help car won't spark
#1
06-06-2007, 03:32 PM
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help car won't spark
hi I have a 97 dodge neon. sohc i went to the gas station filled it up and restarted the car it started right up and idled good then just shut off. after about 20-30sec won't restart.. checked every thing. only thing that really is strange is the 12v+ power that comes off the pcm to the coil (middle wire) shows no voltage at all during all key positions but If i use a test light and stick on endto the batery positive side and one to the + side of the coil wire (middle wire) it lights up. so it looks like its grounded when it souldn't be.. what would cause this?? any info would be great. thanks Dags
#2
06-06-2007, 04:36 PM
#4
06-06-2007, 07:29 PM
RE: help car won't spark
I would recommend getting a volt/ohmmeter with at least 10,000 ohms of internal resistance. This will prevent you from damaging the pcm etc.Most digital meters will work well for this.(however this particular circuit you can use a test light on)
First, I would run a ground wire straight from the battery to your spark tester to ensure your no spark condition isn't as simple as a bad engine ground. Second, disconnect the harness from the coil packs and back probe the middle wire (use a paper clip straightened out and probe from the back of the connector this will prevent you from damaging the terminals that connect to the coil packs) Next, cycle the key to the on position. You should momentarily have 12v. You can use a test light to ground to check this circuit because it is a 12v ckt from the ASD relay (not directly connected to the pcm).If the test light doesn't momentarily light up then you have an issue with the ASD relay or associated wiring. If it does light momentarily in the on position, then crank the engine (without cycling the key off) and note the test light. If the test light momentarily lights(flashes) during cranking then the pcm is not receiving a crankshaft position sensor signal. If test light doesn't flash then unplug the crankshaft position sensor (CKP). turn key off then on, wait for it to flash momentarily, then crank and observe test light. if it momentarily flashes then CKP is shorted and must be replaced. If it doesn't flash then the problem lies in the 8volt supply to the CKP/CMP (camshaft position sensor) or the CMP output or ground circuits. I would read/perform this test several times to ensure the accuracy of your testing. If you have dissassembled anything else on the car return it to its normal state before performing this test. Good luck!!!!
First, I would run a ground wire straight from the battery to your spark tester to ensure your no spark condition isn't as simple as a bad engine ground. Second, disconnect the harness from the coil packs and back probe the middle wire (use a paper clip straightened out and probe from the back of the connector this will prevent you from damaging the terminals that connect to the coil packs) Next, cycle the key to the on position. You should momentarily have 12v. You can use a test light to ground to check this circuit because it is a 12v ckt from the ASD relay (not directly connected to the pcm).If the test light doesn't momentarily light up then you have an issue with the ASD relay or associated wiring. If it does light momentarily in the on position, then crank the engine (without cycling the key off) and note the test light. If the test light momentarily lights(flashes) during cranking then the pcm is not receiving a crankshaft position sensor signal. If test light doesn't flash then unplug the crankshaft position sensor (CKP). turn key off then on, wait for it to flash momentarily, then crank and observe test light. if it momentarily flashes then CKP is shorted and must be replaced. If it doesn't flash then the problem lies in the 8volt supply to the CKP/CMP (camshaft position sensor) or the CMP output or ground circuits. I would read/perform this test several times to ensure the accuracy of your testing. If you have dissassembled anything else on the car return it to its normal state before performing this test. Good luck!!!!