QuestionHi my mom just called me and she said her car told her that the electrical system is malfunctioning and turns over but won't start. She just got the car from a friend it was a gift maybe a headache is more like it lol. We are back yard mech and she lives 10 miles from me so I have the computer to try and find an answer and your the expert.
AnswerHi Preston,
It is good you have some skills because I think you will be able to get the car going again. The first thing to do is check to see if you have any spark. Just remove the center wire from the distributor cap and hold the tip 1/4" from the cylinder head and see if you get a spark to jump the gap when a helper tries to start it. If you get spark, try moving the wire away slowly during a 5 second crank and verify that there is no arcing at the spark coil wire tower. It that is o.k. then replace the wire in the distributor and check whether you are getting spark at one of the spark plug connector caps by using a spare plug with the threaded shell grounded, of a insulated handle screwdrive inserted in the cap with the shaft held 1/4" from the cylinder head while cranking. Those tests will verify the rotor and distrubutor cap are also good. If they are then we have to consider fuel system issues.
If you get no spark at all then you need to check for 12V at the + post of the spark coil when the engine is cranked. If you don't get 12v at all then the autoshutdown relay may be faulty or even the engine controller but we can test that later. If you get 12v for 1-2 seconds then there is a problem with the hall effect ignition timing sensor circuit in the distributor, and if you get 12v for 5 seconds of cranking then it is either the spark coil, the engine logic module or the wiring between the two. More testing is then needed.
One very useful thing to do: Check for coded fault codes.
The fault codes are stored in the engine controller memory for readout. Try using the ignition key: turn it "on-off-on-off-on" and leave it "on" (doing this quickly, no longer than 5 seconds). Then watch the 'check engine' light to begin flashing, then pause, flashing, pause, etc. Count the number of flashes before each pause and keep track of the numbers. Repeat the readout and verify the counts are correct. Then group them in pairs in the order that they came out, thus forming two digit numbers. You may notice that the pause is shorter between the digits of a given number, and longer between the numbers themselves. By the way, 55 will be the last number (two groups of 5 flashes each) and that is the code for "end of readout". The code for the Hall sensor for ignition timing located in the distributor will be the first one to read out as it in the number 11 (one flash-pause-one flash-pause). The autoshutdown relay circuit fault is code 42, but the ASD relay itself could be bad without giving that code.
If you get 12V for the full 5 seconds of cranking then I would suspect the coil has gone bad (or the wiring from the - post of the coil to the controller is bad.)
The most likely cause of a no start is the Hall sensor, but if you have a voltmeter verify that the 12V drops away after 1-2 seconds of cranking, and/or that you get a code 11. The sensor is easy to replace and costs about $40 if you have the 4 cyl. engine.
If you need to send a follow-up question, tell me which engine you have so that I can be specific with any advice.
Roland
