Allocating two resistive pedal channels in the vehicle readout chain

System boundary

Pedal motion through shared mechanism, two wipers and tracks, electrical supplies, harness routes, controller inputs and diagnostic action

Draw two channels and their shared dependencies

Start with pedal travel, mechanical stops, return springs, carrier and both wipers. Draw channel A and channel B from contact position through track terminals, supplies, returns, connector pins, harness conductors and controller inputs. Mark every point where the paths share mechanics, power, ground, enclosure or software. Two output wires do not imply two independent sensing chains.

State the intended channel relationship: same slope, opposite slope, offset ratio, different ranges or another controlled correlation. Define valid operating window and diagnostic window separately. The resistor card owns drawing-defined track and terminal behaviour; pedal authority, controller comparison, torque request and safe reaction remain outside the component boundary.

Test shared pedal and wiper motion

Measure pedal reference, carrier position and both wiper coordinates throughout application and release. A cracked carrier, jammed pedal or common shaft displacement can move both contacts consistently to the wrong physical state. Cross-channel agreement would then be plausible but false. Independent mechanical reference is necessary to reveal that failure.

Record preload, contact force, alignment, stop engagement, backlash and overtravel. Check whether one wiper can lift without changing the other and whether contamination can bridge or obstruct both tracks. A redundant electrical calculation cannot compensate for an undefined shared mechanical path.

Define the cross-channel transfer equation

Fit or specify the allowed relation y_B=a y_A+b over the usable travel, using raw controller-node values or another declared electrical boundary. The diagnostic residual is e_corr=y_B-(a y_A+b). Evaluate residual against pedal position, direction, supply state and temperature; a single maximum cannot show a localized track event.

For an example, if a=0.5, b=0.2 V, y_A=4.0 V and y_B=2.3 V, the residual is 0.1 V. This checks arithmetic only and defines no vehicle threshold. The integrator supplies normal correlation bands, diagnostic timing and fault reaction.

Allocate supplies, returns and harness paths

Document whether channels use independent or shared supply and ground nodes, how connector pins are spaced, where harness conductors run, and whether controller ADCs share a reference or multiplexer. Analyze opens, shorts to supply, shorts to ground, cross-shorts and resistive leakage. Independence claims require physical and diagnostic evidence at each shared point.

Acquire both card-terminal and controller-input values. A disturbance at the controller but not at the card locates wiring or input circuitry. Matching shifts on both channels may indicate shared supply or mechanical motion. Different filter delays can create a transient residual even when contacts are correct, so raw time alignment belongs in the interface definition.

Diagnose single-channel and common-cause patterns

A single abrupt deviation with stable pedal reference and companion channel directs attention to that contact, track or electrical path. Both channels moving together away from independent pedal position challenges shared mechanics or reference. A complementary change of two signals may indicate a cross-short. An unchanged plausible pair with a jammed pedal demands a separate mechanical diagnostic.

Retain raw signals, supply nodes, pedal reference and controller decisions around the event. Do not tune correlation limits to hide an unexplained failure. The controller owner decides debounce, plausibility timing, latching and recovery.

Evaluate considered faults without claiming safety

Create a fault list tied to the actual architecture. For arithmetic tracking, diagnostic coverage may be expressed as C_diag=N_detected/N_considered. Detecting eight of ten considered cases gives 80 percent within that list; it is not a safety metric unless severity, exposure, independence and diagnostic effectiveness are established by the integrator.

Document which faults are latent, which can combine, and which tests run at startup, continuously or during service. A second track may improve observability but can also share a wiper carrier, connector, supply or software defect. Unknown hazard analysis remains open.

Validate synchronization, faults and response

Use representative pedal mechanics, card, wipers, connector, harness, supplies and controller inputs. Exercise full travel, reversals, dwell, vibration and temperature states. Inject authorized electrical faults at defined interfaces and challenge mechanical common causes separately. Establish valid-run and reset rules before reviewing results.

Synchronize independent pedal position, both wiper coordinates, terminal signals, controller samples and diagnostic state. Confirm on assemblies not used to set correlation parameters. Acceptance and safe state are integrator requirements. No functional-safety, automotive or regulatory approval is claimed.

Pedal-channel evidence becomes more useful when the two outputs are plotted against a common mechanical coordinate and against each other. Use slow forward travel, slow return, controlled dwell points and representative actuation rates. Record independent supply and return voltages at the connector so a shared harness drop is not mistaken for simultaneous track movement. Introduce only customer-approved electrical faults, one at a time, and confirm the controller reaches its intended safe response without depending on a plausible but incorrect second channel. Mechanical common-cause behavior requires separate attention: a single carrier, shaft or stop can move both signals together. Acceptance therefore belongs to the complete pedal and controller architecture, not to an isolated resistance reading from either printed path.

Control revisions that affect independence

Link pedal and carrier revisions to both wipers, tracks, connector, harness, supply architecture, ADC configuration and diagnostic software. Changing pinout, ground routing, filter, contact layout or mechanical carrier can alter common-cause exposure even when nominal curves are unchanged.

Reevaluate the fault list and cross-channel equation after consequential changes. State which evidence remains valid. Similar resistance ranges do not establish the same diagnostic behaviour or independence.

RFQ inputs for a dual-track pedal card

Provide pedal travel, stops, carrier and wiper geometry, contact loads, two required curves, cross-channel relation, terminal assignment, supplies, returns, connector and harness. Include controller impedance, ADC references, sampling, filtering, diagnostic intervals, environment, duty, quantity and failure consequence.

Identify integrator acceptance, fault list and safe-response ownership. If independence assumptions, diagnostic timing or controller boundaries are missing, list them for application review rather than inferring compliance.