P1352 – Ignition Control Module Output High/Pulse Detected When Grounded Cylinder 2 (GM)

By Reinier (Contact Me)
Last Updated 2019-09-19
Automobile Repair Shop Owner

Manufacturer Specific Definitions for P1352

Table of Contents

1. What Does Code P1352 Mean?
2. Where is the P1352 sensor located?
3. What are the common causes of code P1352?
4. What are the symptoms of code P1352?
5. Get Help with P1352

What Does Code P1352 Mean?

OBD II fault code P1352 is a manufacturer specific code that is defined by car maker General Motors as “Ignition Control Module Output High/Pulse Detected When Grounded Cylinder 2”, and is set when the PCM (Powertrain Control Module) detects a short circuit to battery positive in the ignition control circuit(s) of cylinder #2.

SPECIAL NOTES:  Be aware that the information given below is a necessarily brief, and therefore, grossly simplified description of a highly complex chain of interacting events. Note that a), these events must all be completed in the correct sequence to start a modern engine, and b) that not all of the computer-controlled steps (and circuits that are required to be in perfect working order) to start a modern engine are described here. Note that the information presented here is intended to be purely somewhat illustrative of the engine starting process, and should therefore not be used in any procedures and/or attempts to diagnose and/or repair ignition-system trouble codes. 

Moreover, due to the highly complex nature of modern ignition systems, the best option is always to seek professional assistance, diagnosis, and repair of these kinds of issues to avoid serious personal injury. Note that electrocution by the extremely high currents/voltages in ignition systems can result in fatal injuries. END OF SPECIAL NOTES.

While the ICM (Ignition Control Module) has its own dedicated power supply and ground circuits that control the ignition timing during engine cranking, the PCM assumes control of the ignition timing after the engine starts. To facilitate this control function, the PCM uses input data from the CKP (Crankshaft Position Sensor), as well as input data from other sensors, such as the CMP (Camshaft Position Sensor) through circuits that include the following-

• The ignition timing trigger signal from the CKP
• The ignition timing control signal
• A low-resolution engine signal
• A medium resolution engine signal
• The camshaft position signal
• A low-reference signal

It should be noted that although each of the teeth on the reluctor ring that works in conjunction with the CKP creates a signal, the reluctor ring has many more teeth than is needed to create an ignition trigger signal for each cylinder. We need not delve into the technical reasons for this here, but suffice to say that the PCM uses the total number of signals that are created during each engine cycle in complex calculations to determine the exact moment to deliver a spark to any given cylinder, which in the case of code P1352, is cylinder #2.

In simple terms, these calculations involve dividing the total number of signals created by a factor that varies between applications and manufacturers. Nevertheless, this allows the PCM to increase the resolution of the ignition trigger signal frequency to a high degree. In practice, and in this context, “increasing the resolution” means increasing the accuracy of the ignition trigger signals’ timing.

As a practical matter though, the ICM monitors the signals from the CKP during engine cranking to determine the correct cylinder pair on which to initiate the sequence of events that control the ignition coil charge, or ramp-up time in preparation for creating and delivering ignition sparks to the pair of cylinders identified by the ICM and CKP. When the engine starts, the CKP signal and a second, high-resolution (18-×) signal pass to the ICM via a dedicated control circuit. Upon reception of both signals, the ICM passes the 18-× and a further, low-resolution 3-× signal to the PCM, which then uses these signals to assume control of the creation, timing, and delivery of ignition sparks to all the cylinders.

Thus, when a short circuit to battery positive occurs anywhere in any ignition circuit that is associated with cylinder #2, the PCM will recognize that it cannot control any aspect of the ignition on cylinder #2 effectively, and it will set code P1352 and illuminate a warning light as a result.

Where is the P1352 sensor located?

The image above shows the location (circled) of the ignition module on a General Motors 2.2L Ecotec application. Note that on other applications, such as the LS-series engines the ignition module may form part of, or be incorporated into the coil packs, while on older GM applications, the ignition module may be attached to the distributor.

Note though that the ignition module on some GM applications resembles other, unrelated modules. It is therefore recommended that proper reference to reliable service information be made to locate and identify ignition modules correctly

What are the common causes of code P1352?

The most common causes of code P1352 are much the same across most GM applications, and could include one or more of the following-

• Defective, faulty, or damaged ignition control module (Most common)
• Damaged, burnt, and/or shorted wiring/connectors in the ignition control circuit

CKP sensor defective or shorted to battery positive

What are the symptoms of code P1352?

Common symptoms of code P1352 could include one or more of the following-

• Stored trouble code and illuminated warning light
• Multiple additional codes, and particularly misfire related codes, could be present along with P1352
• Engine will almost certainly misfire, but note that in some cases, misfires may occur sporadically as the result of intermittent short or open circuits
• Idling may be rough or erratic as the result of a misfire
• Engine may be difficult to start
• Catalytic converter damage may occur if this code is not resolved in a timely manner
• Failed or failing PCM, but note that since this is a rare event, the fault must be sought elsewhere before any control module is replaced

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