Crank position sensor

Tiny
FLAMENBIRD87
  • MEMBER
  • 1995 PONTIAC FIREBIRD
  • 2WD
  • AUTOMATIC
  • 160,000 MILES
I have a 1995 firbird v6 3.4 is there a way to check the crank positioning sensor I have no spark I had my ign mod check as well as all my fueses and coils? I have a crank sensor that is x3 and another that is x24 also a cam sensor
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Thursday, March 31st, 2011 AT 3:12 PM

33 Replies

Tiny
JDL
  • EXPERT
Did you check voltage and ground for the ignition module? Pink wire is voltage, key on. Black wire is ground.

Do you have an injector pulse, engine cranking? Use a noid lite. The two wire crank sensor puts out an ac signal. The three wire crank sensor, puts out a dc pulse.
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Thursday, March 31st, 2011 AT 4:26 PM
Tiny
FLAMENBIRD87
  • MEMBER
Yes when I have key on there is 10v on the pink wire and ground blk is good.I will check the two and three wires while cranking and you mean put a noid at end of the wire that goes to injector?
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Thursday, March 31st, 2011 AT 11:15 PM
Tiny
JDL
  • EXPERT
Yes the noid lite plugs into injector plug, check for a flash, engine cranking.

If I had to suspect a crank sensor, the one with two wire connector.
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Thursday, March 31st, 2011 AT 11:46 PM
Tiny
JDL
  • EXPERT
I was wrong about the crank sensor, suspect the three wire crank sensor? It should start and run with only the 24x signal.
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Thursday, March 31st, 2011 AT 11:55 PM
Tiny
FLAMENBIRD87
  • MEMBER
Ok I checked V with the coils off the module and all wires pluged in and key on, there is battery V (12.45v) at the spade connectors that the primary coils slip over. Now there is a two wire connect ppl and ylw do I check the v's pulse on those while eng cranks? Ac V's? What should it read?And the three wire dc v's are what color?
Thanks
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Thursday, March 31st, 2011 AT 11:57 PM
Tiny
FLAMENBIRD87
  • MEMBER
Ok so just check the three wire what color are they and is one ground? The larger connector has r/blk, blu/blk, wht, wht and tan the one wht is for tack right
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Friday, April 1st, 2011 AT 12:12 AM
Tiny
JDL
  • EXPERT
The crank sensor with two wire connector goes to ignition module. Purple wire and yellow wire. You can do an ohms test, connector loose, everything turned off. Use digital multimeter. 2K ohms setting. 800-- 1200 ohms. If it shows open circuit, no reading, either the wiring circuit--wiring connector or sensor is faulty.

Connector loose, engine cranking, .8--1.4 ac volts.
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Friday, April 1st, 2011 AT 12:22 AM
Tiny
JDL
  • EXPERT
For 24x signal, 3 wire connector. Terminal A is voltage. Terminal c is ground. Terminal B is signal, on and off voltage pulse.
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Friday, April 1st, 2011 AT 12:30 AM
Tiny
FLAMENBIRD87
  • MEMBER
Ok I just checked the ppl and ylw wire connect with it off the ign mod between the two wires shows nothing OL on my meter. Does it have to be at a certain position on on crank to have reading? Or does that mean it is open?
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Friday, April 1st, 2011 AT 12:48 AM
Tiny
FLAMENBIRD87
  • MEMBER
Your diagram is different than mine. The wire colors are different here is what I have on my car I checked these they are the color of my wires exact
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Friday, April 1st, 2011 AT 3:03 AM
Tiny
JDL
  • EXPERT
Were you using a digital multimeter? Were you doing an ohms test or voltage test? If you were doing a voltage test with digital multimeter, you should have got some kind of reading, engine cranking.

Nice diagram, flamenbird87, mine came from our database, the databases are not always correct.
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Friday, April 1st, 2011 AT 2:45 PM
Tiny
FLAMENBIRD87
  • MEMBER
This digram came out of my Chilton but is not actually 95 it covers 82 to 94, anyways I used an ohm meter it is digital and automatic no scale. It read OL not 00.00 between the ppl and yel wires on sensor with it disconnected from mod. It should have continuity (res) right?In the Chilton it shows the sensor located on block behind starter. Would this sensor or wire being bad keep it from starting?
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Friday, April 1st, 2011 AT 4:38 PM
Tiny
FLAMENBIRD87
  • MEMBER
I just checked sensor in question with the eng cranking on the ac v's setting it is fluctuating between.348 and.535 does that mean it is good? (Note my mod and coils are disconected from wire harness) and why does it not ohm out between the ppl and yel?
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Saturday, April 2nd, 2011 AT 1:29 AM
Tiny
JDL
  • EXPERT
That ohms spec came from our database. I'd replace it. Did you ohm the senor itself? With that type sensor, the higher the rpms, the higher the output. In the past, I have taken that type sensor out, laid it on the work bench, hooked up the dmm to sensor terminals, waved a wrench in front of magnetic end and I got a reading, don't remember the actual reading. That sensor was intermittently faulty, I replaced it. Our info says the vehicle will run with only the 24x signal, but, I don't know if it will start without the 3x signal?
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Saturday, April 2nd, 2011 AT 3:58 PM
Tiny
FLAMENBIRD87
  • MEMBER
Ok I visually checked sensor no broken wires.I bought another digital meter and tried ohming on all settings from 20 up to 2000K no ohms, (open) then I tried checking for ac volts while cranking eng, this time 0n the 200 scale I got a steady.1 only, also tried 600 setting on ac volt scale nothing o. Oo incidentlly why do you use an ac volt scale and not dc? Just curious.
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Saturday, April 2nd, 2011 AT 7:54 PM
Tiny
JDL
  • EXPERT
It depends on the crank sensor, the two wire sensor puts out an ac signal, that signal goes to the ignition module, the ignition module converts that signal to dc, the computer can't handle ac. You can get a signal with dmm set on dc, even though it puts out ac signal. I've seen it. Maybe it is reading dc one way and then dc the other, I don't know?

The hall switch crank sensor, three wires, is a dc signal, on the signal wire.
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Saturday, April 2nd, 2011 AT 8:23 PM
Tiny
FLAMENBIRD87
  • MEMBER
Ok undestand Thanks, so if the coils and the mod is ok and this sensor is only putting out.1 and not ohming out then this 2 wire crank sensor must be bad correct? I'll pull it if so.
Thanks i'll let you know what happens after I replace it.
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Saturday, April 2nd, 2011 AT 8:49 PM
Tiny
JDL
  • EXPERT
Yeah, let us know what you find.
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Saturday, April 2nd, 2011 AT 9:16 PM
Tiny
FLAMENBIRD87
  • MEMBER
Ok I took the sensor off and noticed that the end that has the pickup on it was alittle corroded and had light surface rust. This car had a blown head gasket when I bought it had water in the oil.I fixed it and drove it till this prob happened. So I took a brass brush and cleaned it. Do you think it was just not getting a good signal from the crank? I also checked wires by loopn it with a paper clip then ohmed it, it is fine.
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Saturday, April 2nd, 2011 AT 11:06 PM
Tiny
FLAMENBIRD87
  • MEMBER
Ok just put it all back together and then check sexor while cranking and it is showing on a 200 acv's scale.1 to.5 fluctuating. But still no spark is that volt reading good on the sensor? Or? I see you wher say on one post.8-1.4 ac volts
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Sunday, April 3rd, 2011 AT 2:26 AM

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