Is there any possible way to check the Opti to verify if it's good or bad ?
Seems like the shop manual wants to rule everything else out and then say the Opti is bad. Didn't know if it can be directly checked on some kind of device at a shop or not. Needless to say we have the Opti blues, or maybe not, can't determine why i'm not getting a spark.

 

Well you could stick the coil wire up your nose and crank the engine and see what happens

Seriously though:

* Things You'll Need:
* 2 water pump gaskets
* Razor blade
* Teflon thread sealant
* Shop rags
* Vice grips
* Catch pan
* Socket wrench
* Breaker bar
* 10 mm short socket
* 10 mm deep socket
* 6-inch extension
* 16mm wrench
* 9/16-inch socket
* 13mm wrench
* 5/16-inch socket w/ extension
* 11/32-inch socket
* Masking tape
* Marker








You would need a power supply and DVM. I suppose an oscilliscope could also be used to check the high and low resolution pulses if you have something to continually spin the Opti driveshaft.

Here is an On Car method of testing. You could extrapolate what is needed to do this off car as well.


The opti has two functions in the spark process. The first thing that happens is as the cam turns, the optical section of the optispark picks up the signals by the rotation of the shutter wheel. The pulses are sent to the PCM via the optispark electrical harness. The PCM processes the signals along with other sensor input and determines the proper time for the coil to fire. The PCM sends a signal to the Ignition Control Module (ICM) and it, in turn, causes the coil to fire. The spark from the coil travels through the coil wire back to the secondary ignition section of the optispark (cap and rotor), to be distributed to the proper cylinder.

If the opti is never sending the signal to the PCM, the PCM will never send a signal to fire the coil.

Here is some testing you can do. Refer to this diagram:



Disconnect the ICM connector. Leave coil connected.
Turn key to ON.
Check for dc voltage with a digital meter at harness terminal "A" to ground and and also "D" to ground. Note: Use a high impedance meter (at least 10 megohm) when dealing with the PCM.
Result should be 10v dc or more on both terminals. If you get no voltage, use the diagram and chase back toward the coil and the ignition fuse. Power for the ICM comes from the ignition fuse and through the coil, so any of that could be bad.
If you have good voltage, switch the meter to ac scale and connect test leads to terminal "B" and to ground. Observe meter while cranking the engine. You should see between 1 and 4 volts ac (those are the pulses that trigger the coil to fire).
If you don't see the proper ac voltage the problem could be the optispark, the harness to the optispark, the PCM or any of the wiring in between. Visually inspect all the connections you can get to for poor contact or corrosion.


If you are successful using an oscilliscope, this is what the pulse train output should look like from the high and low resolution timing wheel:



if it is the opti -spark you would get a low or high res code.

16---low res



36—high res


On the bench, the four tiny bolts holding the distributor cap to the Opti housing are more apparent. They use an unusual inverted Torx-style head, which most of us don't have a tool for. The techs at MSD claim the company'scap and rotor sets will include the required tool, but our test cap didn't. We used a trick we found on the Internet of using one of the throttle-body top plate screws as a socket. Wrap the screw in tape to protect the threads and then clamp it with a small vice grip. Now it can be used to remove the Opti's bolts. Note: The likelihood of the throttle-body screw's threads being damaged is high. View Related Article


here is a proceedure to troubleshoot the ignition system........

Step 1. Connect a spark plug tester to a spark plug wire and
check for spark while an assistant is cranking the engine.
Check each plug independantly. this checks for open
spark plug wires. Spark in one or more than one wire
indicates the problem is in spark plug wires or optispark.
If no spark exists, go to step 2.

Step 2. Check for spark at the coil wire with the spark tester
while cranking the engine. A spark indicates the problem
is in the distributer (optispark). If no spark go to step 3.

Step3. Perform check on ignition coil.
a: Unplug coil electrical connector and check pink wire for
12v. If power go to b.
b. using ohmeter low scale, hook up the leads to the
primary terminals on the ignition coil. Should indicate
very low resistance. If not, replace coil.
c. Using the high scale, hook up one lead to the primary
terminal, the other to the secondary terminal. Should
not read infinite resistance. If it does, replace coil.

Step 4. Disconnect the ignition module connector and with the
key on, check voltage at terminals A and D on the harness
side of the connector. (pink/black and white/black wires)
If under 10 volts check for faulty circuit from the ignition
module to the coil or check for grounded external coil
circuit. If 10 volts or more, change the voltmeter to a/c
scale and measure voltage on terminal B while engine is
cranking. (white wire). If 0 volts, Have ECM checked. If 1-
4 volts, with the key off, disconnect the module
connector. Install a LED type test light on the positive
battery terminal and probe terminal C on the harness side
of the connector (black wire). The light should illuminate.
If not, check ground wire in the harness to the module. If
the test light is on, go to step 5.

Step 5. Remove the coil wire from the coil and ground it to the
frame. Connect LED test light into the optispark harness
connector red wire terminal C. The harness connector that
you will use is located on the passenger side of the
engine up near the fuel rail. You will need to insert a back
probe pin into terminal C. If the test light flashes when an
assistant cranks the engine, the optispark is suspect. If
no flashes, replace the ignition module.

If the above tests results are correct and there is still no
start, it is tough to to tell the difference between a
faulty module or optispark. Module = Cheap$$, optispark
=moderate $$$.


The whole deal with the optispark is that due to the location, is prone to water contamination. There are two designs. The first is a non vented. It is a sealed (supposedly) system. As electrical energy travels though the distrubuter, ozone builds up within the unit causing corrosion. The second design is a vented system that keeps the opti in a low pressure environment so that the ozone cannot build up within the unit itself using vacuum lines attached to the opti and the intake vacuum circuit. The problem is that the location of the unit hasn't changed. I've found that in order to get the most life from the stock opti unit, dielectric grease must be used on all spark plug wire connections to seal out water and a 90º fitting screwed into the weep hole on the water pump. This weep hole allows water to start leaking as the water pump's bearings and seals wear, unfortunately this weep hole is right above the opti! A 90º fitting and a length of vacuum tubing routed around the opti and below it will re-direct the water when it leaks, saving the opti from contamination.


OPTI and Spark Test


The opti has two functions in the spark process. The first thing that happens is as the cam turns, the optical section of the optispark picks up the signals by the rotation of the shutter wheel. The pulses are sent to the PCM via the optispark electrical harness. The PCM processes the signals along with other sensor input and determines the proper time for the coil to fire. The PCM sends a signal to the Ignition Control Module (ICM) and it, in turn, causes the coil to fire. The spark from the coil travels through the coil wire back to the secondary ignition section of the optispark (cap and rotor), to be distributed to the proper cylinder.

If the opti is never sending the signal to the PCM, the PCM will never send a signal to fire the coil.

Here is some testing you can do. Refer to this diagram.

Disconnect the ICM connector. Leave coil connected.
Turn key to ON.
Check for dc voltage with a digital meter at harness terminal "A" to ground and and also "D" to ground. Note: Use a high impedance meter (at least 10 megohm) when dealing with the PCM.
Result should be 10v dc or more on both terminals. If you get no voltage, use the diagram and chase back toward the coil and the ignition fuse. Power for the ICM comes from the ignition fuse and through the coil, so any of that could be bad.
If you have good voltage, switch the meter to ac scale and connect test leads to terminal "B" and to ground. Observe meter while cranking the engine. You should see between 1 and 4 volts ac (those are the pulses that trigger the coil to fire).

If you don't see the proper ac voltage the problem could be the optispark, the harness to the optispark, the PCM or any of the wiring in between. Visually inspect all the connections you can get to for poor contact or corrosion.


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Remove the cable from the negative battery terminal with a 5/16-inch socket or wrench. Loosen the nut on the cable clamp and slide the clamp off the terminal.
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Step 2
Remove the air intake ducting. Use the 5/16-inch socket to remove the screw bolt connecting the elbow on the intake to the air filter housing.
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Step 3
Disconnect the wires running to the mass airflow sensor and pull the air filter housing off.
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Step 4
Remove the two screws holding the thermostat housing to the water pump with the 5/16-inch socket.
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Step 5
Place a catch pan underneath the radiator.
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Step 6
Fold the upper radiator hose out of the way. If coolant leaks make sure the catch pan is positioned under the radiator to catch any drips.
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Step 7
Get under the vehicle and open up the valve on the bottom of the radiator on the passenger side. The release valve on the radiator is usually made of plastic on GM vehicles, and it looks a little like a wing nut. Use the vise grips to remove this wing nut, but be careful not to damage the nut, as it will break from applying too much torque. Close the valve when all of the coolant is drained from the system.
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Step 8
Loosen the three bolts that hold the crank pulley in place but do not remove them.
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Step 9
Remove the bolts on the idler pulley with a 13 mm wrench.
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Step 10
Remove the three bolts from the crank pulley and remove the pulley.
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Step 11
Disconnect the positive wire lead from the passenger side cooling fan.
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Step 12
Remove the four screw bolts holding the passenger side fan with a 10mm socket.
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Step 13
Disconnect the positive wire lead from the air pump.
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Step 14
Remove the three screws from the air pump holding it to the bracket with a 10 mm deep well socket.
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Step 15
Disconnect the electrical connection running to the coolant temperature sensor on the water pump. Remove the two plastic fasteners from the water pump.
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Step 16
Remove the two air pump-to-engine-block bolts with a 9/16-inch deep socket.
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Step 17
Loosen all of the hose clamps connected to the water pump with a pair of vise grips. Pull the hoses off and allow the coolant to drain into the catch pan.
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Step 18
Remove the 5 bolts that are accessible on the water pump with a deep well 9/16-inch socket. Remove the last bolt using a 6-inch extension and a 9/16-inch socket.
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Step 19
Pull the water pump off.
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Step 20
Mark the location and orientation of all of the spark plug wires with tape and a marker. This will ensure that you reattach the plug wires in the correct order and location.
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Step 21
Remove the plug running to the old Optispark unit. and remove all of the plug wires running to the top of the Optispark. Remove the three screws holding the Optispark to the timing cover with a 10 mm socket. Pull the Optispark off.
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Step 22
Install the new Optispark. Installation is the reverse of removal.