optispark code #36

I'm having some real trouble identifying the cause of an ECM code #36 (low/high resolution pulse signal) after a distributor replacement.

This car has over 160K miles on it and I changed the distributor with an e-Bay offering and made the necessary mods to vent it as detailed in several magazine articles. The original distributor was in very bad shape. The rotor had gotten hot enough to melt the material around the screws and it was not possible to turn the distributor by hand without extreme force.

Once changed it registered a code 36 shortly after start up. It also took several revolutions to fire due to the absence of the low resolution pules. No other faults were registered and no other problems were indicated or apparent.

Thinking that I had obtained a cheap copy off e-bay I ordered a new replacement from JEGS. The new distributor is also hard to start, throws the exact same code, and now the cooling fans run all of the time as well.

Researching the internet led me to the purchase of a new optispark wiring harness and a physical inspection of the firewall harness. Replacing the optispark harness didn't make any difference and I could not find any burned, grounded, or otherwise suspect wiring(even behind the intake).

I have the service manuals and reviewed the wiring diagrams in detail but have not been able to locate any junction where these two circuits run parallel, and the test voltages at the connector show check OK.

It does not seem to affect overall operation as the car is still driveable but it's a nuisance that I would like to remedy. Surely there is some need for the low resolution pulse or it would be there.

I'm leaning now towards a bad ECM given the state of the original distributor when it was removed. Maybe it caused excessive current loads within the ECM?

Has anyone out there had a similar experience with the early optispark?  

I have a 1994 Firebird with exactly the same symptoms.  I am on my third optispark, like you all of my voltage checks seem to be ok. I too suspect my PCM.  Did you ever get yours going?  

change the pig tail that connects the optispark distributer to the wiring harness...  it is available through several sources..

delco shows it as a part number PT2386    the wires do fatigue...  the terminals inside the connector.. go bad...

professional mechanics can disconnect the ecm... carefully backprobe the ecm connector.. crank the motor and  with a digital storage scope.. cheep ones start at $4K  and charge you a few hours labor...  look at the output signals from the sensor... or lack of them...

or you can take a short cut... since both of you have been in and replaced the optispark unit..   replace the connector.. with shrink tubing and crimp terminals.. one might also want to invest in a proper crimp tool.. like a chanellock 909 or 909cb...  under 20 bucks... sears has  some in the sears companion brand for under 10 bucks... if 20 is too much..

one wire at a time...    please...  and offset the cuts in the wire.. so you don't end up with all four at the same point...


i cannot count how many electrical pig tails i have changed on cars to fix problems..