P0322 on 1994-1999 Cadillac DeVille: Ignition Speed Input Circuit Fixes

What's Unique About the 1994-1999 Cadillac DeVille

The 1993-1999 Northstar engine uses a unique ignition system with two crankshaft position sensors (CKP A and CKP B) and one camshaft position sensor that feed data to a dedicated Ignition Control Module (ICM). The ICM processes these signals before sending a final engine speed signal to the PCM. This means a P0322 code can be caused not just by the sensors themselves, but also by a failure of the ICM, which is a common point of failure on this platform. The two CKP sensors read a reluctor ring on the crankshaft that has 24 evenly spaced notches and 8 unevenly spaced notches to provide precise position information.

Symptoms You May Notice

• Engine cranks but will not start
• Engine stalls unexpectedly, especially when hot
• Intermittent stalling at idle or low speeds
• Check Engine Light is on
• Lack of power and poor acceleration
• Tachometer may not work or behave erratically
• Hard starting followed by rough running

Most Likely Causes

1. Failed Crankshaft Position (CKP) Sensor(s) 🔴 High Probability → Shop Engine Crankshaft Position Sensor The Northstar engine has two CKP sensors located in a high-heat area behind the oil filter adapter housing, making them prone to failure over time from heat soak and vibration. Oil leaks from the housing can also contaminate the sensors and their connectors.
   How to confirm: Use a scan tool to monitor engine RPM data while cranking. If RPM is 0, the sensors or their circuit are faulty. Test the sensor's resistance and output signal with a multimeter or oscilloscope. Visually inspect for oil contamination on the sensor connectors.
   Typical fix: Replace both crankshaft position sensors as a pair. The sensors are often distinguished by connector color (one black, one gray). Access requires removing the oil filter and the oil filter adapter housing. 🎬 Watch: Step-by-step Northstar crankshaft sensor replacement
   Est. part cost: $40-$100 for a pair of aftermarket sensors
2. Failed Ignition Control Module (ICM) 🟡 Medium Probability The ICM processes the signals from the crank and cam sensors before sending them to the PCM. It's a known failure point on this platform, and its failure will cut the signal to the PCM, triggering P0322. The module contains electronics that can fail from heat and age.
   How to confirm: If the CKP sensors are confirmed to be sending a signal, but the PCM is not receiving it, the ICM is the likely culprit. This requires testing the input and output signals at the ICM connector with a multimeter or oscilloscope.
   Typical fix: Replace the Ignition Control Module. It is typically located on the front of the engine, often integrated with the coil packs.
   Est. part cost: $70-$150
3. Damaged Wiring or Connectors 🟡 Medium Probability Engine heat can make wiring and plastic connectors brittle over time, leading to cracks, corrosion, or poor connections. The harness to the CKP sensors is particularly vulnerable due to its location near hot engine and exhaust components.
   How to confirm: Visually inspect the wiring harnesses for the crankshaft position sensors and the ignition control module. Look for any signs of damage, melting, or corrosion. Perform a continuity test on the signal and ground wires.
   Typical fix: Repair or replace the damaged section of the wiring harness or the connector.
   Est. part cost: $10-$50 for repair materials

Rare But Worth Checking

• Failed Camshaft Position (CMP) Sensor: While the code points to the engine speed (crankshaft) circuit, a faulty camshaft position sensor can sometimes cause related ignition system issues on the Northstar engine.
• Weak Battery or Charging System Issue: → Shop Vehicle Battery A low battery voltage during cranking can sometimes prevent the sensors from generating a strong enough signal for the PCM to read, triggering the code.
• Failed Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is very rare, but the PCM itself can fail. This should only be considered after all other possibilities (sensors, wiring, ICM) have been exhaustively ruled out.

Diagnosis Steps

1. Connect an OBD-II scanner and check for any other stored codes.
2. Monitor the live data for Engine RPM while cranking the engine. If it reads 0, there is no signal from the crankshaft sensors.
3. Visually inspect the wiring and connectors for the crankshaft position sensors (located behind the oil filter housing) and the Ignition Control Module (ICM). Look for any signs of damage, corrosion, or loose connections.
4. If the wiring appears okay, test the crankshaft position sensors. You can check their resistance with a multimeter or use an oscilloscope to check for a signal while cranking. The two sensors are often referred to as CKP A and CKP B.
5. To access the CKP sensors, you will need to raise the vehicle, remove the oil filter, and then unbolt the oil filter adapter housing (typically two 10mm bolts).
6. If the sensors are producing a signal, the next step is to check the input and output signals at the Ignition Control Module to determine if it is faulty.
7. If the ICM is receiving a signal from the sensors but not sending one to the PCM, the ICM needs to be replaced.
8. If all sensors, wiring, and the ICM are confirmed to be good, the final step would be to diagnose a potential issue with the PCM, though this is highly unlikely.

Parts You'll Likely Need

• Crankshaft Position Sensor (OEM #ACDelco 213-345) — These sensors are the primary source of the engine speed signal and are a very common failure item due to engine heat. It is highly recommended to replace both at the same time.
  Trusted brands: ACDelco, Delphi, Standard Motor Products, Dorman
  OEM price range: $50-$80 each
  Aftermarket price range: $20-$50 each
• Ignition Control Module (OEM #ACDelco D1998A (replaces GM 19178832)) — The ICM is a critical link between the sensors and the PCM on the Northstar engine and is a known point of failure that directly causes a P0322 code.
  Trusted brands: ACDelco, Standard Motor Products
  OEM price range: $150-$250
  Aftermarket price range: $70-$150

Related Codes That Often Appear With This One

• P0300 — A random misfire code can be logged if the engine runs intermittently with an erratic crank signal before it fails completely.
• P0372 — Timing Reference High Resolution Signal A No Pulses. This is a more specific GM code that can accompany P0322, pointing directly to an issue with the crankshaft position sensor circuit.

Platform-Specific Known Issues

• Accessing the two crankshaft position sensors is difficult. They are located behind the oil filter adapter housing, which must be removed. This can be a messy job due to oil spillage. A video guide for a similar Northstar engine shows the process: https://www.youtube.com/watch?v=5z4_jwPSnBw

Mechanic-Grade Diagnostic Values

• Crankshaft Position Sensor (Magnetic/VR Type) AC Voltage Output — expected: ~0.2–2.0 VAC (peak). Failure: No AC voltage signal, or a flat line on an oscilloscope while the engine is cranking, indicates a failed sensor or a problem with the reluctor ring/wiring.
• Sensor Reference Voltage at Connector — expected: 5V or 12V (depending on system). Failure: Voltage below the specified reference (e.g., under 4.5V for a 5V reference) suggests a power supply problem from the PCM or a wiring issue.

Wiring & Ground Locations

• G101 — Located at the left front of the engine, on the lower block.. This is a primary ground point for the Engine Control Module (ECM) and Transmission Control Module (TCM). A poor connection here can cause erratic behavior and fault codes for various sensors, including the crankshaft position sensors. 🎬 Watch: How a bad ground causes a no-start

OEM Part Supersession History

• GM 10489422 → ACDelco D1998A / GM 19245557 — Standard part number update and consolidation over time.

Model Year Variations Within This Range

• 1993-1994: Engines have a knock sensor below the firewall-side cylinder head and feature cast aluminum intake manifolds.
• 1995: Switched to a thermoplastic intake manifold, which changed how the EGR system feeds into the cylinders.
• 1996-1999: Received a new block casting. The knock sensor was relocated to under the intake manifold. The harmonic balancer bolt size was also changed.
• 2000+: The ignition system was significantly changed to a coil-on-plug design, eliminating the ICM and coil packs used in the 1994-1999 models. Parts are not interchangeable.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Head Gasket Failure (Pulled Head Bolts) 🔴 High — Very common, typically between 60,000 and 100,000 miles. The issue is not the gasket itself, but the fine-threaded head bolts pulling out of the aluminum block.
• Excessive Oil Consumption 🟠 Medium — Common on pre-2000 models due to carbon buildup on piston rings. Consumption of a quart of oil every 500-1,000 miles is not unusual.
• Rear Main Seal & Other Oil Leaks 🟠 Medium — Widespread issue due to seal design on pre-2000 models. Leaks from the oil pan and valve covers are also common.
• Difficult Starter Motor Replacement 🟠 Medium — The starter motor is located under the intake manifold in the 'V' of the engine, making replacement a labor-intensive job requiring 3-4+ hours.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: Used parts like the Ignition Control Module (ICM) can be a cost-effective option if sourced from a reputable seller with a warranty. Given the high cost of a new OEM module, a tested used unit from a low-mileage vehicle is a reasonable choice.

Donor-vehicle mileage cap: roughly under 100000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For an ICM, check for any cracks in the housing or corrosion on the electrical pins.
• For wiring harnesses, ensure the plastic connectors are not brittle or cracked and that there are no signs of previous repairs or melted insulation.
• Verify the donor vehicle was not in a front-end collision that could have damaged engine-mounted electronics.

OEM-only on this vehicle (don't cheap out):

• Crankshaft Position Sensors: Due to their critical function and high-heat location, using new, high-quality OEM (ACDelco) or reputable aftermarket sensors is strongly recommended to avoid repeat failures.

Aftermarket brands forum-validated for this vehicle:

• ACDelco (OEM)
• Delphi
• Standard Motor Products (SMP)
• Bosch

Brands owners have reported issues with on this vehicle:

• Generic, unbranded "white-box" sensors sold on auction sites are known for high failure rates and should be avoided for critical components like crankshaft sensors.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0300 — Random misfire code that may trigger alongside P0322 due to the rough running and lack of power caused by intermittent CKP or ICM signal loss.
• P0335 — Crankshaft Position Sensor A Circuit malfunction; directly related to the dual-sensor setup on the Northstar engine where P0322 indicates a lack of signal.
• P0336 — Crankshaft Position Sensor A Circuit Range/Performance; often occurs when the sensors are failing due to heat soak or oil contamination.
• P0340 — Camshaft Position Sensor Circuit malfunction; the ICM processes both cam and crank signals before sending data to the PCM.
• P1350 — Ignition Control System signal failure; specifically related to the ICM's ability to process and relay timing signals to the PCM on GM Northstar platforms.

Frequently Asked Questions