my 96 cherokee died 2 weeks ago and came up with code p0351 primary/secondaryignition circuit. i replaced the coil and fuel filter but still occasionaly has a hiccup andsometimes will cut off completely either coming to life after few seconds or sometimeshaving to pull off the road and wait a few minutes to start and drive again. help it'sdriving me nuts
Country: United StatesMake: JeepModel: cherokkeYear: 1996Engine: 4.0
new coil and fuel filter truck has 150k on it
Hello and welcome to JustAnswer!While the problem could be caused by an open circuit in the wiring to either circuit going to the coil, this is almost always caused by a failed powertrain control module (PCM). What happens is the coil driver circuit in the PCM will go down, you lose spark, and the P0351 sets. Sometimes they will come back after a few seconds, often with a severe exhaust backfire lighting off the fuel that was injected and went out the tailpipe while there was no spark.The first thing I would recommend is start the engine and wiggle test the PCM connectors. Often you can move the connectors enough to move the circuit board inside and it will either cause the engine to miss or die completely. If moving the connectors has an effect on the way it runs then the PCM will need to be replaced.If the wiggle test doesn't have any effect then the safest thing to do would be to load test the coil driver and ASD feed wires to the coil, and if they are ok and the coil is good then the PCM will need to be replaced.
how do i load test the driver and asd feed wires to the coil
You would need a headlamp or fog lamp bulb and a couple jumper wires.For the ASD feed you would jump the ASD relay to keep it powered up. Remove the relay and jump between pins 87 and 30. Unplug the coil and find the dark green/black wire, insert a paperclip into the terminal. Attach the end of a jumper wire to the paperclip, the other end of the jumper wire will go to one terminal of the light bulb. A second jumper wire will go from the other bulb terminal and the other end to ground. The light bulb should light up just as brightly as if you connected it directly to the battery. If it's dim or will flicker while wiggle testing the wiring harness then you have a wiring issue.The injector driver circuit is nearly the same. You would attach your bulb and jumper wire setup to the other terminal in the coil connector and the end of the second jumper wire will go to battery positive. At the PCM you would unplug it and jump the coil driver wire to ground to light the bulb and wiggle test the harness.
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