Computer Blues
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Joined: Sep 2013
Posts: 64
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From: Clover SC
Computer Blues
1982 Standard Vette, 112,000 miles, 2 owner, all original except for the xcel coil and hypertech chip.
Can't for the life of me figure out this issue:
The computer just dies! This is the 3rd time in about 6 months. Keep in mind that in that 6 months, I've only driven the car maybe 10 times, so this is an issue!
The car drives fine and then I park it. Come out to it the next day, it cranks and cranks, but won't start. The CEL is out. It won't come on with the ignition or anything. If I send off for a new computer, it will work fine for a while, and then the same thing; no start.
At first, I thought it was the battery, because I drive it so little, the battery would be flat, so I'd charge it, and then it would crank and crank, but no fire.
Put in a new computer, drives great!
Wow, is this a teaser?
Can't for the life of me figure out this issue:
The computer just dies! This is the 3rd time in about 6 months. Keep in mind that in that 6 months, I've only driven the car maybe 10 times, so this is an issue!
The car drives fine and then I park it. Come out to it the next day, it cranks and cranks, but won't start. The CEL is out. It won't come on with the ignition or anything. If I send off for a new computer, it will work fine for a while, and then the same thing; no start.
At first, I thought it was the battery, because I drive it so little, the battery would be flat, so I'd charge it, and then it would crank and crank, but no fire.
Put in a new computer, drives great!
Wow, is this a teaser?
Last edited by DickieB; Jun 8, 2016 at 03:28 PM.
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Advanced
Joined: Sep 2013
Posts: 64
Likes: 2
From: Clover SC
Burning Brakes
Joined: Apr 2008
Posts: 1,222
Likes: 93
From: shelbyville West Michigan
couple things to check. first is the tap test. when the computer gets old it gets cold solder joints. start the car, with the computer out, cover off, and tap with your finger on the chip, and other places where things plug in. if it stalls, you found it. sounds low tech but sometimes that's what it takes. I fixed a few cars that way when the dealer couldn't even find the intermittent issue. next use a hair dryer and see if it stalls when it heats up. be careful and don't cook the board, just heat it up and see if it kills.
then trace the power wire to the ECM. not sure on the vette, but early CCC and OBD1 systems on lots of GM's had a dedicated 12v power wire direct to the battery as part of the positive cable. it is thin, and orange IIRC, and they get corroded and lose power, especially if someone changed the cables out. when there is no power to the ECM, you have no engine light, and no control of the injectors. this was common on the old chevy celebrity's, cavaliers, etc. from early to mid 80's, so get a wire diagram and find where the main 12v power feeds from and trace it. it may or may not go direct to the battery, maybe on vette's it's at the starter or the other main bus...
hope that helps.
then trace the power wire to the ECM. not sure on the vette, but early CCC and OBD1 systems on lots of GM's had a dedicated 12v power wire direct to the battery as part of the positive cable. it is thin, and orange IIRC, and they get corroded and lose power, especially if someone changed the cables out. when there is no power to the ECM, you have no engine light, and no control of the injectors. this was common on the old chevy celebrity's, cavaliers, etc. from early to mid 80's, so get a wire diagram and find where the main 12v power feeds from and trace it. it may or may not go direct to the battery, maybe on vette's it's at the starter or the other main bus...
hope that helps.
Thread Starter
Advanced
Joined: Sep 2013
Posts: 64
Likes: 2
From: Clover SC
Thanks for your replies gentlemen.
I put the original chip in (can you believe it was still in my bedside table drawer after all these years? maybe I should clean that drawer out, maybe not!) anyway, it still didn't start.
I can check for power on the wire if I knew exactly which one it is. Is there more than one orange wire going to the ECM?
Keep in mind that this is a newly refreshed ECM from Cardone.
I put the original chip in (can you believe it was still in my bedside table drawer after all these years? maybe I should clean that drawer out, maybe not!) anyway, it still didn't start.
I can check for power on the wire if I knew exactly which one it is. Is there more than one orange wire going to the ECM?
Keep in mind that this is a newly refreshed ECM from Cardone.
Burning Brakes
Joined: Apr 2008
Posts: 1,222
Likes: 93
From: shelbyville West Michigan
you may want to invest in a FSM (factory service manual) for that vehicle, I know they are not cheap, but I was chasing a computer issue on my '95 years ago and it was well worth the money. it will have the wiring for each component spelled out with the proper test procedures to step by step through the ECM connectors, what voltages and grounds you should see, etc. normally I'd say ask Wilcox or someone else for the free wiring diagrams but you're gonna need some diagnostic tests me thinks...
I attached a pinout scan I found online from 82 crossfire you can see the 5v reference, battery, various grounds etc. hope it helps.
I attached a pinout scan I found online from 82 crossfire you can see the 5v reference, battery, various grounds etc. hope it helps.
Safety Car
Joined: Nov 2005
Posts: 3,532
Likes: 1,185
From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
1982 Standard Vette, 112,000 miles, 2 owner, all original except for the xcel coil and hypertech chip.
Can't for the life of me figure out this issue:
The computer just dies! This is the 3rd time in about 6 months. Keep in mind that in that 6 months, I've only driven the car maybe 10 times, so this is an issue!
The car drives fine and then I park it. Come out to it the next day, it cranks and cranks, but won't start. The CEL is out. It won't come on with the ignition or anything. If I send off for a new computer, it will work fine for a while, and then the same thing; no start.
At first, I thought it was the battery, because I drive it so little, the battery would be flat, so I'd charge it, and then it would crank and crank, but no fire.
Put in a new computer, drives great!
Wow, is this a teaser?
Can't for the life of me figure out this issue:
The computer just dies! This is the 3rd time in about 6 months. Keep in mind that in that 6 months, I've only driven the car maybe 10 times, so this is an issue!
The car drives fine and then I park it. Come out to it the next day, it cranks and cranks, but won't start. The CEL is out. It won't come on with the ignition or anything. If I send off for a new computer, it will work fine for a while, and then the same thing; no start.
At first, I thought it was the battery, because I drive it so little, the battery would be flat, so I'd charge it, and then it would crank and crank, but no fire.
Put in a new computer, drives great!
Wow, is this a teaser?
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Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
The fuse for your computer, fuel pump and oil pressure switch is the fuse that is located in your battery box...located on right rear side of your battery box.
Memory serves me correctly..it is a 20 amp.
If you have problems with this computer..there is another source that I use. PM me if interested. And if your factory prom is bad....this same company also offers facotry proms also.
DUB
Memory serves me correctly..it is a 20 amp.
If you have problems with this computer..there is another source that I use. PM me if interested. And if your factory prom is bad....this same company also offers facotry proms also.
DUB
Last edited by DUB; Jul 11, 2016 at 05:37 PM.
Racer
Joined: Jan 2016
Posts: 290
Likes: 78
i doubt you have a prom or are getting a rash of bad ecm's. 3 ecm's in 6 months tells me you either have a bad sensor or ecm controlled device. ANY sensor or controlled device with high resistance in the circuit will cause a high current draw through the ecm. high draw results in high heat and failure of the circuit board. before installing a new ecm again you need a GOOD powertrain control module wiring diagram and test every sensor and controlled devices circuit at the ecm's connectors. you need to make sure there isn't high resistance or shorts to power or ground. you need to make sure all grounds are good. poor grounds=high resistance. also need to make sure the ecm's grounds are good. long time ago iac motors and lock-up solenoids were notorious ecm killers. it's time consuming but you have to find out what's killing the ecm's. good luck.