93 C1500 - Refurbished ECM or EPROM Took a Dump - Need Advice

[LA2SD]

1993 Chevy Silverado 5.7L V8 w/ TBI and 4L80E - LA2SD's '93 RCSB

So, I was cruising the other night when my truck died without warning. I went through it the best I could, and tried restarting it, but no luck. I had plenty of gas, but the truck felt like it wasn't getting any fuel.

Towed it home, and re-checked all of my basic connections (e.g. alternator, battery, plug wires, distributor cap, spark, fuses, etc.), double checked to make sure I had fuel, and everything looked fine.

So I moved on to checking DTCs (diagnostic trouble codes) for any possible issues, and the MIL (malfunction indicator lamp) would not flash DTC 12, which is supposed to indicate that the truck's diagnostic system is functioning properly.

According to the shop manual, if DTC 12 doesn't flash, there's either 1) a short 2) an open, or 3) a defective ECM/PROM (engine control module).

I followed the flow chart, which led me to the ECM. The problem is that it could be either the ECM or the PROM that is defective. And based on the flow chart, I won't know which until I replace the ECM.

The ECM was replaced once before by the PO, and I don't want to replace the ECM again if it's actually the PROM. If it's the PROM, I can replace it with a ZIF socket and flash memory.

Before posting up, I read through Putting A Chip In A TBI Truck, which had some great advice on doing just that.

My questions are:

1. Is there a way to test the ECM and PROM separately - without having to buy a refurbished ECM?

2. How does the factory "refurbish" an ECM? Do they simply write a new BIN file to the PROM? Or is it more of an electronics issue, where they use an oscilloscope and specialized knowledge to test for faulty components?

If all they're doing when "refurbishing" an ECM is to write a new BIN file, I could use tuning software to write a new BIN file, and "refurbish" it myself.

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[ima93chevyguy]

A refurbished ECM does not come with a PROM.
You have to use yours.

 

[LA2SD]

^Ah, okay...I guess I can try modding my old ECM, since EEPROMs and ZIF sockets are relatively cheap, and if that doesn't work, get a refurbished ECM. I wonder what it is that wears out...

 

[PlayingWithTBI]

The old EPROMs will lose their memory after so many years. I went with the ZIF socket and 27SF512 EEPROM flash chips. Bought an ALDL cable, Moates Burn2, and downloaded TunerPro RT for my 88 C1500. Now I can data log and flash my own. You can read your OE chip with the Burn2 but can't burn them. You can also look up your bin file on Gearhead EFI

http://aldlcable.com/aldl.asp

http://www.moates.net/burn2-chip-programmer-p-197.html?cPath=94

http://www.tunerpro.net/

http://www.gearhead-efi.com/gearhead-efi/

 

[ima93chevyguy]

^Ah, okay...I guess I can try modding my old ECM, since EEPROMs and RIF sockets are relatively cheap, and if that doesn't work, get a refurbished ECM. I wonder what it is that wears out...

Whatever it was that affected my shift points was not in the PROM because I tried a remanned computer and used my PROM and that fixed the shifting.

 

[Supercharged111]

Is it out of the question to just grab both from a junkyard?

 

[LA2SD]

The old EPROMs will lose their memory after so many years. I went with the ZIF socket and 27SF512 EEPROM flash chips. Bought an ALDL cable, Moates Burn2, and downloaded TunerPro RT for my 88 C1500. Now I can data log and flash my own. You can read your OE chip with the Burn2 but can't burn them. You can also look up your bin file on Gearhead EFI

http://aldlcable.com/aldl.asp

http://www.moates.net/burn2-chip-programmer-p-197.html?cPath=94

http://www.tunerpro.net/

http://www.gearhead-efi.com/gearhead-efi/

Awesome, thanks! I actually came across one of your posts in the TBI thread and it was really helpful.

 

[LA2SD]

Whatever it was that affected my shift points was not in the PROM because I tried a remanned computer and used my PROM and that fixed the shifting.

I'm hoping it's the PROM, and not the motherboard, but you might be right. I just don't wanna buy a new ECM if my old one's good. I should probably find out what the return policy is on an ECM. If the outfit takes it back without any restocking fees, then I don't see a problem.

 

[LA2SD]

Is it out of the question to just grab both from a junkyard?

The only problem with ECMs from the junkyard is that you don't know what you're getting until it's plugged in. But that could be an option.

 

[Supercharged111]

The only problem with ECMs from the junkyard is that you don't know what you're getting until it's plugged in. But that could be an option.

True as that is, they generally give a 30 day warranty and ECMs going bad is more out of the ordinary so I don't see it being that big of a crapshoot. Getting the right chip may be though.