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Crank sensor ? 94 caravan 3.3

Discussion in 'Projects, mods, restoration' started by Ianmalcolm, Oct 5, 2015.

  1. Ianmalcolm

    Ianmalcolm New Member

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    New alternator, drive 600 miles Ok, then will not start. check codes get 11, change crank sensor still get 11. Checked wires, fuel pump, coil, good battery etc, still no start. Ideas much welcome......Ian.
     
  2. KOG

    KOG KOG
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    Crank and cam sensors use the same power. If cam sensor shorts it will set a crank sensor code. Don't even ask me how I know---
     
  3. ImperialCrown

    Level III Supporter

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    Welcome to Allpar. Has it got spark and fuel? The fuel pump can be working, but if the fuel injectors stay closed, you still don't have fuel.
    Does a shot of carb cleaner in the throttle body fire it up momentarily? With a helper cranking the starter, do you have a nice blue-white spark to ground? A noid light for spark test is a safer test method.
    Do you have 8 volts at the Orange wire at the cam and crank sensors with the ign on?
    Is the Bk/LB sensor wire a good ground?
    Always diagnose first.
    http://www.allpar.com/fix/codes/index.html
     
  4. Ianmalcolm

    Ianmalcolm New Member

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    I do have fuel pressure at the rail test point, and 9dcv at the orange wire. Ground wires look good so thought my try another crank sensor.
    As far as I can see the computer triggers the auto shutdown relay if no pulse from crank, and are the spacers on the end of the sensors necessary for good operation ? I will go back and check all of the things you all have said thou, thanks. No spark at all at end of plug wire also with another coil pack.
     
  5. ImperialCrown

    Level III Supporter

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    If you have already changed the crank sensor, make sure that the replacement part is OEM (it doesn't have to be Mopar).
    Code 11 doesn't necessarily have to mean a crank sensor fault. Check all wires to and from the PCM and sensor.
     
  6. Ianmalcolm

    Ianmalcolm New Member

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    Have just checked wiring from PCM to both crank and cam sensors. All good and with ign on get 9v on Orange wires
    and 5v at yellow ones. Thinking maybe should change cam sensor ?
     
  7. ImperialCrown

    Level III Supporter

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    The crank sensor is the one responsible for spark. The cam sensor just times the injector firing pulses. A vehicle can even start with the cam sensor unplugged, but it may crank awhile until it figures out the engine timing positions through the crank sensor.
    The ASD relay will stay closed as long as the starter is cranking. If the PCM does not see the crank sensor after a few seconds, it will open the ASD relay.
    I would continue diagnostics.
     
  8. Ianmalcolm

    Ianmalcolm New Member

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    Ok, installed new cam sensor to go along with the crank sensor, double checked all wires from sensor connectors to PCM and did the wiggle thing also and still get good continuity, and 8.7v on Orange wires. Still get code 11 !!! What other thing should I check before a computer swoop ? Also with just 5 or 6 seconds of cranking I get 40lbs at fuel rail but no oil pressure reading at dash. Thanks for your help so far.
     
  9. ImperialCrown

    Level III Supporter

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    You may not see oil pressure until it starts. If you can confirm that the sensors and wiring are OK, then the PCM is about the last suspect left. It would be nice to confirm that the cam/crank signals are actually at the PCM terminals and in 'sync' before condemning the PCM.
    An advanced scan tool like the Snap-On MT3500, SPX/OTC Genisys or Chrysler DRB III would be able to confirm (or not), the presence of the cam/crank sensor signals.
     
  10. Ianmalcolm

    Ianmalcolm New Member

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    Is there any way that I can check for pulse at the crank PCM terminals with a multimeter, as a scan tool is very expensive ? Is the crank pulse a voltage ?
     
  11. ImperialCrown

    Level III Supporter

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    It is a voltage pulse, but happens too quickly to watch on a meter, you might only get the 'average' of the voltages.
    A good scan tool can tell you if the cam and crank signal is 'lost' or 'present' and if they are in 'sync'. It would help diagnose a possible failed PCM.
    I'm not suggesting that you buy an OBD 1 scan tool for this repair, it would probably not pay for itself.
    A dual-trace scope can watch the cam and crank at the same time. With one waveform over the other, you can also observe the relationship between them.
     
  12. Ianmalcolm

    Ianmalcolm New Member

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    Thanks for your input Imperial, there is no connector for my OBD1 scanner on the 94van so that is out. So I think my next step is to find a good computer to swap and hope that does it. Regards.......Evol.
     
  13. ka9yhd

    ka9yhd Active Member

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    The connector is located under the hood and it is a L shaped 6 pin connector, but only using 4 wires, which is on the wiring harness that goes to the ECU next to the battery. In the picture I have the OBD1 connector removed from its holder or cover. The connector is sitting on top of the holder or cover.
    [​IMG]
     
  14. valiant67

    valiant67 Rich Corinthian Leather
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    Just to expand on the post above: There are two OBD connectors on your van. The one above is the connection for the engine computer. The other connector is under the dash for Transmission, ABS, air bag, body computers. Therfore there are two different OBDI cables needed to connect a scanner to an OBDI Chrysler vehicle.
     
  15. Ianmalcolm

    Ianmalcolm New Member

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    Well thanks guy's, you have just made me realize that the scope that my brother sent me is a OBD 2. No wonder I could not find the connectors !!!!! I think that I will put this project to one side for now until I get a used computer at a good price. Thanks again for all the input......regards.....Ian.
     
  16. Ianmalcolm

    Ianmalcolm New Member

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    Just a thought on my crank sensor problem. While turning the engine over with the battery should I see some movement of the rev counter ?
    Even though I still get the no crank code !
     
  17. Ianmalcolm

    Ianmalcolm New Member

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    Update on my code 11 problem. Have solved the problem with a guy who has the gear to check for more than I can, turns out the Cam sensor was not all the way inserted into its hole. It was in place so as the screw went in Ok but not good enough to give a pulse to the computer. But to thro a code 11 ? The Van runs well now !
     
  18. ImperialCrown

    Level III Supporter

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    The crank sensor is necessary for spark. The tachometer gets its signal from the crank sensor.
    The cam sensor basically times the fuel injector pulses. It tells the PCM where #1 cylinder TDC is. Both signals are important and their relationship is interrelated.
    Was the insufficient cam sensor signal seen on a scan tool?
     
  19. Ianmalcolm

    Ianmalcolm New Member

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    Yes Imp it was a poor cam sensor signal, and hooking up with a gentleman with an OBD 1 reader did the trick. And after fixing the fuel rail with some plumbing fittings and some solder, she runs like a sewing machine !
     
  20. 85lebaront2

    Level 2 Supporter

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    Wrong answer, I had a couple of 3.3L vans, One I owned and one a friend owned. Neither would run with the cam sensor disconnected. Another item, a bad timing chain throwing the cam and crank sensors out of sync can cause a no start condition.
     

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