I will check it when I get home this weekend. It seems to be picky. Sometimes it will start, other times it won't.

 

My Red 93Z-28, Speedy and I have a good natured dis-agreement on weather or not an intermittant DTC 36 will or will not cause a lack of spark in the LT1 engine. If you want further details about this, reference this thread:

https://www.camaroz28.com/forums/sho...d.php?t=737219

If you just want to get your car running again ASAP ...... please do as Injuneer suggested, double check the "signal path" from your Opti to your PCM, and ...... if all tests good there ....... replace your Opti.

 

Two years later...

I performed the Opti and Spark test from shoebox's site and here is what I found, my values are in red:
ICM Connector
Terminal A 10 Vdc or more 11.7 Vdc
Terminal B 1-4 Vac while cranking 0 Vac
Terminal C continuity to ground Forgot to check...whoops
Terminal D 10 Vdc or more 11.7 Vdc

Optispark Harness
Terminal A ~5 Vdc 4.76 Vdc
Terminal B ~5 Vdc 4.76 Vdc
Terminal C ~12 Vdc 11.57 Vdc
Terminal D ~0-0.2 ohms ground 16-17 ohms, checked continuity from opti harnes to ECM harness, and ECM harness to ECM and checked out 0 ohms

Coil Test - Crane Coil
2.37k-ohms at all 4 terminals

This tells me my opti has failed, but I don't understand the 16-17 ohms of resistance on terminal D, yet continuity checked out...although I did not check from opti harness to ECM, I disconnected the harness to check.

I took the opti cap off and cleaned it prior to these tests, the opti harness connector is clean. This sucks because it only has less than 10k miles on it and opti prices have almost doubled since I last bought one. I know the typical answer is no, but since it is just the optical side that failed, would it be worth it to just get the optical side and use my cap and rotor? I put a paperclip across A-B in the diagnostic terminals and the only code it gave me was 12, which is normal to let you know the system is working, but the engine won't fire because of the issues listed above

 

My Red 93-Z28, I have replaced three (3) Opti's on my car and, like you are now experiencing, ALL of my Opti failures were due to just the optical sensor failing in these units. The caps and rotors on all my bad Opti's always looked clean, bright and were showing little, (if any), real wear.

Like you are now thinking, I to would have loved to replace just the optical sensors in these failed Opti's, but, despite all my searching ........ I could NOT find any source for JUST the optical sensors!

Times may have changed, sooooooo ....... if you do find a source selling just the optical sensors for these units ........ I would sure like to know about it.

Again, like I said several years ago now, (and your recent testing has shown), if you want to get this car up and running again ......... just replace the Opti!

 

I believe you can get the optical side at any parts store

 

If you can ..... then indeed the times HAVE changed!

Believe me a few years back ....... you had to buy the WHOLE opti to get the optical sensor. They always sold the cap and rotor separate, but if you needed the optical sensor portion...... you bought an entire new Opti.

If you do wind up buying JUST the optical sensor for your Opti ........ can you post up the part cost, part manufacturer and part number for it. I'm sure that there are a LOT of us LT1 owners on here who would really appreciate that info.

 

I'll check on those prices for you Monday, 97 Speed Z

Update, drove an hour away last night to get a reman opti because I'm in a time crunch and it fired right up. A HUGE THANK YOU to Shoebox, you rock

 

First off, congrats on getting your car up and running again, that's the important thing.

But, "inquiring minds" do want to know ............. did you ever find a parts store/source that does sell JUST the optical sensor module for our Optisparks????

 

He indicated you can get the "optical side" at any parts store. I interpret that as the "back 1/2 of the Opti" and not the optical module. Hopefully he will clarify and not leave us hanging.

 

Fred, your are correct, I interpreted his response to mean the optical sensor module, probably because ....... that is what has always failed in my personal Opti replacement experiences.

Truthfully though, even being able to buy JUST the entire "back 1/2" of the unit, would still be a departure from what I was finding just a couple of years ago. Like I said in one of my earlier posts to this thread, you could ALWAYS buy JUST a new cap and rotor, but, back then you could NOT buy even just the "back 1/2" of the Opti itself. If the optical sensor module failed ....... your ONLY recourse was to buy a WHOLE re-manufactured/new new Opti.

On another note, has having yet another failed Opti "field case" showing ONLY a DTC 36, and preventing engine operation, convinced you that GM is wrong on this???

 

Hi Fred, yes that is what I meant, the back half of the opti, I'll try and update this tonight, when I'm not on my phone, with actual prices. Thanks for your help with the issue

 

I think whether the engine will run depends on the failure mode. Total loss of signal = still runs. Erratic signal may not run.

 

Unless the total loss of signal is while cranking, then it won't fire the injectors or fire the coil

 

For all Y'all that keep complaining about the loss of the hi res signal, allow me to clear up one thing.

In no way shape or form will the loss of the hi-res signal stop the engine or prevent it from running. PERIOD. Even if it's intermittent.

2 months before I sold my 94, I cut the wire for the hi-res signal. I left it cut and started and drove the car.

Then I twisted the wires back together and did not put tape on them. I drove that way for 2 months.

To be sure there were no other DTC's, I left my Solus connected the entire time. I would confirm the code and reset it.

Here's the kick in the teeth. The code would come back any where from days to seconds after resetting it.

Guess what, it still ran with NO noticeable difference.

Case closed.

Oh and I showed the cut wire to the guy that bought it. Guess what, he didn't have a problem with it.



Now move on to something else.

 

I don't want to "beat a dead horse" here, but ...... does anyone subscribing to this thread know for sure if we can now buy JUST either the "back half" of an Opti or ..... the optical module sensor itself?