welli bought my 94 z28 B4c ex poilce car without spark, the connector going into the opti spark wa chewed in half by rats (car sat since 03) well i fixed the connector, and still no spark, i hook power to the exposed parts of the wires and when the key is on (if im right on the colors) the purple and white one turns the fuel pump on, but only if its mathed with the red and black wire, if i connect power to the solid red wire it turns the gauges on even with the key off and out of the ignition,.. and the tan and black wire is a ground....


so now im getting fuel just no spark.... is there anyway i can test the optispark and coil out?

is there a way i can run a hot wire from the battery to anything to give it spark? just so i know the car runs.... i traded my running 86 z28 convertible for this..... and i really just wanna get it started to see if it was at all worth it or if im a total idiot for trading this....

if anyone can help me out please do, if you can text me 313-573-9333

or if anyone lives around the 94 and telgraph in taylor area..... please come check this thing out and help me with it.... i have no clue on anything to do with spark on this car..... if it had a distributor i would just run one from the battery right into the thing and it would start but im clueless on this opti spark stuff...... HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!

 

and theres this mystery connector unplugged by the pcm under the hood..... its got a yellow rubber seal and has 5 wires going to it, looks like a rectangle, and its too short to go past anything further then the shock tower....... ideas???

 

Do the test for diagnosing a bad opti at the top of the threads page it is a sticky.

 

Are you talking about the Opti harness?

The red wire supplies the Opti cam position sensor module with 12V from the PCM. The pink/black wire is ground. Red/black is the output wire for the 5V square wave low resolution pulse signal from the cam position sensor. Purple/white is the 5V square wave high resolution signal from same. I wouldn't go hooking up any kind of power to the signal wires - you will probably fry the cam position sensor.

The Opti does not control the fuel pump directly. It just sends the cam position signal to the PCM. The PCM will kill the fuel system if it does not see the 5V square wave low resolution pulse signal from the Opti cam position sensor after two crank revolutions, because it has no way of knowing where the engine is in its rotation, so it can't time the ignition or the injectors.

 

yes im talking about the opti harness.... the computer isnt sending out any signal through the white wire going to the ICM..... not even while cranking...


and ive heard that the 94 lt1s dont have cam and crank sensors? is this true??????


tell me what all i should check? what sensors???? what connections??? right now i have my wiring harness being re wired thinking its something in there.....


so if you or someone else can give me a list of things to look for id really apreciate it......


and if someone has a wiring harness for the interior of my car they would like to trade or sell let me know, my cars specs are below.



power mirrors, windows, locks, hatch pop, seat, my car has EVERY power option for this car, i need the harness from the firewall back to the hatch if possible... MUST BE OBD1!

 

The opti is the cam sensor, there is no crank sensor on OBD1 cars nor is it needed.

Check the harness to the opti that runs along the PS of the intake manifold....look closely at the pins at the grey connector and at the opti end. You're looking for bent pins or corrosion. Check each wire for continuity. If the wire checks out test the OPTI as outlined in the sticky at the top of this forum page..

 

ive done the opti test for the car and i couldnt get past where it says to check for power going to the white wire that leads to the ICM


now if theres no power to that wire does it mean my opti is bad???

the car has sat since 2003..... so i think its time for one anyway....



now a new problem has poked its head out,.


the car will no longer crank, theres no security light coming on at all.... bulb isnt blown....

when i turn the key over it acts like your trying to start it while in drive, no crank, no nothing..... any clues? im thinking vats system.... im thinking about re wiring the inside too

 

Have you scanned it for codes? If the optical cam position sensor in the Opti is bad, you will get DTC 16 and DTC 36.

 

I havent tried pulling codes. But the service engine soon light doesnt come on at all... so i was thinking it was the computer. But come to find out its my wiring harness. But im still not sure about any codes.

How can i pull codes? Do i need the obd1 computer thing to get them? Oh and also will a 98-02 camaro z28 gauge cluster work for my 94?

 

Did you check for it with your meter set to the proper AC scale?


No it does not automatically mean the opti is bad.

Well you been cranking the engine but have you recharged the now depleted battery?

There are codes that do NOT set a SES light. One of them is the dreaded DTC16 which Fred alluded to earlier. This is the loss of the low res feedback signal from the Opti to the PCM. Without it, the PCM shuts off the injectors.

When you checked for the loss of spark did you check a few plugs and then go directly to the coil to confirm the coil was not sparking? Or did you merely pull one plug?

Have you confirmed your injectors aren't firing while you're doing all this cranking and checking? If they are, you may have another reason the engine now wont crank.

What you need to look at is the low res feed back signal from the opti to see if it has 5V DC on it. It was referred to earlier as the Red/Black wire. The mere fact that it is there does not necessarily mean it's pulsing like it should. However if it is not there, you know then you have to confirm the opti is getting 12 volts and ground. If you have no 5v but 12 volts and ground are there, then the optical sensor in the distributor is dead.

What kills these things while they sit is condensation. My 94 would never start on a cool humid morning like today. But later that afternoon, no problem. Middle of winter no problem. Only cool humid mornings.

 

ive checked it all, the coil will spark but only if i tap a power wire onto the white signal wire.... my injecters wont kick at all not even for a second unless i have a power source going to the white signal wire from the computer.... im not getting any power to the opti harnes exept for when the key is on and thats only the solid red wire and thats to the gauge cluster.....

other then that i have NO POWER i have checked it for ground and its got a good ground.... i cant figure this out....... i just picked up a new wiring harness inside and out.... and a new coil and icm so hopefully once i install all of that i will get it running... if not, anyone got a spare opti forsale or trade? need a non vented for a 1994 z28, car was off the line in june or july so one thats for around those months please... text me if you got one, 313-283-6793

 

Really hard to follow most of what you describe.

The only red wire in the Opti harness is the wire that runs from PCM pin B14 to pin B on the Opti. There is no red wire that connects the Opti harness to the "gauge cluster".

Do you mean you are connecting 12V to the white wire from the PCM to the ICM? Do you realize that there's a good chance you are going to damage parts that are not designed to see 12v?

Ditto... you can't randomly apply 12V to various bare wires and assume you are not going to damage parts, as I already mentioned.

So let's try this again - HAVE YOU SCANNED IT FOR CODES?. As already mentioned, the key code we are looking for DTC 16 does not turn on the SES light.

At this point, its just a likely you have damaged the PCM, the ICM or the optical module in the Opti by applying 12V to the lower voltage signal wires.

 

Throw 12 volts at everything, then replace it all. Saweeet. I wish I had that kind of money. Doubt that will fix it but sweet none the less.

Good luck

 

I'm at the point where I am questioning the validity this whole thread. A week after he posted this question, he posted parts for sale on this forum. I moved it to "parts for sale", and it has turned into a huge arguement. And now we are getting "report this post" notices from other members.

 

yeah anyone ever think i had extra parts i bought for this car thinking it was something simple?

and i have a all new wiring harness, pcm, coil, and icm for the car... and im going to pick a opti up today....


im going to try and swap everything over within the next week, so ill try again later... ill repost with updates as i go along...