Fuel Pressure Test
Thread Starter
Burning Brakes
Joined: Apr 2005
Posts: 973
Likes: 0
From: Chico California
Since these are history codes I would suggest to disconnect the neg cable on the battery for a minute and reconnect or pull the ECM fuse. This will clear the ECM's memory and you can start fresh. Start the car and see if any of these codes come back. Remember to write down what module these codes came from to help in the diagnosis (1,4,or 9).
The code 16 is not good and usually points to a dying opti spark.
These two are in module 4 (ECM)
Code 16...optispark low resolution (fuel)
Code 42...EST (knock sensor) grounded
This one is in module either module 1 or module 9
Code 74 module 1 (CCM)...LED display open
Code 74 module 9 (ABS/ASR)...Low voltage
The code 16 is a good indication as to why the engine dies. You will need to make sure what module these codes are in (it will tell you what module the code is in on the speedo display). You need a FSM to diagnose each code starting with the lowest code first. Sometimes multiple codes can be the result of one failure or wiring problem and fixing the lowest code first might remove another code. I could help but sold my 92 last month and gave the FSM with it.
http://www.c4guru.com/articles/CCMCodePull.pdf
The code 16 is not good and usually points to a dying opti spark.
These two are in module 4 (ECM)
Code 16...optispark low resolution (fuel)
Code 42...EST (knock sensor) grounded
This one is in module either module 1 or module 9
Code 74 module 1 (CCM)...LED display open
Code 74 module 9 (ABS/ASR)...Low voltage
The code 16 is a good indication as to why the engine dies. You will need to make sure what module these codes are in (it will tell you what module the code is in on the speedo display). You need a FSM to diagnose each code starting with the lowest code first. Sometimes multiple codes can be the result of one failure or wiring problem and fixing the lowest code first might remove another code. I could help but sold my 92 last month and gave the FSM with it.
http://www.c4guru.com/articles/CCMCodePull.pdf
I cleared the previous codes by disconn. battery. Started the motor with the paperclip still in place and got no codes. After about 5 minutes, engine died. Fuel press. was good.
I removed the clip, started and as usual it dies.
Re-inserted paperclip for the codes and got code H36 on the #4.1 module.
I also got a code on the ASR on the 9.7 module.
It appears my opti is toast.
As to the previous codes I posted, they never came back.
I wonder if I got a code reader to plug in if I could do better??
Suggestions - Comments - Advice ????
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
No need for a code reader if you have a paperclip, the link I posted, and a FSM to follow. It appears that your opti is on it's last leg. The code 16 and 36 say so. Usually if these two codes appear, the opti is gone. I would suggest to troubleshoot both these codes following the FSM. It will only confirm the suspecion. Other than bad connections at the opti or wires, which the FSM will let you or not, the opti needs replacing. Do the troubleshooting tests and confirm it to make sure.
Thread Starter
Burning Brakes
Joined: Apr 2005
Posts: 973
Likes: 0
From: Chico California
No need for a code reader if you have a paperclip, the link I posted, and a FSM to follow. It appears that your opti is on it's last leg. The code 16 and 36 say so. Usually if these two codes appear, the opti is gone. I would suggest to troubleshoot both these codes following the FSM. It will only confirm the suspecion. Other than bad connections at the opti or wires, which the FSM will let you or not, the opti needs replacing. Do the troubleshooting tests and confirm it to make sure.
Safety Car
Joined: Aug 2004
Posts: 4,908
Likes: 735
From: Southwest Kansas
2022 Corvette of the Year Finalist -- Unmodified
2021 C6 of the Year Winner - Unmodified
I guess that I can only add that replacing the Opti isn't all that difficult....time consuming but not difficult. Do a search there's lots of info on replacing it. BTW I bought a Genuine GM from thepartsladi on Ebay, the best price I found, I went ahead and changed out the water pump at the same time... again a Genuine GM pump from thepartsladi. I just checked the listings and didn't find the pump or opti for a 92, but they say in the ads to call them if you need a part that is not listed. Here's the number 334-493-1240
Thread Starter
Burning Brakes
Joined: Apr 2005
Posts: 973
Likes: 0
From: Chico California
I guess that I can only add that replacing the Opti isn't all that difficult....time consuming but not difficult. Do a search there's lots of info on replacing it. BTW I bought a Genuine GM from thepartsladi on Ebay, the best price I found, I went ahead and changed out the water pump at the same time... again a Genuine GM pump from thepartsladi. I just checked the listings and didn't find the pump or opti for a 92, but they say in the ads to call them if you need a part that is not listed. Here's the number 334-493-1240
Many thanks for the information.
