P0374 Timing Reference High Resolution Signal A No Pulses
OBD-II Trouble Code Technical Description
Timing Reference High Resolution Signal A No Pulses
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code, which means it applies to OBD-II equipped vehicles which have an engine position sensor (Chevrolet, GMC, Ford, Dodge, BMW, etc.). Although generic, the exact repair steps may vary depending on make/model.
The powertrain control module (PCM) requires a timing reference signal to determine engine speed and position. This is accomplished by means of an engine position sensor, such as a crankshaft, camshaft or fuel pump position sensor.
The PCM uses this information to determine one or more of the following: fuel injector control, ignition timing and misfire diagnostics. There are two basic types of engine positions sensors: Hall-Effect and permanent magnet.
Both types of sensors are triggered by a wheel or disc mounted close to the sensor. Typical wheel/disc mounting locations include the engine position, injection pump, harmonic balancer and distributor shaft. When triggered, the sensor produces a return signal which is sent back to the PCM.
Hall-Effect crank position sensors have three wires: reference (power), signal, and ground. The sensor receives a reference voltage (usually 5-volts) from the PCM, and is triggered by a reluctor wheel. The sensor then sends a corresponding digital return signal back to the PCM. Permanent magnet (PM) sensors produce their own AC voltage based on their proximity to a rotating reluctor wheel. This voltage signal is sent back to the PCM where it is converted to a digital signal by an internal analog to digital converter.In the codes outlined in this article, the "A" indicates the problem is with a portion of the system circuit, instead of a particular symptom or component.
A code P0374 is set when the PCM detects the engine position sensor "A" signal has no pulses.
Related timing reference signal A trouble codes include:
P0370 Timing Reference High Resolution Signal A Malfunction P0371 Timing Reference High Resolution Signal A Too Many Pulses P0372 Timing Reference High Resolution Signal A Too Few Pulses P0373 Timing Reference High Resolution Signal A Intermittent/Erratic PulsesCode Severity & Symptoms
The severity of these codes is moderate to severe. Symptoms of a P0374 engine code may include:
Illuminate check engine light Hard starting/no starting Poor engine performanceCauses
Possible causes for this P0374 code include:
Faulty sensor Wiring problems Reluctor wheel damage Contaminated oil Faulty PCMDiagnostic and Repair Procedures
Begin by visually inspecting the engine position sensor and the corresponding wiring. Look for loose connections, damaged wiring, etc. If damage is found, repair as necessary, clear the code and see if it returns. Also, check the engine for any metal particulates that may affect sensor operation.
Next, check for technical service bulletins (TSBs) regarding the issue. If nothing is found, move forward to step by step diagnosis of the system.
The following is a generalized procedure, as testing for this code varies between vehicles. To accurately test the system, you'll want to refer to the manufacture's diagnostic flow chart. Test procedures also depend on the type of sensor found in your vehicle.
Check the sensor
Hall-Effect sensor: use a digital multimeter set to DC volts and a back-probe test lead to ensure the sensor is producing a signal voltage. Connect one meter lead to the sensor signal wire and the other to ground. Have an assistant rotate the engine by tapping the ignition key (don't start the engine); the voltage reading should fluctuate between 0 volts and reference voltage. If available, you can also use an o
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