Background: I started experiencing a bad miss in my '85 and it gradually ran so badly I barely made it home. Now I have a no start situation and have no spark at the plugs whatsoever.

Reading my FSM and going thru each distributor component I am trying to test the leads from the pick up coil. When I check the pin I think is the right one and connect to ground I get no reading at all. FSM says it should have an "infinite" reading. When I check resistance to both pins I get 800 ohms which is in spec.

Would the no reading indicate a bad pick up coil or am I doing something wrong? I am not sure how my multitester actually indicates "infinite".

 

"INFINITE" basically means an OPEN circuit. So if you are reading a value...then it is NOT INFINITE.

I do not have my manual in front of me...but go off of what GM says. Also...the pick-up coils wires can move..so when you have them connected,,,you might want to slightly move them and see what happens. I have had many cars where the wires in the insulation were broken and showed up when moved.

Google , 'infinite reading on ohmmeter'...you will see for yourself.

DUB

 

No its not reading anything, it reads zero. I will wiggle the wires around tomorrow.

Will a bad pick up coil have the symptoms described?

 

FSM says it should have an "infinite" reading. When I check resistance to both pins I get 800 ohms which is in spec.

NOW you write:
No its not reading anything, it reads zero.

I do not know what your ohmmeters shows on its digital display...if you have that type.

Do you understand what 'infinite' means????

MY ohmmeter shows a '1'...which means INFINITE...and a '0' when I get a good contact between two components tested....much like if I touched both of my leads together.

I am guessing here...you have to 'completely fill in the spaces'. I AM IN THE DARK!!!! BE very precise and descriptive....even if you have describe how your tool works and how it displays what you are reading.

DUB

 

Many digital meters will show "OL" for open or no connection (what a lot of people call infinite resistance).

 

FSM describes two tests for the pick up coil. The lead from the pick up coil attaches to two of the five pins of the ICM. I disconnect the 2 pin connector and 1st test is from one pin to the base of the dist.. The second is probing one pin to the other. 1st test reads 0.0 (supposed to be infinite)and second reads 800 ohms.(range 500 to 1200 ohms I think)

Truthfully I dont know what my LG multitester indicates as infinite. I will go some looking and see.

 

Hmmm, let me check again. I have some missing segments and what I am thinking is 0.0 may be OL

 

Thank you Cliff, I hafta say I dont know how to read my multimeter. It is indeed displaying OL.

So now according to my FSM, my pick up coil passes, my ignition coil passes. I took my ICM to autoparts and it is good. So now its down to what? Wiring? Ignition switch? ECM?

 

Even worse I guess I dont know how to use the damn thing. Apparently I was not making good contact with the pick up leads so now after rechecking them, I am getting a 24 or so ohm reading which is not a good thing according to the FSM as it should show open circuit and the OL display.

I guess it makes sense as to the failure of the pick up coil, the misfiring starting out small, increasing in intensity to complete failure. The pick up coil is only about $25 so if it isnt that I am not out much money and some time.

 

The FSM saves me again! Spending that $100+ at helminc has paid for itself over and over many times. It was the pick up coil. A PITA to replace it but it was the first time I have ever tried to rework a distributor. This car has presented me with so many firsts. I just wish it would give me a break for a little while!!

 

JUST MAKE SURE...that when you knock the roll pin out of the gear at the bottom of your distributor...that you MAKE SURE that you put it on EXACTLY the same way...and NOT 180 degrees out. BECAUSE the gear ( if put on 180 degrees out) will change the way your pointer on your rotor button sits when you get it to go back in.

Have you ever pulled a distributor before...and put it back in?????

DUB

 

Yes Dub, I have. Just never disassembled one.

FSM procedure was very explicit on keeping up with which way everything came apart and I marked everything to make sure it went back in correctly. Car is running fine in spite of what you may think of my skills.

I appreciate your input Dub. Most of us are not fortunate enough to own a Corvette shop and have the skill set you have. That being said, inexperience with a certain system does not mean it cannot be conquered by most folks here on the forum, even myself. I have been turning wrenches by necessity, not by trade, for about 35 years so its always a learning experience for me. This car has been a classroom project on wheels but I have managed to get thru every issue with my limited skills, the FSM and input from knowledgeable folks on this Forum. Things that are elementary for you are sometimes a mystery for me, thats why I ask.

 

HUH!!! I learned something new.

 

I do not mean to come across that 'your skills' are lacking. BUT...you also have to be aware that there are areas in the FMS that are wrong and misprinted.

ALL I am trying to do is make sure you do not mess up. I also know that many members are inexperienced....which is why I spend time every day after work to offer suggestions, ideas and guidance. AND I rarely tell them that "they can't do it".

I DO NOT want to make you feel that if you 'ask for help'...you are going to get 'beat down'. But if suggestions are given ...for example you understanding your ohmmeter....do not take it personally....because something you have to figure out and deduce yourself....which makes you better when it comes to problem solving. Now you will forever know this.

And I know that doing something for the first time is fun and a great learning experience....gosh knows I have had millions of them. SO...all I am trying to do is ....as I wrote above...to keep you from messing up.

I am glad you got it in and working.

FOR OTHERS WHOM MAY DO THIS SERVICE OPERATION:
Do not be surprised that when pulling out the shaft of the distributor that it binds and can get stuck. Make sure that when you pull off the gear...that you do not feel any burrs at the end of the shaft. And even if you have no burrs...the shaft can possibly stop about a third the way. Some come out fine...others can be a pain. Being very patient works here.

DUB

 

Well there ya go, you got your own class room!