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Old 07-30-2011, 05:56 PM   #1
mintc
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Default ways to test opti signals to ecm

im trying to figure out how to test my reference signals from my 1992 opti to the ecm is there any other way besides a lab scope to c if that part of my opti is working?
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Old 07-30-2011, 06:05 PM   #2
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Shoebox has an easy test for the Opti. He uses the AC scale on his meter to check the pulses to the ECM. Here's how.

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) to protect 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 (not common) or any of the wiring in between. Visually inspect all the connections you can get to for poor contact or corrosion.

At the end of the optispark harness (disconnected from the opti) with the key ON, you should see:

A = ~5vdc
B = ~5vdc
C = 12vdc or system voltage
D = ~0 - 0.2 ohms ground
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Old 07-30-2011, 06:38 PM   #3
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Quote:
Originally Posted by 1963SS View Post
Shoebox has an easy test for the Opti. He uses the AC scale on his meter to check the pulses to the ECM. Here's how.

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) to protect 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 (not common) or any of the wiring in between. Visually inspect all the connections you can get to for poor contact or corrosion.

At the end of the optispark harness (disconnected from the opti) with the key ON, you should see:

A = ~5vdc
B = ~5vdc
C = 12vdc or system voltage
D = ~0 - 0.2 ohms ground
At the end of the optispark harness (disconnected from the opti) with the key ON, you should see:

A = ~5vdc
B = ~5vdc
C = 12vdc or system voltage
D = ~0 - 0.2 ohms ground im looking for the refernce pulse that fires the injecters would that be a b or c and i should have to crank it to c the signal right?
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Old 07-30-2011, 06:58 PM   #4
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Here is a 1 MHz scope for $48.
http://www.seeedstudio.com/depot/dig...els-p-514.html

You can't beat an oscillosope for seeing exactly what is going on with an electronic ciruit. I'll look for some more low cost oscilloscopes, there are some that use your PC.
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Old 07-30-2011, 07:05 PM   #5
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Quote:
im looking for the refernce pulse that fires the injecters would that be a b or c and i should have to crank it to c the signal right?
Yep, put the meter on a low AC scale like 12 volts. Ground a meter lead. (Doesn't matter which one.) Put the other meter lead on terminal "B". Just pierce the insulation. While cranking the engine watch your meter for an AC voltage. That will be the signals to the ECM from the Opti. Make sure you check for DC voltage from "A" and "D" to ground first. That voltage is necessary for the AC test at "B".

It's super easy to troubleshoot but kinda hard to explain. If you need any other help just ask. Good luck
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Old 07-30-2011, 07:58 PM   #6
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http://www.mainstreamtopics.com/foru...rt-diagnostic/
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Old 07-31-2011, 06:42 PM   #7
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Quote:
Originally Posted by jfb View Post
Here is a 1 MHz scope for $48.
http://www.seeedstudio.com/depot/dig...els-p-514.html

You can't beat an oscillosope for seeing exactly what is going on with an electronic ciruit. I'll look for some more low cost oscilloscopes, there are some that use your PC.

That's kinda cool. I'd like a screen that shows more waves though.
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Old 08-05-2011, 01:48 PM   #8
mintc
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ok so it finally cooled off enuff to start with my headache of a car again so i went out to test my opti pulses per instructions i got off another post with key off nothing on c5 or c14, key on c5 had 5 volts c14 had 5, , i couldnt get any at c9 0r c18 any idea were i should look next , i tested at the ecm with opti pluged n
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Old 01-27-2013, 11:27 AM   #9
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Quote:
Originally Posted by mintc View Post
At the end of the optispark harness (disconnected from the opti) with the key ON, you should see:

A = ~5vdc
B = ~5vdc
C = 12vdc or system voltage
D = ~0 - 0.2 ohms ground im looking for the refernce pulse that fires the injecters would that be a b or c and i should have to crank it to c the signal right?
I posted yesterday about the code 51 and no start but cranking.

I've done some tests and I do have a pulsing 2.2 to 2 volt ground b at the ICM during cranking and the other voltages are good there. I also checked at the opti test connector under the passenger injector cover and those voltages seem ok, however the d connector to ground is 25 ohms, not 0-0.2 ohms.

I think I should check for spark next.....

Last edited by 95BLKVette; 01-27-2013 at 03:09 PM.
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Old 01-27-2013, 01:44 PM   #10
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Originally Posted by 95BLKVette View Post
I posted yesterday about the code 51 and no start but cranking.

I've done some tests and I do have a pulsing 2.2 to 2 volt ground b at the ICM during cranking and the other voltages are good there. I also checked at the opti test connector under the passenger injector cover and those voltages seem ok, however the d connector to ground is 25 ohms, not 0-0.2 ohms. There is no ground pulse at the injectors?

I think I should check for spark next.....
So I checked injectors with noid light...they are pulsing!
Checked for spark at plugs....spark is ok!
Checked for fuel at Schroeder valve....none!
Checked for voltage at fuel pump connector, none!

Ecm!
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Old 01-27-2013, 02:14 PM   #11
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Pins A and B are a pulsing DC signal. A pulses 720 times per rotation, B pulses 16 times. (a pulse is on-off, so you may only see 360/8)

You can use a regular multi-meter, set it on DC and see if you have ANYTHING at all coming out of A or B. For the level of troubleshooting you are at, the number of pulses are not important, as long as you see a voltage greater than 2v, it should be good.
To take it a step further, you can use a 3-5v led (mind your current) between ground and pin A or B. It should flash while cranking.
To go to a level to see if you have an even stranger issue, use an oscilloscope. Youre looking for a pattern of even pulses 720/rpm. they should be high for 1* low for 1* of crank rotation. DC square wave... no sawtooth or anything...
The low resolution side will have varied pulses that correspond with cylinders, they are:
1-2*
8-7*
4-2*
3-12*
6-2*
5-17*
7-2*
2-22*
You will have to realize the relationship to cranking speed vs degrees. But either way, you know by looking at your pulse train on the scope that every other pulse should gradually increase. Dont try to get an external trigger from Pin a... just use your scope.

I have another post somewhere here on the forum that is a complete walk through on the optispark test procedure. Search my user name and Opti

To test the High Voltage side of the opti, use a spark gap tester. The caps do fail and they will arc to other cylinders... its a nightmare.

If you include more information as to why you are testing the opti, what your symptoms are, what codes if any have been reported, and what your goal is, perhaps we can all be of more help.


95BLKVette, 25ohms to ground is unacceptable. Check and clean your grounds. Make sure you have the right scale on your meter.
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Old 01-27-2013, 02:15 PM   #12
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Pins A and B are a pulsing DC signal. A pulses 720 times per rotation, B pulses 16 times. (a pulse is on-off, so you may only see 360/8)

You can use a regular multi-meter, set it on DC and see if you have ANYTHING at all coming out of A or B. For the level of troubleshooting you are at, the number of pulses are not important, as long as you see a voltage greater than 2v, it should be good.
To take it a step further, you can use a 3-5v led (mind your current) between ground and pin A or B. It should flash while cranking.
To go to a level to see if you have an even stranger issue, use an oscilloscope. Youre looking for a pattern of even pulses 720/rpm. they should be high for 1* low for 1* of crank rotation. DC square wave... no sawtooth or anything...
The low resolution side will have varied pulses that correspond with cylinders, they are:
1-2*
8-7*
4-2*
3-12*
6-2*
5-17*
7-2*
2-22*
You will have to realize the relationship to cranking speed vs degrees. But either way, you know by looking at your pulse train on the scope that every other pulse should gradually increase. Dont try to get an external trigger from Pin a... just use your scope.

I have another post somewhere here on the forum that is a complete walk through on the optispark test procedure. Search my user name and Opti

To test the High Voltage side of the opti, use a spark gap tester. The caps do fail and they will arc to other cylinders... its a nightmare.

If you include more information as to why you are testing the opti, what your symptoms are, what codes if any have been reported, and what your goal is, perhaps we can all be of more help.


95BLKVette, 25ohms to ground is unacceptable. Check and clean your grounds. Make sure you have the right scale on your meter.
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Old 01-27-2013, 03:04 PM   #13
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Quote:
Originally Posted by 95BLKVette View Post
So I checked injectors with noid light...they are pulsing!
Checked for spark at plugs....spark is ok!
Checked for fuel at Schroeder valve....none!
Checked for voltage at fuel pump connector, none!

Ecm!
Sounds like youre outa fuel lol

You only get voltage at the pump for 2sec when the key is turned and while cranking of above 8-18psi oil pressure. And of course while the car is running.
Check your fuel pump relay.

Check pin number 7 on the red connector, thats the fuel pump relay, dark green and white wire. I think its a 5v signal. if that is not getting 5v when you turn the key on, or its not getting 5v when cranking, you might have a problem with the ecm
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