Ignition code repair dealing with P0351 codes stand for ignition problem in the primary circuit. This fault can cause a misfire accompanied by the flashing of the mil (malfunction indicator in the dash) light in your dash panel. On most vehicles, this problem is fixed by replacing the ignition coil and their wiring connections to the engine computer. In older engines like late 90s vehicles, it mostly deals with ICM. Ignition control module (ICM) is used by your engine computer to gather the speed signal in calculating the timing of the spark. If that signal is interrupted or out of range, a fault code will be set up by the ecm. I would like to add that when dealing with ICM, we are talking about 2 basic ignition systems such as the one associated with engines having distributor and without distributor (distributorless). On the distributor system, the speed signal comes from the rotating distributor shaft monitored by the pick up coil. On system without distributor, the speed signal is gathered by the crank sensor which monitors the crankshaft rotation.
The primary circuit of the ignition coil operates on battery voltage whereas as the secondary circuit the carries the high voltage such as the one that fires your cylinder (high voltage spark). The primary circuit includes the crank sensor or equivalent pick up coil, part of the distributor and all circuits that collects the speed signal for the engine computer. In severe cases, if the ignition module completely fails, it can cause no spark. To test, check the ICM for power supply and do the same for ignition coil. Using a test light, probe the negative terminal of the ignition coil while cranking. It should blink while the engine is being crank. If the engine has no distributor, replacing the crank sensor should fix this code.
There are many types of ignition system being used in different engines and to be able to fix this code, one has to get the symptoms of the ignition problem so you can analyze and identify the fix using ATS database. Example: an ignition control module failure means replacing the distributor on one type of engine but it could be a defective crank sensor on the engine without the distributor. Also, with the correct engine designation, the correct ignition wiring could be used to troubleshoot the ignition problem.
Some quick examples of ignition code repair are:
P0351 code for 2003 Toyota is a bad ignition coil and its wiring connections. If this does not fix the problem, check the terminals for the ignition coils pins to the ecm. On some occasions, the ecm might have to be replaced also (try tapping the ecm if it would trigger the symptom).
P0351 on 1997 Dodge Neon is almost always a problem on the crank sensor. Check the crank sensor wires which can be brittle which indicates internal wiring failure. If confirmed, replace both the crank sensor and the defective wires.