P1320 – Ignition Signal

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By Stephen Darby (Contact Me)
Last Updated 2016-12-19
ASE Master Tech
CodeFault LocationProbable Cause
P1320 P1320 – Ignition Signal
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Manufacturer Specific Definitions for P1320

MakeFault Location
AudiKnock Sensor 2 Circuit Short To Ground
BuickIC Module 4X Reference Circuit Intermittent No Pulses
CadillacIgnition control module (ICM) -4X reference circuit, intermittent
ChevroletIC Module 4X Reference Circuit Intermittent No Pulses
DaewooCrankshaft position (CKP) sensor- signal adaptation at limit
GmIC Module 4X Reference Circuit Intermittent No Pulses
InfinitiIgnition signal – circuit malfunction
LexusIgnition control – cylinder No.5 – circuit malfunction
MercuryIgnition check signal misSing
MitsubishiIgnition timing – cold start emission control
NissanIgnition signal – circuit malfunction
OldsmobileIgnition control module (ICM) -4X reference circuit, intermittent
SaabIgnition coils, bank 2 – no supply voltage
SuzukiCrankshaft Segment Malfunction
ToyotaIgnition control - cylinder No. 5 - circuit malfunction
VolvoIntake air temperature {IAT) sensor- signal low
VolkswagenKnock Sensor 2 Circuit Short To Ground

Table of Contents

  1. What Does Code P1320 Mean?
  2. What are the common causes of code P1320?
  3. What are the symptoms of code P1320?
  4. How do you troubleshoot code P1320?
  5. Codes Related to P1320
  6. Get Help with P1320

What Does Code P1320 Mean?

In the past, when I have been tasked with diagnosing a stored code P1320, it has meant that the powertrain control module (PCM) has detected a malfunction in the ignition system primary voltage signal. Primary voltage typically refers to circuits which deliver voltage to the ignition coils, coil packs, or coil igniters and not the high-intensity spark plug leads that connect the coils to the spark plugs.

In the coil-over-plug, distributor-less ignition system, each cylinder is outfitted with its own ignition coil. Individual coils are attached to the spark plugs with a short plug wire or silicon boot. Standard operation consists of a constant supply of battery voltage and a ground pulse from the PCM (applied to a tightly wound induction coil) to create the high-intensity spark (many thousands of volts) that is required to fire the spark plug of each cylinder.





Ignition systems which utilize coil packs operate in a similar manner but multiple spark plugs are fired from a single coil pack (with multiple towers) which fires multiple cylinders in sequential order. This type of system typically uses high tension spark plug leads, which are much longer, to transfer high-intensity spark from the coil pack towers to each spark plug at the appropriate time.

Whatever type of ignition system with which the vehicle in question is equipped, spark timing and function are controlled by the PCM. The PCM uses input signals from the crankshaft position sensor and camshaft position sensor/s to map spark timing. With the ignition switch on, the coils/coil pack are supplied a constant supply of battery voltage. The ignition coil releases a high-intensity spark when it receives a ground pulse from the PCM.

If the PCM detects any inconsistencies in completion of the ignition coil circuits, when the ground pulse is applied, a code P1320 will be stored and a malfunction indicator lamp (MIL) may be illuminated.

What are the common causes of code P1320?

  • Open or shorted primary/secondary circuits
  • Defective ignition coils or coil pack/s
  • Defective crankshaft/camshaft position sensor or circuits
  • Bad ignition system relay
  • Blown fuses or fusible links
  • Faulty PCM or a PCM programming error

What are the symptoms of code P1320?

  • Drivability issues, including one or more ignition misfires
  • Diminished engine performance
  • Poor fuel efficiency
  • Cylinder misfire codes will likely accompany a code P1320

How do you troubleshoot code P1320?

Gaining access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable vehicle information source, such as ALL DATA (DIY) will be necessary to diagnose a code P1320. An oscilloscope may also prove helpful if the problem is related to the crankshaft or camshaft sensor/s.

A great place to begin diagnosis of a code P1320 is a visual inspection of all ignition coil/pack wiring and connectors. Broken electrical connectors at the ignition coils or coil packs is common. I would also check for wiring that is burned, broken, or corroded. Rodent damaged wiring is something that I have personally found to be the cause of a code P1320, in several customer cars. Corrosion in ignition coil electrical connector faces is also relatively common.

Next, I’d connect the scanner to the vehicle diagnostic port and retrieve all stored codes and freeze frame data. I have found it beneficial to record this information for later. Now, I like to clear the codes and test-drive the vehicle to see if the P1320 is reset.

Take advantage of your vehicle information source to search technical service bulletins (TSB) that may help with your diagnosis. TSBs with matching symptoms and codes can be helpful because they contain valuable diagnostic tips.

Crankshaft and camshaft position sensor codes should be diagnosed and repaired prior to attempting to diagnose a P1320.

The presence of cylinder specific ignition coil primary/secondary circuit codes may help you to pin point the defective circuit or coil/pack. If there are no cylinder specific codes present, you will need to find out which coil, coil pack, or circuit is malfunctioning before continuing your diagnosis. This can be accomplished by using the DVOM to test the coils/coil packs for the correct level of Hertz, when high-intensity spark is emitted, but I prefer a much simpler method. With the engine running and the parking brake set, have an assistant sit in the driver’s seat. With the hood raised, position yourself near the engine, have your assistant press the brake firmly to the floor, place the shifter in drive, and depress the accelerator pedal slightly but gradually. When the engine begins to misfire, have your assistant hold the accelerator pedal in that position, while you systematically remove each spark plug wire/boot from each respective spark plug. You may also unplug each coil pack electrical connector to avoid being shocked by the more than 50,000-volts of high-intensity spark but where’s the fun in that? Once you discover a coil/coil pack tower that makes no difference in engine RPM, when the plug wire/boot is removed from the spark plug; you have found the cylinder number of the coil/coil pack tower at fault. You will probably notice that the level of high-intensity spark emitted from the malfunctioning coil/coil pack tower is significantly less (and/or a different color) than those which are functioning properly. Clear all codes after performing this type of testing.





With the ignition switch on, use the DVOM to test for battery voltage at the coil/pack connector after you have located the coil/pack in question. If there is no voltage present, suspect a blown fuses or defective relay. Keep in mind that blown fuses are a reaction to an electrical short and not the source of a malfunction.

Disconnect all related control modules and use the DVOM to probe individual circuits for continuity and resistance, if all fuses and relays are good.

If the voltage signal is present at the ignition coil/pack, I would test the coil connector for a ground pulse from the PCM. If no ground pulse is present, when the engine is cranked or running, suspect a defective PCM.

  • P0300 Random/Multiple Cylinder Misfire Detected
  • P0301 Cylinder 1 Misfire Detected
  • P0302 Cylinder 2 Misfire Detected
  • P0303 Cylinder 3 Misfire Detected
  • P0304 Cylinder 4 Misfire Detected
  • P0305 Cylinder 5 Misfire Detected
  • P0306 Cylinder 6 Misfire Detected
  • P0307 Cylinder 7 Misfire Detected
  • P0308 Cylinder 8 Misfire Detected
  • P0309 Cylinder 9 Misfire Detected
  • P0310 Cylinder 10 Misfire Detected
  • P0311 Cylinder 11 Misfire Detected
  • P0312 Cylinder 12 Misfire Detected
  • P0316 Misfire Detected On Startup (First 1000 Revolutions)
    P0335 Crankshaft Position Sensor A Circuit Malfunction
  • P0336 Crankshaft Position Sensor A Circuit Range/Performance
  • P0337 Crankshaft Position Sensor A Circuit Low Input
  • P0338 Crankshaft Position Sensor A Circuit High Input
  • P0339 Crankshaft Position Sensor A Circuit Intermittent

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