distort the input and cause an out-of-range/performance condition.
10. Evaluate the switch itself. If wiring and connectors pass, test the switch function per service information. Confirm it produces consistent state changes without bouncing or sticking when actuated. If available, compare the switch input at the module pin to the switch-side behavior to isolate the fault to the component versus the harness.
11. Consider module-side causes last. If the input at the module pin is stable and correct but the scan tool PID or mode logic remains implausible and P0790 returns, follow service information for module input diagnostics, software checks, and any relearn/setup steps that may apply after repairs.

Professional tip: Treat P0790 as a plausibility/range-performance problem until proven otherwise. That means your best evidence is repeatable live-data behavior: log the switch PID, mode status, and any related inputs during a short drive and during harness manipulation. If the PID is stable at the module pin but unstable in the data stream, you’ve narrowed the issue to processing/logic; if it changes with a wiggle test, focus on terminals, splices, and high-resistance faults.

Possible Fixes & Repair Costs

Repair costs for P0790 vary widely because the normal/performance switch circuit design, access, and required confirmation tests differ by vehicle. Final cost depends on whether the issue is wiring, the switch itself, a connector/pin-fit concern, or a module-side input problem.

• Repair or replace damaged wiring in the normal/performance switch signal, power, or ground circuits (as applicable)
• Clean, reseat, and secure connectors; correct poor terminal tension, bent pins, or corrosion found during inspection
• Replace the normal/performance switch (or the selector assembly that contains it) if it fails functional testing
• Restore proper power supply and ground integrity to the circuit using confirmed voltage-drop test results (repair high resistance points)
• Repair harness routing issues causing chafing, pinched wires, or intermittent opens/shorts during movement
• Update or reconfigure control module software only if service information calls for it and all circuit tests pass
• Replace the control module only after verifying the input circuit is correct and the module is not interpreting a valid signal improperly

Can I Still Drive With P0790?

You can often drive with P0790, but do so cautiously because the control module may default to a substitute strategy that limits mode selection or alters shift/response behavior. If you notice harsh or unexpected shifting, reduced power, warning lamps related to powertrain control, or any safety-related symptoms, avoid driving and diagnose the circuit promptly.

What Happens If You Ignore P0790?

Ignoring P0790 can lead to persistent mode-selection problems, inconsistent performance behavior, and potential drivability complaints that may worsen if the underlying circuit fault becomes intermittent-to-hard failure. Continued operation with an unresolved circuit issue can also complicate future diagnostics by adding additional fault codes.

Last updated: March 9, 2026

Vehicles Commonly Affected by P0790

• Vehicles equipped with a driver-selectable normal/performance mode switch input to the powertrain controller
• Vehicles where the mode switch is integrated into a console shifter/selector assembly
• Vehicles that route the switch signal through a body or gateway module before reaching the powertrain controller
• Vehicles using multiplexed switch arrays or resistor-ladder style inputs for mode selection
• Vehicles frequently exposed to moisture, dust, or spills near interior switch assemblies and connectors
• High-mileage vehicles with harness flex points near the console, dash, or transmission tunnel
• Vehicles with recent interior work, accessory installations, or wiring repairs near the mode switch circuit
• Vehicles operating in environments with high vibration where intermittent connector contact is more likely

Confirm the repair by clearing the code, performing a road test under conditions that normally use the normal/performance switch, and rechecking for pending or stored faults while verifying the mode request signal remains stable.