Hi.
After I started the engine, it was running fine for a while but stopped suddenly. The way it stopped was that of an electric problem, not of an fuel related one.
Also, strangely, when I connected Pin A and B of the ALDL connector, the SES lamp didn't flash any error code. (It just flashed one, one, one...) It didn't flash even code 12, and I suspect this means something is wrong with the ECM.
And there is one more strange symptom. When the SES lamp flashed, the relay for the coolant fan turned on and the fan started to rotate. When the SES lamp turned off, the fan also stopped.

Do you have any ideas? Any opinions would be appreciated. Thank you.

305 TPI stock engine, 1992 Camaro.

 

What happens when you turn the key now? Engine spins over and does not start? Have you checked all your fuses including the one in the engine bay (perhaps by the battery)? Is the rest of the car getting power?

 

Thank you.
Yes, engine spins over but wouldn't fire. Fuel pump and everything else are working. All the fuses are fine.
It's strange the SES lamp doesn't flash any error code, isn't it. At least it should show Code 12.

 

It sounds like a bad ecm , summit racing isn’t priced to bad

https://www.summitracing.com/parts/aaz-77-7730

 

Thanks for your information.
Do you think the prom is fine? I'm still not sure if this problem is caused by a bad ecm or a bad prom. I heard a prom doesn't go bad so easily, but what do you think?

 

Your right prom doesn’t got bad to often and if it looses data will probably get a code 41 or 51.
I think the ecm will even control fuel pump and do a code 12 without prom. Just a odd thing it won’t do the code 12 I think that built into the ecm
firmware not prom related

 

Thank you for your reply.
Yes, it's really odd the SES doesn't flash code 12. The ecm doesn't seem to recognize at all the connection between Pin A and B. I'll try a new ecm and let you know the result later.

 

Have you checked the ignition control module? Given these car's reputation I would think that to be more likely than the ECM. The symptoms line up - suddenly stopped running, cranks and cranks but won't fire.

 

Might also check injector pulse with a noid light . Icm like mentioned shorted injectors or ecm .
checking the basics fuel
pre, spark and injector pulse before you buy anything.

 

Thank you. Yes, the ignition control module failure can cause such symptoms, but that doesn't explain why an error code cannot be read including Code 12. Obviously the way the SES flashes is odd... The ecm doesn't recognize the connection between Pin A and Pin B (Nothing happens). Also, the main coolant fan starts to rotate right after the ignition is on, and stops when the SES flashes, and starts to rotate again when the SES goes out... The main coolant fan is controlled by the ecm, isn't it. If there were no such strange symptoms, I would also doubt ignition related parts.

 

Thank you. By the way, what do you mean by 'Icm like mentioned shorted injectors or ecm'?

 

Hate to say through parts at it but it sounds like a ecm replacement is a good choice at this point. Icm was mentioned post above mine just to check basics but the lack of code 12 seems to be ecm

 

Thank you guys, a new ecm has solved the problem!

I think the key was that any error code, including Code 12, could not be retrieved even with the proper prodecure. An odd symptom such that the SES lamp and the main coolant fan relay synchronize also helped me. It was not a simple "the engine won't run" symptom after all. I hope this will help someone in a similar situation.

 

Thanks for the update. Good info for future searches!

 

Bringing this post thread back as I am currently experiencing almost an identical issue but am still troubleshooting it.

Background
Car passed state inspection last April (2024) without issue and last drove the car a month later.
Go out this April (2025) with a fully charged battery. Turn the key and hear the fuel pump prime but the cooling fan also comes on but the A/C is set to vent. Turn the key to crank it and after a couple revs the engine fires up to 2,000-2,500 rpm for a second or so (sounding healthy) and then just dies. Continued to try around 20-30 times with the exact same result.

Keep in mind the SES light is illuminated as soon as the key is turned to prime the fuel pump, during cranking, and after it dies. I stuck wire in to the A/B pins of the ALDL and no change. The car just acted like no wire was present and would prime the fuel pump and refused to give any codes--displayed a solid SES light the whole time. No Code 12 or anything, just solid amber.

Troubleshooting
With some help I verified there was fuel at the rail, had 40 psi after priming. Added 2 gallons of fresh gas to the tank. Spark on the distributor, spark at the plugs. The car would start and run fine as long as he sprayed starting fluid through the MAF (sounding healthy too). Hitting the gas pedal did not help run the engine when it was running on starter fluid.

Verified cooling fan was running correctly by:
- Checked all fuses for continuity and they were good.
- Verified the cooling fan relay was good.
- Started car with different fan relay and still came on.
- Started car with Coolant Temperature Sensor unplugged and still came on (CTS replace Nov. 2019).
- Started car with High Pressure Switch on hard metal A/C line disconnected (A/C lost charge last year anyways; converted to R134a in 2018).

Things that I tried to get it to run include and tried starting car:
- Took off gas cap
- Started car with inline checker on distributor
- Started car with pressure checker on fuel rail
- Ran fine with start fluid being squirted through MAF
- Removed air snorkel and MAF from car and tried starting
- Tried starting with MAF removed and CTS unplugged
- Tried starting with MAF removed and A/C High Pressure Switch disconnected

Gas Tank, fuel sending unit, fuel pump, fuel filter, and spark plugs replaced in winter 2018.
This is a stock 305 TPI Motor in 1986 Camaro. Has headers and high flow exhaust with heated O2 sensor and all smog equipment is in place.

Based on how I received the Camaro, I doubt the computer has ever been touched. As the cooling fan is grounded by the ECM to turn on and the ALDL refuses to give codes, I believe my friend is right that the ECM has kicked the bucket. Anyone feel that is the case?

 

Sounds likely, might be worth seeing if you can get it open and look for a charred connection or some oxidation or something.