C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

1993 issue

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Old Jul 7, 2011 | 01:55 PM
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Default 1993 issue

hello all....I've been out of the vette game for a few years now(sold my C3 10 years ago).I am here with the hopes I could get some help for an ole computer illiterate Vet im friends with. He has a 93 that had no start/stall after start issues. I researched the most common issues/symptoms and after checking several things, I came to the conclusion it was the ICM or a computer issue. We gambled, and replaced the ICM and it wasn't it. We gave up and he actually took it to a dealership. First they said it was a security issue, and also they replaced the distributor cap. Now he just got a call saying it needs a new computer.....for $3,000!...help him out please...that would be the ECM by the passenger feet under dash correct?.....also..where is a good place as far as getting a new one/refurb'd one....thanks...
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Old Jul 7, 2011 | 02:16 PM
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Ouch!
It is probably not the computer. A new computer is impossible to find.
Anything he gets will be rebuilt. And I can't beleive they are charging $3000 to change a $400 part (list price) that takes 10 min to replace.
The ECM is in the engine compartment right out where you can see it. Takes removing 3 nuts and 3 wiring connectors.

Sounds like the dealer does not have a competent Vette Mechanic. They are going to bend him over with changing parts.
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Old Jul 7, 2011 | 02:26 PM
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Welcome to the forum. If you had a more detailed description of the problem there are many on here that will help you get running without arbitrarily changing parts. Some of the sponsors here have refurbished ECM's and the price should be around $250. With that being said, the ECM's are typically very reliable units and although anything electrical can fail, they rarely do.

Many dealerships would have you believe that all the parts they changed were bad when, in fact, only one part was faulty. As I mentioned, describe your problem more fully and some of the excellent troubleshooters on here will be more than glad to help. This is going to be dependent on some of your skills but the answer will come. Have a great day and good luck.
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Old Jul 7, 2011 | 02:44 PM
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thanks so far....
it all started that the car would start up fine...then when he parked it it wouldnt restart or it would restart and you would work the throttle and and it would still die...the stability control light would stay lit..

used a paper clip to check the codes..nothing..
checked the battery..fine
checked the tps using ether...nothing.. so ruled it out
all the while if it sat for a long period of time, it would restart..
replaced the ICM and disconnected the battery..started, took her for a drive...and lights would come on intermittently..security..stability control, check engine, took her back to his house, shut her down, tried to immediately restart, nothing....
no codes as far as i know...

bear with me as i am a "working on a c4 novice"...what computer is by the passenger footwell light, and what is right near the battery?..



i have a 46 cj2a which is much easier to fix but my FIL just bought a beautiful small block 70 vette so i forsee another in my future...still miss my 406 76 vette
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Old Jul 7, 2011 | 02:59 PM
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Do you have a no-start situation or no-crank?
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Old Jul 7, 2011 | 03:08 PM
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no start.....she was cranking all day..
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Old Jul 7, 2011 | 03:12 PM
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And ether didn't make it fire so it's a spark issue. Is that your thought?
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Old Jul 7, 2011 | 03:12 PM
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When the car will not start, do you have spark? Coils have been known to short internally when warmed up.
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Old Jul 7, 2011 | 03:21 PM
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i'll have to get back to you on that...i assumed that with no/intermittent spark it would have thrown a code...i currently assume that the dealer would have checked the spark (i last tinkered with it 1.5 weeks ago,then went on vacation, dealer just called today)
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Old Jul 7, 2011 | 03:26 PM
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Another approach could be to check grounds, also battery terminals for good connections. An iffy ground could cause the other intermittent symptoms
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Old Jul 7, 2011 | 03:28 PM
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will check grounds...batt terminals/wire ends were cleaned when i disconnected the battery

also 1963ss....the ether was the tps check i read online..that if the tps goes/is going it can tell the ecm the engine is flooded and kill the spark..the ether "overides" that...supposedly..

side info...i forgot to mention...you can hear the fuel pump come on/hum...and the schraeder valve has pressure/shoots out fuel...

what is the difference between the ccm and the ecm?

thanks so much for the help..
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Old Jul 7, 2011 | 03:38 PM
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ECM- electronic control module

CCM- central control module

Engine is controlled by the ecm with input from various sensors. This is the unit that's under the hood at the firewall in front of the driver.
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Old Jul 7, 2011 | 03:47 PM
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Here is a current listing for a 93 ECM on ebay, the seller indicates he has three and as you can see the price is far less than $3K

http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT

I would have the car towed to a vette specialty shop to get a second opinion. Another option is to tell us your location, perhaps a local forum member can help.
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Old Jul 7, 2011 | 03:52 PM
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If you decide that the ecm is at fault, here are two websites for rebuilding them. I have good experience with the first one, no info on the second.

www.autoecms.com

www.autocomputersystems.com

IIRC, one or both of these co's will check your ecm for a nominal fee before you buy a replacement.
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