P0322 - Ignition/Distributor Engine Speed Input Circuit No Signal

P0322 - Ignition/Distributor Engine Speed Input Circuit No Signal

Overview

• P0322 is an OBD-II powertrain code indicating the engine speed input circuit from the ignition/distributor (commonly the crankshaft position reference) is not producing a signal to the PCM/ECU.
• In the Open Source code definition, this is described as , i.e., no signal on the engine speed input circuit (Ignition/Distributor). This aligns with the general concept of a missing crank/engine speed reference. Source: Open Source code definitions.
• Background context: OBD-II powertrain codes cover engine/drive systems and the PCM's monitoring ofengine speed input signals. This guide draws on general OBD-II tech from Wikipedia's OBD-II sections (Diagnostic Trouble Codes, Powertrain Codes) for accuracy and terminology.

Likely symptoms reported by users

• Tachometer not displaying engine RPM or showing erratic readings.
• Engine cranks but may fail to start, or runs very rough if it starts.
• Check Engine light illuminated with code P0322 stored or pending.
• Intermittent no-signal condition that correlates with engine speed changes (e.g., at certain RPM ranges or under vibration/heat).
• In some cases, related ignition/engine-speed related codes may appear concurrently (e.g., P0335, P0320 family), depending on the vehicle and pattern of fault.

What this code typically points to (probable causes, with general probabilities)

• Faulty crankshaft position (CKP) sensor or ignition/distributor engine-speed input sensor (the most common cause): 40-50%
• Damaged, corroded, or loose wiring and/or connectors in the engine speed input circuit (including harness damage to CKP/PCM pins): 25-35%
• PCM/ECU fault or software issue affecting interpretation of the input signal: 5-15%
• Mechanical issues related to the sensor mount, reluctor wheel, or timing chain/belt alignment causing loss of reference signal: 5-10%
• Other sensor or wiring faults that alter reference or ground (less common, but possible in complex harnesses): 5-10%

Important: If multiple codes appear, or if there is a coexisting CKP/CMP (crank/cam) or ignition-related code, the likely fault is often in the CKP/trigger circuit or its wiring, with ECU interpretation as a secondary factor.

• General OBD-II code and powertrain code concepts: Wikipedia - OBD-II, Diagnostic Trouble Codes; OBD-II, Powertrain Codes. These sections describe how diagnostic systems monitor parameters and generate trouble codes, including the role of ignition/engine-speed inputs in powertrain diagnostics.
• Specific code description: Open Source repository entry for P0322 , which translates to This defines the code's intended meaning in a standardized form. Source: Open Source code definitions.

diagnostic flow (step-by-step)
Goal: Confirm whether the engine-speed input signal from the ignition/distributor is present, and determine whether the fault is sensory (sensor), wiring, or PCM-related.

1) Verify the DTC and data context

• Read CEC/OBD-II data stream for P0322, and review any freeze-frame data (engine RPM, ignition status, load, etc.).
• Note any concurrent codes (e.g., P0320, P0335, P0336) that might point to CKP/CMP circuits or ignition issues.
• Confirm the vehicle's make/model/year specifics, as wiring/connector configurations vary.

2) Visual and basic circuit inspection

• Inspect the CKP/ignition input sensor and its mounting area for physical damage, oil leaks, or signs of heat exposure.
• Inspect wiring harnesses and connectors in the engine-speed input circuit path: look for cracked insulation, chafed wires, bent pins, corrosion, moisture, and loose connectors.
• Check for protected wiring in areas known for flexing or close to moving parts (tension/abrasion points).

3) Power, ground, and reference checks (as applicable to the CKP/ input circuit)

• With the ignition OFF, inspect the connector pins and wiring for continuity and resistance to the expected reference/ground paths per the vehicle's service info.
• When possible, verify:
  • The reference voltage to the CKP/engine-speed sensor (often a 5V reference on a 3-wire sensor; some sensors are 2-wire with different schemes).
  • The signal circuit to the PCM: ensure continuity from the sensor to the ECU input and that the ECU is receiving the signal or recognizing its absence.
  • Ground integrity for the sensor circuit.

4) Sensor (CKP/Ignition input) functional test

• On-vehicle test with an oscilloscope or a high-quality DSO:
  • Observe the CKP/engine-speed sensor signal waveform while the engine is cranking and/or running.
  • Look for a clean, periodic waveform when the engine is turning, and specifically verify that a signal is present at cranking RPM and at idle/RPM changes.
  • If no signal is seen at expected RPM, suspect the CKP/ignition input sensor, its wiring, or the PCM input.
• Resistance/continuity test (where applicable)
  • For 3-wire CKP sensors, test sensor resistance per the vehicle's service data if such tests are specified by the OEM. (Some sensors may not have a static resistance spec; the waveform test is more definitive.)

5) Wiring harness and connector testing

• Perform continuity tests along the suspected circuit from the CKP sensor to the PCM input pin(s).
• Check for resistance to ground or to power that would indicate a short or cross-talk.
• Inspect for intermittent connections; wiggle test connectors to see if the signal reappears or disappears.
• Re-seat or replace damaged connectors if corrosion or poor contact is found.

6) Cross-check with PCM/ECU behavior

• If the sensor and wiring test OK, but the ECU still reports no signal, consider ECU fault or software limitation (rare, but possible in older platforms or after modifications).
• Check for any OEM-released service bulletins (TSBs) related to CKP input or ignition-speed circuits for your specific vehicle.

7) Reproduce and isolate

• Attempt to reproduce the fault by starting and cranking under varied conditions (cold start, warm idle, after heat soak) to determine if the signal loss is intermittent or condition-specific.
• If feasible, substitute a known-good CKP sensor (if OEM-compatible spare is available) to confirm fault isolation.

8) Repair actions (prioritized)

• If CKP sensor is faulty or its waveform is absent:
  • Replace CKP/ignition-speed sensor as per OEM guidelines.
  • Inspect the sensor mounting, reluctor ring/gear alignment, and related mechanical constraints after replacement.
• If wiring/connectors are damaged:
  • Repair or replace damaged harness sections and connectors.
  • Use OEM splices and sealed connectors if exposure to moisture is a concern.
• If PCM/ECU is suspected:
  • Update or reflash with OEM software if available.
  • Verify PCM wiring and power/ground, and consult OEM service information before replacing the ECU.

9) Final checks and validation

• After repair, re-scan for P0322 and confirm that the code clears and does not reappear.
• Use live data to verify that engine speed input is now detected by the PCM across cranking and running RPM ranges.
• Confirm there are no new codes or related CKP/CMP related codes appearing.

Safety Considerations

• Disconnect the battery or follow proper power isolation procedures before disconnecting/connecting sensors and electrical connectors.
• Use proper PPE and ensure the vehicle is securely supported if you need to access under-hood wiring.
• Avoid shorting ignition circuits and avoid high-current paths when working near ignition components.
• When using an oscilloscope or diagnostic equipment, follow the manufacturer's safety guidelines.

Sample diagnostic checklist (condensed)

• Confirm DTC and data context; review freeze-frame data.
• Visually inspect CKP/ignition input sensor area, wiring, and connectors.
• Check continuity and resistance of sensor circuits to PCM inputs; verify ground references.
• Observe sensor output waveform with an oscilloscope during cranking and idle.
• Check for intermittent connections by wiggling harness and connector and re-checking continuity.
• If sensor/wiring tests pass but signal is still missing, consider PCM/software issues; check for OEM TSBS.
• Replace CKP/ignition input sensor if no signal is confirmed; repair wiring/harness as needed.
• Re-scan and validate clearance of P0322; test drive and monitor live data to ensure signal is present across RPM range.

What to include in the repair report

• DTCs present and any related codes.
• Description of symptoms observed and freeze-frame data.
• Tests performed (visual inspection, continuity tests, oscilloscope waveform captures).
• Parts replaced or repaired (CKP sensor, connectors, wiring harness, ECU/firmware).
• Final test results including live data verification and road test outcomes.
• Any OEM service bulletins or software updates applied.

This diagnostic guide was generated using verified reference data:

• Wikipedia Technical Articles: OBD-II
• Open-Source OBD2 Data: N/A (MIT)

Content synthesized from these sources to provide accurate, real-world diagnostic guidance.

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