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Discussion Starter #1
Hi all,
This is a long post, but I'm just trying to be thorough. I'm Having an issue with my 96 Impala. I rarely drive my Impala. Put about 15 miles on it in 2012. Well, about a month ago, I drove it to a local cruise in that was about 10 miles away. The car ran great all the way there. After arriving and parking for 2 hours, I got back in to restart and head home. The engine would crank and crank, but would not fire up. After letting it sit for another 1/2 hour, the engine started and I drove it back to my garage as fast as I legally could. During the trip home, the engine spitted and sputtered. Finally got it there and checked the engine codes with my inexpensive code reader. Codes 372 and 1371 were shown.

I cleared the codes and the engine seemed fine for about another 3 weeks. During that three weeks I have started it twice a day and pulled it in and out of my shop for advertisement in front of my custom shop. Last week, while I had the engine idling, it suddenly cut off by itself. I checked the codes and saw the 372 and 1371 again. Afterwards it was very hard to start. A lot of contyinuous craniing.

I looked up the codes and saw that the code PO372 represents: Timing Reference High Resolution Signal 'A' Too Few Pulses
Code P1371 represents: Missing Low Resolution Signal

I assumed that it was time for a new ignition setup so I purchased and installed a new ICM, Ignition coil, and Optispark. All components wee purchased from Carquest and each have a limited lifetime warranty. I finished up the install today and the car fired right up, I took a breath of relief and thought I was in the clear. Well, apparently, I'm not in the clear just yet.

I washed the engine compartment (frame rails and a quick rinse on the top of engine) to get rid of all the spilled coolant from doing the Opti replacement. I was very careful not to get water anywhere near the ignition components. After I washed it, the engine still fired right up and ran great. I cut the engine off to dry up the remaining water off the engine area. I went to restart and It fired right up, but after about 5 seconds, the engine died again and will not fire up now. It continuallky cranks, but no fire whatsoever.

I put a new crankshaft posistion sensor in today with absolutely no change.

I also cleaned the slightest bit of corrosion off of the Opti harness end that plugs into the OptiSpark.

I have tried to get readings from the opti harness and ICM harness as suggested in other posts. I have starred the readings that look out-of-wack.

ICM Harness with key on:
Terminal A: 11.7 volts
*Terminal B: Hardly any AC current
*Teriminal C: 132 ohms, ground continuity with key off
Terminal D: 11.5 volts

Opti Harness with Key On:
Terminal A: 5 volts
Terminal B: 5 volts
Terminal C: 11.7 volts
*Terminal D: 127 ohms, key off 1.5 ohms
 

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I would try a new opti wire harness first. Your test of icm terminal B shows AC signal is not getting through.

If opti wire harness doesn't cure the problem, then the cheap opti you bought might have failed already. Did you loctite the rotor screws when you installed it.

Anyway, Chinese optis have a tremendous failure rate, right out of box, or a few miles down the road. They also fail within a few thousand miles very often, once you finally get a good one out of the box.

Crank position sensor has nothing to do with how engine runs. It's simply there to detect mis fires.
 

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Discussion Starter #3
I didn't loctite the rotor button since I did not disassemble the new Opti. I'm going to return the crank sensor right away. I should have the new harness in a few days. I'll be sure to post results. Thanks for the tips.
 

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not sure if it helps but I had the same codes. high and low resolution pulse circuit. changed the opti. fixed.
 

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if you shop around you can find delphi optis for around 300 dollars. I saw one on amazon that sold for 285
 

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Discussion Starter #6
Problem solved!!!! I put in a new Opti and was very carefull not to get coolant everywhere like last time. This way I woulndt need to wash the engine again (just in case thats what faulted my last Opti from Carquest). My new Opti harness came in this morning so I'll throw that that on in a bit.

Anyway, I just want to say thank you for all of the help in fixing my no start issue.
 
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