QuestionI want to thank you all for your help in solving the problem I had with no spark. Everything that you had me check lead me to the problem. I'm not sure how this happened but the wire going to the map sensor has the same three wires and plug end that the crank and cam sensor's have. For some unseen reason the proper wire that goes to the crank sensor was plugged into the map sensor. There was never a need to unplug this wire so as far as I can remember it was never unplgged. But thanks to you all I couldn't have found the problem. I call this lesson's learned by an old back yard mechamic.
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I did all the checks up to the coil pack and here are the results. When I check the signal wires I do not have 5V from the sensors when I hooked them up they read 0V. When I turned the motor over by hand I can hear the fuel pump kicking on and off when checking both sensors. (IS THAT CORRECT).I checked continuity on both plugs and everything checked fine there. Then I checked the 8V on both plugs. The cam sensors checks OK, but when I checked the crank sensor it showed nothing pluged in, and when the connector is unplugged it shows 4.28V. From that indication I am asumming that I might have a short somewhere or a bad componet associated to that 8V line. I stopped there for now until these item's can be fixed. Can you please advise on the next steps to check.
Thnaks Tim
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I am working on a 1997 Chrysler Concord and am getting no spark.I just replaced the Trans when this all started. I back tracked all my steps, all connection are made without fault. The car does crank over with no problems, I rechecked the ring around the torque converter to make sure I didn't damage it. It was OK. I was able to download information from ALL DATA concerning the sensors. I have a 5V reading and a good ground on both sensors. The signal wires I'm not sure about I can't find any information of what voltage or type of signal it is, so it can be checked. I tried using my meter, but when I crank the car over the meter pegs out to a one. My old PCM had two codes off of it #11 which is a no signal from sensor's and #31 Purge canister disconnected, which is because it was taken out to axcess the PCM. I replaced the PCM with a used one and now all I have is the #31 code left and still no spark. Everything is still pointing to the PCM as far as I can see. I asked the local Dodge garage to see if they can check the PCM they couldn't do it out of the car (THEY SAY). This job was suppose to be a charity job for a women at my church and it seems all I'm doing is sinking money into it which she don't have. What a big CF. Please let me know what you think.
Thanks Tim
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Hi Tim,
I would probe the crank and cam sensor signal wires with a voltmeter while you turn the engine by hand using a socket and ratchet on the crankshaft pulley. With the ignition key in the run position: Measure the voltage on the signal wires (crank=light blue/dark blue, cam=tan/yellow) as compared to the ground (black/light blue) wires at those sensor plugs. It should change from 5V to close to 0V several times for each full turn of the crankshaft. By the way the voltage on the orange wire at both sensors should be 8V. If that is happening and the signal wires are properly attached to the PCM (the 60 pin connector then to pins 24 and 44, respectively). If you check the continuity of those wires and you have the signals, then the PCM should energize the autoshutdown relay when you are cranking the engine to start it and you should see 12V on the dark green/orange wire at the coil pack plug compared to ground. The last voltages to check would be on each of the other three wires to the coil, and those should be checked for voltage pulsing using a neon glow lamp (one lead on the dark green/orange, the other lead on each of the other three pins) as you crank the engine with the starter. Finally check the coil resistances which should be 0.45 to 0.65 between the dark green/orange wire's pin and each of the other three pins, and the resistance betwee each pair of spark towers should be 7,000 to 15,800 ohms.
Good luck and let me know what happens, please.
Roland
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Hi Tim,
The fuel pump clicking is probably a good sign showing that there is a signal(probably crank) getting to the pcm which then turns on the pump for about a second. It would hold it on if the signal were normally fast (i.e, the engine was running on its own rather than being turned by hand). The orange wires at either sensor should both have 8v on them because they come from a common splice that is derived from pin 7 of the PCM. I would just unplug both sensors and then with the ignition on see if you have 8V at both sensors' plugs. If not then the one without the proper voltage may be either open or shorted to ground. You could check that with an ohmmeter. Once you have 8V on both orange wires at their plugs, then plug them in. On the signal reading, what happens is the 8V supply will cause the sensor to alternately put out 5V or 0V depending upon whether the sensor tip is opposite an opening or metal, which of course depends upon the engine being rotated. So what you look for is the signal to jump between 0 and 5V as you rotate the crank. If it does, then the sensor is ok. If not, then either the sensor is not close enough to the metal or it is no good. To re-position the sensors get a stick-on paper spacer at the dealer parts dept, clean the tip of the sensor and put it on the tip of the sensor, then install the sensor with the tip pressed against the surface it "looks at".* You may want to eyeball the hole to make sure there isn't an opening at that point when you install it, if so rotate the crank until there is solid metal to press the tip against. Then press the tip against the metal and tighten the nut that holds it in place. The spacer will "self-destruct" but leaves the proper spacing for the signal to be generated. If you still don't get the 0-5 altering voltage pattern then that sensor is no good. I think there is hope, so hold in there.
Roland
The manual shows the spacer is used for the cam sensor. But it is not mentioned for the crank sensor. You might check with the dealer to verify that it uses a spacer also.
AnswerHi Tim,
Thanks for the update. I looked at the wiring diagrams and interestingly found that the colors on the wires for the MAP are not supposed to be identical to those on the crank except for the ground wire (black/light blue) so maybe someone spliced in a crank plug with its wires to replace a faulty MAP plug? In any case, I am really glad to learn that you have this volunteer project resolved successfully. Power to you!
Roland, a fellow old back yard mechanic (70 y-o in 2 weeks)!
