Well I should have known that all my hard work would lead to more hard work. Car is an 89 Corvette and I'm swapping from the 165 ECM. I built the adapter and used a new 90 Vette memcal. Turned the key and fule pump ran. Good sign. Cranked it over and it took a while to fire and then only in limp home mode. Threw in the old 165 and it ran good. Put the 7730 back in and same thing. I inspected the adapter and found a suspicious piece of solder that looked like it may have crossed two terminals. I threw the adapter over the hill and repinned the my ECM wires directly to the 7730 connectors. I figured this would do the trick. Same thing. Here is the wierd part. If I ground terminals A and B on the ALDL, the SES light stays steady. I know its in diagostic mode because the service ride select light flashs it's code 12. The ECM will show no codes and the Diacom will not link (I suspect my cable is bad anyway). As soon as you turn the key the fan comes on so its going directly to limp home mode.

How do I know if my ECM is bad? I'm hoping that's all it is. I bought it on Ebay as a working ECM. I'm thinking that I either fried it due to a shorted wire in my adapter or the ECM was bad to begin with.

Looking for any guidance.

Jason

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89 Six Speed FX3 coupe
More Performance 396cid specs:
Callies 4340 crank 3.875 stroke
Lunati Pro-Mod 5.85" rods
SRP Pistons 14cc dish
Comp Cams Custom cam 550 lift 220/229 duration
10.8:1 compression
AFR 195 competition ported heads
Miniram and TPIS 1 3/4" headers
Speed Density conversion in process

 

Which pins were shorted..

 

I didn't think at the time to make a note of which pins might have been shorted. I'm not even sure if they were or not. I inspected the adapter very close for any solder that may have crossed terninals. Then after I was satisfied, I applied hot glue to the casing. When I was removing the hot glue with my old solder iron, I may have melted some solder and crossed the terminals then. Is a steady SES light in diagnostic mode indicative of a fried ECM?

Jason

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89 Six Speed FX3 coupe
More Performance 396cid specs:
Callies 4340 crank 3.875 stroke
Lunati Pro-Mod 5.85" rods
SRP Pistons 14cc dish
Comp Cams Custom cam 550 lift 220/229 duration
10.8:1 compression
AFR 195 competition ported heads
Miniram and TPIS 1 3/4" headers
Speed Density conversion in process

 

You didn't do anything to the memcal? You left it stock correct?
If you can snag another computer i would try that first. And if its not the computer you will atleast have an extra one.
I would double check all of your wiring, it could be a very simple problem, like a backwards ground or something.


Brendan

 

Its a 90 vette memcal with the injector constant set at 33 for my 30 pound injectors.

Jason

 

Ok, but i mean, did you actually desolder the prom from it? If so that could be the entire problem. Loose connections are a PAIN!
You may think everything is ok but it probly isn't.

 

Oh I see what you mean. I removed the stock chip and soldered in a 29C256 flash prom. Visually all the connections look good.

Jason

 

I'm willing to bet that is your problem then, i have a flash prom in my SD computer and it works great. But i would go over your soldering connections. ohm across each pin, and then do some cross ohms to check for bridged connections. Then once everything looks ok you should give it another try.

 

Lierch is dead-on about the EEPROM most likely being the culprit. Solder fillets may look good, and still not be up to par. As clean as the EEPROM pins may look, and as nice as the welds seem, it's very difficult for an amature solderer to make good solder connections on something as tricky as a PROM-to-MEMCAL solder job.

I shouldn't say amature, because it's even difficult for someone with years of experience in soldering.

Like Lierch said, check your joints for continuity, and also check for continuity between pins along side of eachother. Continuity checks are important for ANY solder joints, any crimps, or any other wire connections for that matter. You would be suprised how easy it is to solder an item as an "open", and still have it looking good.

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86 Trans Am WS6 Black with tinted windows, shaved door handles
ZZ4, Mini-ram, true duals, LT4 HotCam, AFR 195 heads.
***Too many other mods to mention***

"In the future, cities will become deserts,
roads will become battlefields, and the hope of mankind
will appear as a stranger" The Road Warrior