Testing Opti For High Res Pulse 1992?
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Yes, and I have done it. Any oscilloscope will work due to the low frequency. I slid a pin down along side the wire of terminals A and B of the opti connector. This will enable you to keep all connected as it should be. Then just probe each pin for the pulse you want, A is low and B is high. They are at TTL levels, 4 to 5 volts. Be careful not to short anything out. 
Changing the RPM changes the frequency.
I would not tell anyone to do this that did not have the technical ability, proper tools and documentation. Good electronics knowledge and practices should apply here. You can imagine what damage can be done. The high resolution is just a square wave of equal pulses and the low resolution is square waves of varying widths as relating to the different cut outs in the disk. Its pretty neat though to look at. You can also scope the ignition control drive, pin B (white wire) of the ICM (output of the PCM) . Best of luck, have fun.
Changing the RPM changes the frequency.I would not tell anyone to do this that did not have the technical ability, proper tools and documentation. Good electronics knowledge and practices should apply here. You can imagine what damage can be done. The high resolution is just a square wave of equal pulses and the low resolution is square waves of varying widths as relating to the different cut outs in the disk. Its pretty neat though to look at. You can also scope the ignition control drive, pin B (white wire) of the ICM (output of the PCM) . Best of luck, have fun.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
The bottom line is thus - if you are getting an H36 DTC, then there are one of two real posibilities:
1) The harness to the opti has been compromised.
2) The opti is dead, long live the opti.
That's it. Nothing else can cause that code.
1) The harness to the opti has been compromised.
2) The opti is dead, long live the opti.
That's it. Nothing else can cause that code.
Le Mans Master
Joined: May 2005
Posts: 7,359
Likes: 2,281
From: Central Maryland
Originally Posted by bogus
The bottom line is thus - if you are getting an H36 DTC, then there are one of two real posibilities:
1) The harness to the opti has been compromised.
2) The opti is dead, long live the opti.
That's it. Nothing else can cause that code.
1) The harness to the opti has been compromised.
2) The opti is dead, long live the opti.
That's it. Nothing else can cause that code.
I'd add that there are two other possible causes, though they are far more obscure & unlikely:
1. A dead input on the high-res signal line in the ECM.
2. Tom Piper has posted here that he's seen a case or two where the coil wire was running very close to the Opti harness, and either arcing over to, or inducing enough hash into, the Opti harness to trigger bogus Opti codes (he also noted that the '92 C4 had a shield on the Opti harness that should prevent this -- this shield was eliminated beginning in '93).
Be well,
SJW
Melting Slicks
Joined: Jul 2006
Posts: 3,356
Likes: 1
From: Chesapeake Va
hi res
Originally Posted by pcolt94
Yes, and I have done it. Any oscilloscope will work due to the low frequency. I slid a pin down along side the wire of terminals A and B of the opti connector. This will enable you to keep all connected as it should be. Then just probe each pin for the pulse you want, A is low and B is high. They are at TTL levels, 4 to 5 volts. Be careful not to short anything out. Changing the RPM changes the frequency.
I would not tell anyone to do this that did not have the technical ability, proper tools and documentation. Good electronics knowledge and practices should apply here. You can imagine what damage can be done. The high resolution is just a square wave of equal pulses and the low resolution is square waves of varying widths as relating to the different cut outs in the disk. Its pretty neat though to look at. You can also scope the ignition control drive, pin B (white wire) of the ICM (output of the PCM) . Best of luck, have fun.
Changing the RPM changes the frequency.I would not tell anyone to do this that did not have the technical ability, proper tools and documentation. Good electronics knowledge and practices should apply here. You can imagine what damage can be done. The high resolution is just a square wave of equal pulses and the low resolution is square waves of varying widths as relating to the different cut outs in the disk. Its pretty neat though to look at. You can also scope the ignition control drive, pin B (white wire) of the ICM (output of the PCM) . Best of luck, have fun.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Originally Posted by SJW
In almost all cases, a Code 36 will be as Andy noted -- either a dying/dead Opti or an Opti harness fault.
I'd add that there are two other possible causes, though they are far more obscure & unlikely:
1. A dead input on the high-res signal line in the ECM.
2. Tom Piper has posted here that he's seen a case or two where the coil wire was running very close to the Opti harness, and either arcing over to, or inducing enough hash into, the Opti harness to trigger bogus Opti codes (he also noted that the '92 C4 had a shield on the Opti harness that should prevent this -- this shield was eliminated beginning in '93).
Be well,
SJW
I'd add that there are two other possible causes, though they are far more obscure & unlikely:
1. A dead input on the high-res signal line in the ECM.
2. Tom Piper has posted here that he's seen a case or two where the coil wire was running very close to the Opti harness, and either arcing over to, or inducing enough hash into, the Opti harness to trigger bogus Opti codes (he also noted that the '92 C4 had a shield on the Opti harness that should prevent this -- this shield was eliminated beginning in '93).
Be well,
SJW
As for #2, I vaguely remember those comments Tom P. made.
