sc1twntrbo

my buddie has a 95 formula and for a week now weve been tryign to get it started. it turns over just wont start. we changed the opti 2 times and changed the coil. we also got the icm checked. i havent checked the fuel becuase im nto even getting spark off the coil or and spark plug wires. ive checked the fuse. what else could it be.

slopokrodrigez

Check to see if your getting power to the coil on the pink wire. If ok, Then check A and D terminals of the ICM to see if they are more than 10 volts. If they are low, disconnect the ICM and check just the plug while it's not connected to see what voltage you have. If the voltage is bad with the connector off, then the coil is bad. If the voltage is bad only when connected then the ICM is bad.

Terminal C of the ICM should be at ground. check from there to the positive battery terminal for 12 volts.

Now you want to check the ign control signal from the pcm to the ICM. While cranking the engine, use the AC scale on the dvm and check from terminal B of the ICM(should be the white wire) to ground there should be 1 to 4 Volts AC there.

After you check those items, let us know what you find.

Your problem will more than likely be in the above tests.

BTW, be sure you use heat sink compound on the ICM when you put it back or replace it. It's available at Radio Shack.

StrkdFormula383

i am the friend w/ the piece of **** car that will not start. today we did some test w/ the dvm. i catn remember all the numbers, but i remember that there are 4 wires that go from the opti to the pcm. 2 should be 5 volts and the others should be positive(not sure on volts). the two 5 volt wires were good, but only one wire was positive. the outer wire that should be pos. was not and would only pick up like .003 volts if that. Aperently the power goes from the pcm to the coil into the icm and back to the coil and into to opti to distribute spark from there. power seemed good going into the icm but not coming out. so we changed the icm that tested good w/ a new one. and the car will still not start. i did not have the dvm after i got the new icm so i dont know what the numbers are but i know the damn car will still not start. this is one thing i do have that is wierd. at the end of the plug wire that leaves the coil there is a very very small spark that i can get to ground. i had a screw driver in the end of the wire and tried to ground it. i did not see any ark except for when i tuched the screw driver to ground. the ark was honestly no bigger than a statick spark when you tuch a door **** or something, if even that big.VERY VERY SMALL! so, that is where i stand now, please reply if you know anything more. slopokrodrigez, if you would, please send me a e-mail or a phone number, you seem to know your **** and i would like to talk to you more about the problem. Thanks

slopokrodrigez

My name is Dave, my email is jamianddave@charter.net. Your welcome to call me at home after 6pm eastern time. Email me for my phone number. Warning, I live in VA and it may be expensive to call. I will be leaving the area to go "home" for thanksgiving mid day wednesday.

Let's see what we can figure out. The wires that go from the PCM to the opti are voltage and a low reference and 2 lines that pulse. The pink/black is low reference but not necessarily ground. The red wire is supply voltage. One of the other 2 is the low resolution and the other is the high resolution signal. These are pulses. Like a square wave. You couldn't see these pulses with a meter. They move too fast. Don't even try. Let's assume these are ok for the time.

Check the black wire to the ICM (pin c)to be sure it's grounded properly. Now check the pink/black(pin a) wire and also the white/black (pin d)wire to the ICM with the key on. These 2 points should have at least 10 volts. You must check these to see what they are. Your wiring colors may be off. Books are notoriously wrong since no one updates them.

The last thing we want to check is with the meter set to AC. All the previous readings should have been done with the meter set to DC. Now check the signal wire from the PCM to the ICM it should be a white wire on pin B of the ICM. It should be between 1 to 4 volts when checked to ground.

If you check the AC signal and it is not correct, try disconnecting the wire and check it again. Remember that when a signal travels between 2 items, you don't know if it is being killed by the item receiving it, or if it isn't being sent out. That is why you would disconnect the coil to see if it is there.


If you'll do these tests exactly, we can continue from here if they are ok and WE WILL figure this out. It will just take a little patience. I hope you have another car to drive.

I'll check my mail when I get home at 6 tonight. Good luck. I'm with you.

You can call me at work during the day at 757-826-8471. I own the business so I won't get in trouble MUCH. LOL

StrkdFormula383

but what is the deal w/ the small spark i am getting from the coil. that part i dont understand. i would think it should be all or none. the only thing i could think of is maby the new msd coil is not in good working order because apperintly spark is making it to the end of the coil, not much but some.??? i need to unplug the plug wire from the coil and see how the coil arks, cause maby i am loosing the spark throw plug wire, maby it is bad although it is not but a year old 8mm tayler wire? any ideas?

slopokrodrigez

Even the shop manual tells us to use a spark tester. The tester you must use moves the contacts further away from each other since it is not under compression from the cylinder. Compression makes it harder to jump the gap so the tester mimics this by moving the contacts further away. If you don't have access to a tester than take a NEW plug and open the gap up to about 60 to 80 thou. Then plug in the coil directly to the test plug. If that sparks then check each plug wire with the tester. You do not have to remove the plug in the cylinder you are testing unless you find all the wires produce spark. You should however check the plugs for fouling. Running rich for example will eventually foul a plug to the point it won't fire.

I would ask that you still do the voltage checks that I mentioned so we can exclude them as causes and move on. For example, if the voltage going to the coil is low than spark energy will be low.

Let me know what you find

tanker

Check all your grounds,once after putting an engine in, I forgot to connect one, I my car didn't start too. I know the feeling of having a car and not being able to start it, hope you get it running soon.

StrkdFormula383

alright dave, first time this has looked good. made lots of progress tonight i think. started doing other test and what not. tryed to show my frien the small ark i was talking about coming from the coil and found that not only was the ark the size of a stativ spark or something but, that all it is is static electricity. the car can be completely off and i can get some static, so i guess the coil just gives off static. anyways, so that is out of the pic. i have no spark. now... we where doing some test w/ the dvm and when i went to mess w/ the conection that is on the harness from the opti to the pcm it made a funny noice when i unplugged it, whitch it had done many times before but, never gave it any thought. tonight i thought about it and thought maby i heard an ark. so w/ the car off i unplugged the plug wire from the coil. than played w/ the conection. i sall one big blue spark. so than... i had my friend turn over the car while i played w/ the connection and the coil would ark to what ever it could around it. but not a consistant ark. so than i tried to get an ark at the end of a plug wire that goes to a plug. and it would not ark. so i came to this guess. i figure that the connection is crappy and that it would not likely ark at the plug cause it was not consistant spark. i figured the only way it would ark is if we got lucky enough to time the good connection w/ the coil fire at the same time that that number cylinder is supposed to fire, whitch i figured whould be unlikely. so this is what we did. one by one cut off the wires at the connection and put a piece of new wire in place of the connection. so now there is 4 solid wires that go from the opti to the pcm, and not a connection in the middle. now dont ask me why. but, the car or the coil will not fire at all any more. we used the dvm to make sure the connection is good and it is. and i know i did not mix up any wires. so now im kinda lost. im glad cause i think i have it narrowed down, but i dont now why w/ no connection piece the car will not fire. i dont now if the thickness of the wires need to all be the same as the old wires. or if the connection has something more it does, i have no idea. we tersted the connection w/ the dvm and the wires do not cross or tuch internaly. so i dont know what else it could be. please let me know what you think, im guessing i will need to buy a whole new harness from opti to pcm!? what do you think?

slopokrodrigez

Is there a reason why you keep skirting around the tests I mentioned? Are the instructions confusing? Are the wire colors different than I explained? DO THE TEST. Give us the results when you do.

I will tell you this, if you keep doing arcing with the wires from the PCM to the Opti, you're gona damage the PCM. The components in the PCM don't like static. Some of the components in the PCM don't even like the voltage from a DVM. (the ohms scale uses voltage from an internal battery).

If you want to check the feedback signals from the opti, you can do that. Since you changed the opti 2 times we can safely assume that it is not the problem. Connections from it to the PCM maybe the problem but you don't need tools to check or fix that type of problem. I suspect you have a more rudimentary problem.

After you do the checks I asked, I will go from there.

The order of events can be to first check the AC signal from PCM to ICM. If it's there, the problem is in the ICM or coil. If it's not there, the problem is in the PCM/ Opti or the wiring between it. So you see the AC test on the white wire from the PCM to the ICM(pin B) is critical. This paragraph is key. Read this paragraph several times if you have to.

We can not go any further without the tests I mentioned. Sure you can look for bad connections or wires visually, and you should but that should have been done before you ever sat down at this bulletin board. What I'm attempting to do is take the ignition and devide it in half. That way you only have to diagnose 1/2 at a time.

Here is the test for the opti. pull the harness off the opti. with the power off. Check pin D(pink/black) wire continuity to gnd. Turn the ignition on and check pin C(red wire) it should light a test light. Turn the power off and reconnect the opti. Turn the power on and check both pins A (red/black wire) and pin B (purple/white wire). They should be about 5 volts. If they are not, try rotating the engine and check them again. Do not jump to conclusions if you test the PCM and don't find the above conditions. Remember what I said about the signal between 2 items. You don't know if it isn't coming out of one or if the other is killing it from entering.

I'm leaving town today but will try to check the board while I'm gone. If you need more help and I'm not around then Rob can help you but YOU MUST HAVE A METHOD TO YOUR MADNESS. Don't just continue to poke around haphazardly. It's harder for us to help you. One last thing that may help you see what we are trying to do. Go here and look at the ignition circuit.

http://www.e-toolbox.com/ads/rq.cfm

When you get there, choose wiring diagrams, then pick figure 15 (3 of 3). The coil and ICM are on the right about 1/3 way down.

You can also check the distributor drawing on figure 13 (1 of 3).

See ya

sc1twntrbo

we did the test put he is stuborn and doesnt like the results. im at home and dont have the diagram in front of me. but here are the results.
A=11.99 volts.
D=11.99 volts.
the ground was more than 12v.
and i got under .03 for the pcm wire.
Now the wiring harness went ABCD on his car not CADB like in this diagram http://shbox.com/1/95_ign_system_schematic.jpg
i got my lettering off the harness that went to the icm. i tested it by stickinn a sewing pin into the wire that pluged into the icm and tested it.
i hope this helps

StrkdFormula383

the link you sent me i can not see, you have to be logged in or something. we did the test already. there is not a 1 ot 4 volts coming from the pcm to the icm. there is another list of test that we have beem following (about the same as yours) and it breaks down to be the opti or the pcm, or obviously connections. on the four wires you mention, the two 5 volt wires are good, and as far as the other 2 go, one is like 12v(the other inner wire that is not 5 volts) and the other has like low to no volts(the far outside wire that is not a 5 volt wire). so there are all the numbers we have right now. but i still think it is something in this connection in the middle of the harness. after the connection was cut off we pluged it together and checked each wire to see if there was current all the way throw the connection. they where all good except on the for pnk/blk wire, we could only get a current throw the connection when we moved around the wire, so i strongly think that is where the problem is!?

StrkdFormula383

OK. here is where i am. today we tested the opti. the conection and thw whole harness. all the way from the plug in at the pcm and the plug in at the opti. i figured out how to get the coil to ark. the connection was bad between the 2 and by wiggleing it we where getting a connection and than loosing it. we figured this out by undoing i belive the pnk or ppl and blk wire. while turning over the car we tuched the wires together. only when we tuched did we get an ark and than another ark when we disconnected them. but it would not ark if they where held together. i dont know why that would make the coil fire. my cause is maby we where mimicing a signal or something from the opti, i really dont know, because if that was why than i think that would mean the opti is ****. who knows. anyways... i am going to get a new pcm for these reasons. (1)we have replaced everything else. (2)we have checked all the wires that go from one thing to the other. (3)my car is has been converted to a 383 stroker and has completely stock tuning, so i can just by a tuned pcm and still benifit. so... i guess thats it, i wil get the new pcm and if it does not start i still gane tuning and than can be sure it is the opti. but, everything we have done to this point, points to the pcm. so i think(pray)(hope)(better) the car will start w/ a new pcm. Let me know what you think? do you think it is the pcm too? why do you think the coil would fire when we just tapped the wires?
Thanks alot for the help so far!!!

StrkdFormula383

got pcm on order? still waiting!

StrkdFormula383

i got my pcm today! and the damn thing still wont start so i kicked the **** out of it and gave up! its going to the shop!!!

Thanks for all the help everyone!