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Discussion Starter #1
I have a new problem. It started with code 35, 36. Scantool shows crank sensor status: OFF Crank reference pulses 0.0


I replaced the CPS yesterday with no change.


anyone had to rewire this sensor?
 

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It might be a stupid question, but is the thing that triggers the CPS still good. At my old job, My mechanics would routinly replace prox switches and then claim that the new one was bad out of the box, because it still didnt work. It would usually be that the target was damaged, missing or out of adjustment.


Tim
 

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Not a bad question. The fuse is good, but no volt signal at terminal C of the CPS connector. I'm not sure where this volt signal originates (ECM, fuseblock) any suggestions appreciated.


I see in my chilton wiring diagram that MAP 5v, baro 5v, and crank sensor are on the same circuit (c10). Since I have normal MAP and baro readings I will splice a new wire from the c10 curcuit to the CSP connector c terminal.


Edited by: quantum mechanic
 

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Hmm, knowing that it is getting power, I would cheat it with a hunk of ferrous metal (a screwdriver would work) with the engine off, and see if you get any voltage out of it.


If memory serves, the trigger is a 4 position "star" wheel. I cant see all 4 'teeth' breaking off at once, so I would have to guess that you have too much of a gap between the sensor and the target.


Good Luck!


Tim
 

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Discussion Starter #5
Would I have to remove the timing chain cover to expose the trigger? I assume yes because I had the pully and harmonic off yesterday while installing the crank sensor (I wanted a good look) and didn't see anything beyond the crank end.


I found that the curcuit is good at the c terminal of the CPS connector and reads nearly 5v on the multimeter. so, no splice.


The how much adjustment is there in the trigger? Does it mount on the crank or next to it? How hard to replace it?


Also, I noticed the Cam pulses at 0 ( scantool). Is this the same sensor or does the optical sensor read this.Edited by: quantum mechanic
 

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PCM compares 3 optical signals in inj pump to Crank Pos Sensor for inj timing.


I'd suspect connector problems before changing sensors. Voltage should be about 5.12v to ground.


The engine harness connects to the inj pump sensors thru multiple connectors around the pump.


The engine harness connects to the PCM harness just behind the fuel filter - multiple connectors there.


Make sure the pins and sockets are clear - tinned copper can soon oxidize over periods of damp-dry cycles.


If white, powdery - time for some CLR, rinse with baking soda, rinse with clear water, blow dry, then GM electrical contact insulation grease. Used in Corvette PCM systems.


Since you're seeing zero from several sensors, suspect PCM to engine grounding, including the one in the extended FSD harness.
 

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Discussion Starter #7
I had white powdery corrosion on the CPS connector. I'll look for bad grounds/connections. Edited by: quantum mechanic
 
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