AutoCodes – GMC – P1374 GMC

P1374 GMC Code - 3X Reference Circuit

Quick Answer

The 3X reference signal is produced by the Ignition Control Module (ICM). Common causes include Faulty Crankshaft Position (CKP) Sensor, Crankshaft Position (CKP) Sensor harness is open or shorted, Crankshaft Position (CKP) Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1374 GMC indicates 3X Reference Circuit.
Common causes: Common causes include Faulty Crankshaft Position (CKP) Sensor, Crankshaft Position (CKP) Sensor harness is open or shorted, Crankshaft Position (CKP) Sensor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 4,993

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 16, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
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Code P1374 GMC Description

The 3X reference signal is produced by the Ignition Control Module (ICM). The ICM calculates the 3X reference signal by dividing the Crankshaft Position (CKP) sensor 18X pulses by 3. This calculation is performed while the engine is running, and while the CKP sync pulses are being received. The Powertrain Control Module (PCM) uses the following information:
- The 3X reference signal in order to calculate the engine RPM, and the CKP at engine speeds above 1,200 RPM
- The pulses on the circuit in order to initiate injector pulses
- A constant monitoring of the number of pulses on the 3X reference circuit
- A comparison to the number of 3X reference pulses to the number of 18 X reference pulses and CAM signal pulses being received

OBDII Code P1374 GMC - 3X Reference Circuit - AutoCodes.com — P1374 GMC Code - 3X Reference Circuit

What does this mean?

What are the Possible Causes of the DTC P1374 GMC?

Faulty Crankshaft Position (CKP) Sensor
Crankshaft Position (CKP) Sensor harness is open or shorted
Crankshaft Position (CKP) Sensor circuit poor electrical connection
Faulty Ignition Control Module

How to Fix the DTC P1374 GMC?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1374 GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.