Chrysler Repair/'95 new yorker: no spark
QUESTION: I have no spark, engine cranks but doesn't start. put new coil and crank shaft sensor in. I don't get any codes coming up (thanks to another story you did now i know how to get codes). the fuses and relays are good. the voltage in the orange and green wire varies when the key is in start position. Just for a second then to zero.
ANSWER: Hi Rebecca,
The 12V on the orange/green wire is there for about a second after you turn the key to the run position. That is normal. Then when you start to crank it the voltage should reappear and be there until the engine starts and of course continues thereafter. But if it doesn't appear when you start cranking, for more than a second, then there is likely a problem with the crank or cam shaft rotational sensor not functioning. Measure the voltage coming from the sensors while you rotate the engine by hand by means of the bolt on the crankshaft pulley, using a socket and handle. Each sensor has three wires: orange which should have 8V with the ignition 'on', black/light blue which is the ground wire, and then a signal wire (gray/black for the crank sensor and tan/yellow for the cam sensor). Measure between the signal wire and the ground wire while you turn the engine by hand. You should observe a pulsing of the voltage between 5v and 0.3v several times per engine rotation. You can access the wires at the sensors themselves more easily by using straight pins to probe through the insulation of the wires. If you don't see the pulsing and the 8v is present then that sensor is either bad or not mounted properly. But when you say that you don't get any codes does that mean that the check engine light isn't flashing at all or that you do get a 55 code? If you don't get flashing then there may be an issue with the pcm itself or its power supply.
Please read the PS below.
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QUESTION: I get code 12 and 55. i dont get a reading of 12 volts not even for a second i got a 9 , 7 and 10 on the green/orange wire. the crank shaft sensor is new.
ANSWER: Hi Rebecca,
It may be that the automatic shutdown relay's internal points are corroded such that it won't put a solid 12v on the dark green/orange wire. Remove that relay and measure the voltage on the front-most pin (B) which should be a solid 12V because it comes from the battery. The output of the relay goes to pin D at the rear and that is what the dark green/orange wire gets from the relay. It should be a steady 12v while you are cranking it over. If not, then the relay is bad (if the voltage fluctuates) or one of the sensors is not working if you get no voltage (which I described as to how to find out which). The ASD relay is in the rear/inboard corner of the power box. You can switch it with the adjacent compressor clutch relay if it appears to be bad.
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QUESTION: hello Roland, did voltage checks as you discribed to the three wires (crank/cam sensors)one checked for 8v at orange wire both sensors NO voltage with ignition switch on also while cranking eng No voltage. note? do have voltage readings from black (ground) and tan/yellow wire Cam shaft and black(ground) and black/blue crank shaft. Thank you for your quick response. Note checked voltage at auto shut down relay = 12v front pin B also switched out relay with like relay that is know to be working. Note with relay inserted check voltage at rear pin ignition on and cranked get a 1 sec. voltage reading at 12v then zeros out.
I am not clear when you said "...NO voltage with ignition switch on also while cranking engine over NO voltage. note? do have voltage readings from black (ground) and tan/yellow wire Cam shaft and black (ground) and black/blue crank shaft.
What two wires were you measuring across while cranking?
Ideally it would be between each sensor's signal wire and common ground wire (black/light blue), AND you would not be 'cranking' with the starter motor but rather rotating the engine by hand as I described. A digital voltmeter will not sense the voltage fluctuations when the engine is being turned over so fast as it does via the starter motor. So if you didn't turn the engine by hand, then do that know, measuring each sensor separately. You should see 5v and 0.3v back and forth as you turn the engine BY HAND if the sensor you are testing is good. Otherwise, it either is no good or improperly mounted in its hole. Tell me the result for each sensor separately.
It is good to know that there is 12v at the relay and thus there should be 12v on the dark green/orange wire when cranking the engine IF both sensors are working.
So I will await your results.
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