What this code means
P0352 means the PCM may be detecting a problem with the primary control circuit for ignition coil 2.
What the vehicle may do
- The vehicle may run rough or misfire.
- The MIL can illuminate.
- The engine may have reduced performance or an uneven idle.
Possible fault areas
- A possible feed-side circuit issue may be involved.
- The coil 2 control circuit can have a wiring or connection problem.
- The ignition coil, spark plug path, or coil boot may be involved.
- The PCM driver may be involved after the circuit and coil checks are completed.
Diagnostic path
Opening and initial confirmation
On this Ram 1500 with the 5.7 Hemi, P0352 is an ignition coil 2 primary circuit fault. In plain language, the PCM may not be seeing the expected current on the coil 2 control side. The truck may run rough, misfire, lose power, or turn the MIL on, and the possible fault areas can include the coil feed, the coil control circuit, the coil itself, connector problems, or the PCM driver. Before going deep, start with the basic pre-diagnostic checks. Then read and record the codes and the captured operating data from every module, save the scan report and related data, clear the codes, turn the ignition off for a minimum of 10.0 seconds, turn it back on, and operate the vehicle under the conditions that set the fault. If P0352 does not return, treat it as an intermittent condition. If it does return, continue the circuit path. The monitor runs continuously with the ignition on, and this code sets when the PCM detects the Ignition Coil 2 signal circuit current is less than, or equal to, 0.0 amps for at least 1.2 seconds. The MIL will illuminate.
Check code context, then load-test the feed
Next, look at the recorded codes before you isolate the coil circuit. If an ASD-related code is present, diagnose that first because it can affect the feed side of this test. If there are no ASD concerns, move to the relay output feed for the ignition coil. Disconnect the coil connector to isolate the 12.0 volt supply circuit, connect the load test tool between that feed and battery ground or a known good chassis ground, and make sure the circuit is actually powered. For an ignition feed, the ignition has to be on; for a relay output, the relay has to be energized. Do not rely on a high-impedance light for this decision. A 3156 bulb has approximately 6.0 Ohms of resistance and draws approximately 2.0 amps of current, while a high-impedance test light may draw less than 0.1 amps. The point is to put enough load on the circuit to expose resistance. More than approximately 0.75 amps is the guidance here. If the bulb is bright, the feed is good enough to move on. If it is not bright, repair the 12.0 volt circuit for an open or high resistance. If the fuse is open, check that circuit for a short to ground, then verify the repair and confirm the code stays gone.
Check coil 2 control operation
Once the feed side passes the load test, check the Coil 2 control circuit. Use a 12-volt test light connected to a 12.0 volt source, probe the Coil 2 control circuit at the ignition coil harness connector, and crank the engine for 5.0 seconds while watching the light. Stay clear of the fan, belts, pulleys, and any moving parts while the engine is cranking or running. If the light is brightly blinking, the driver is switching the circuit, so move to the spark plug and secondary-side checks. If the light is on constantly, go after a short to ground on the control circuit. If the light stays off constantly, go after an open or high resistance on the control circuit.
If the control signal blinks, inspect the spark plug path
If the control circuit is blinking normally, turn the ignition off and inspect the spark plug or plugs involved. Look for cracks, carbon tracking, foreign material, gap size out of specification, and a loose or broken electrode. If one of those plug conditions is present, replace the spark plug. If carbon tracking is found on the plug, inspect the ignition coil boot for damage and replace the boot if necessary. If none of those plug conditions are present, the path calls for replacing the ignition coil and spark plug, then verifying the repair and confirming the code stays gone.
If the control signal is stuck on or stuck off, test the control wire
If the test light was on constantly, isolate the Coil 2 control circuit and check it for a short to ground. The ignition must be off for a continuity-to-ground test. Disconnect the ECU side and every connector that contains the circuit being tested, use the wiring path to follow the circuit, put the negative DVOM lead on a known good ground, and probe the control circuit from the component connector. There should be no continuity between ground and the circuit. If continuity is present, repair the short to ground, then verify the repair. If continuity is not present, move to the coil and PCM driver check. If the test light was off constantly, check that same control circuit for an open or high resistance. The ignition must be off for continuity testing. Disconnect the ECU and the component connector, measure the DVOM lead resistance first, then measure the control circuit from the coil connector to the GPEC adaptor. If you have to work at the PCM connector, use the GPEC Diagnostic Adaptor; do not probe the PCM harness connectors because that can damage the terminals and cause poor terminal-to-pin contact. The circuit needs to be below 3.0 Ohms. The adaptor can add up to 1.5 Ohms of resistance to the circuit. If the resistance is not below 3.0 Ohms, repair the circuit for an open or high resistance, then verify the repair. If it is below 3.0 Ohms, continue.
Determine whether the coil damaged the PCM driver
Before condemning the PCM, make sure the ignition coil did not cause the driver failure. An internally shorted or damaged secondary coil circuit may be the cause of a PCM coil driver failure, so do not replace the PCM without checking this. Remove the ignition coil controlled by the driver that set P0352 and install that coil in another coil location that did not have a fault against it. Turn the ignition on, clear the codes, then start and run the engine for up to one minute. If the engine will not start, crank the engine three times for 10 seconds. Read the codes again. If a correlating fault sets for the new coil location, replace the ignition coil and replace and program the PCM, then verify the repair. If the fault does not follow the coil, continue to connector and harness checks.
Connector checks and final verification
At the end of the path, check for applicable service bulletins, then inspect the PCM connectors, any related in-line connectors, and the ignition coil connector. Look closely for poor installation, damaged locks, corrosion, water intrusion, seal damage, bent terminals, overheating from a poor connection, pushed-back terminals, spread terminals, and weak terminal tension. Repair any conditions you find. Reconnect everything fully, make sure the locks are engaged, clear the codes, and operate the vehicle under the same monitored conditions. If P0352 returns after those connection checks, replace and program the PCM, then verify the repair. If it does not return, the wiring or poor connection problem has been repaired. Takeaway: prove the feed, prove the driver command, prove the control wire, and do not skip the coil-to-PCM driver check before making the final call. For more diagnostic training, visit stepdiagnostics.com.
Final check
P0352 is often best diagnosed by confirming the fault, checking the feed, checking control operation, testing the control circuit, and only then making the final PCM decision.
For more guided automotive diagnostics, visit STEP Diagnostics.
