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Crank Sensor Wiring Issues

Crank Sensor Wiring Issues

Postby fish2222 [OP] » Dec 23 2011, 11:15pm

Hi guys, I am new here, but I need to ask a question. I have a 96 Silverado C2500 with the 5.7L engine. Anyway, I went out one day to start it, and it just cranked over and never started. I figured it was low on gas (I hadn't drove it for a few weeks and it was low then) so I put a couple of gallons in it. Still did not start. I pulled the cap and rotor to make sure they were alright, a little corroded, but looked alright after I cleaned it up. I then put a timing light on it to see if there was spark while it was cranking, of course, nothing. I checked fuel pressure, 60 PSI, should be good. Tested the coil, primary and secondary both good. So I got to thinking, and thought about the crank sensor. I looked at a deal on testing it, crawled under the truck, and found that the wires had been completely pulled out of the plug! Not sure if it was a cat, rat, or sabotage. Anyway, I found a wiring diagram (since they were pulled out I had no idea which one was which) and reconnected all the wires. 12v to pin A (pink), ground to B (purple), and pickup to C (yellow). Guess what? Still will not start. Now my question is this. Since the ground for the sensor is provided by the computer, is it possible that since the wires were pulled loose, maybe power hit the ground during one of the key cycles while I was cranking on it and fried the computer before I knew it was pulled loose? Another thing is this... I have an OTC scanner that I tried to plug in and get codes from and check the running diagnostics. It keeps telling me that the ALDL connection has not power and I need to turn the key on even though it is on. Any thoughts? Thanks for any help!
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fish2222
Firing on 1 cylinder [L1]
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Re: Crank Sensor Wiring Issues

Postby ASTE25 » Dec 23 2011, 11:33pm

It does sound like you may have a computer problem. I would make sure that you do not have any blown fuses first.
Jordan
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Re: Crank Sensor Wiring Issues

Postby fish2222 [OP] » Dec 23 2011, 11:45pm

I checked the fuses in the fuse panel on the side of the dash and under the hood in the relay center box, but they all look good. I am debating whether to try to find another computer or not. One thing I am wondering about, and maybe this would explain it, is that the crank sensor does not test out right doing the test I read about. It says you can turn the crank clock-wise by hand and the sensor output should go from 0 to 5v when it senses the magnet with the ignition on. I had a constant 2.2 mv the entire time while turning it over.
Original Poster
fish2222
Firing on 1 cylinder [L1]
Firing on 1 cylinder [L1]
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Re: Crank Sensor Wiring Issues

Postby ASTE25 » Dec 23 2011, 11:52pm

Change the crankshaft position sensor first, it may have been damaged when the wires got jerked out. If it is not reading what it is supposed to read, you know it's bad anyhow.
Jordan
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Re: Crank Sensor Wiring Issues

Postby fish2222 [OP] » Dec 24 2011, 12:13am

One more question to go along with this... I have a 16244210 ECM in the truck. If I find another 16244210 ECM to try, will it work even if it is out of a blazer or something else? Does this have a removable PROM that can be moved from one to another? I haven't messed with too many this new, just late 80's and early 90's tuned port stuff with removable PROM's.
Original Poster
fish2222
Firing on 1 cylinder [L1]
Firing on 1 cylinder [L1]
Posts: 12
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Joined: Dec 23 2011, 11:03pm
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Re: Crank Sensor Wiring Issues

Postby ASTE25 » Dec 24 2011, 12:39am

I'm not sure about that question. I'd try the sensor first.
Jordan
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Re: Crank Sensor Wiring Issues

Postby BuxCamper » Dec 24 2011, 12:48am

If the wires were ripped from the sensor there's a good chance an internal connection in it is now open. 2.2mV sounds like background noise being picked up on an open circuit.
-- Mark

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Re: Crank Sensor Wiring Issues

Postby fish2222 [OP] » Dec 24 2011, 2:04am

I guess I need to verify I have the correct wires to the right pins on the crank sensor. I found another write up that says that power should go to pin C, not pin A like I have it. Anyone know what pin should be what?
Original Poster
fish2222
Firing on 1 cylinder [L1]
Firing on 1 cylinder [L1]
Posts: 12
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Joined: Dec 23 2011, 11:03pm
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Re: Crank Sensor Wiring Issues

Postby ASTE25 » Dec 24 2011, 2:07am

Check one of the parts websites, like Autozone. They sometimes have good info like that on them.
Jordan
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Re: Crank Sensor Wiring Issues

Postby fish2222 [OP] » Dec 24 2011, 4:03am

I found a few places that have wiring diagrams, but autozones is terrible. It shows wiring colors, but not the pinouts of the plugs.
Original Poster
fish2222
Firing on 1 cylinder [L1]
Firing on 1 cylinder [L1]
Posts: 12
Topics: 1
Images: 3
Joined: Dec 23 2011, 11:03pm
Years of membership: 2 years of membership2 years of membership
Year: 1996
Make/Model: Chevrolet Silverado
Extra Info: HD 2500
Group Membership:
Registered users
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