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Topic: ECM Bad? 82 wiring guru needed

in Forum: C3 Electrical


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ECM Bad? 82 wiring guru needed (1/10)
 3/19/11 9:52pm
Shawnee2
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Cherryville, NC - USA

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82 Collector


Joined: 1/10/2011
Posts: 84

Since I did not get too far with my battery drain post I thought I would list it a little differently this time.
 
My battery is draining in less than a week.  Here is what I have determined so far:  with a DVM connected between the negative side of the battery and the cable I am getting about 0.5 amp draw.  Obviously way to high.  All testing is being done with the ignition switch in the off position.

What I have tried so far:  I think my ECM is causing the excessive drain.  There are 2 connectors on the ECM.  When I disconnect the smaller one, no change in amp draw.  When I disconnect the larger one amp draw goes away.  This is the one that powers the ECM from the battery.

I disconnected everything that the wires from the larger connector goes to through either the up-line connector (C455) for most of the wires, the oil pressure sender, fuel pump relay, disconnecting the TCC Control, E cell timer module, MAP Sensor, TPS, courtesy timer and all fuses.  Still have 0.5 amps.  I checked for voltage on the C455 connector after it was unpluged and I am getting some voltage on a couple wires which I do not think I should have.

Can my ECM be bad and causing the amp draw? 

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ECM Bad? 82 wiring guru needed (2/10)
 3/20/11 11:02am
rraider1
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Woodland, WA - USA

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1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion


Joined: 10/14/2003
Posts: 1165

It is possible here is a service buliten I found
 
ECM Bad? 82 wiring guru needed (3/10)
 3/21/11 7:58am
crossfire1982
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Cramerton, NC - USA

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black 1982 coupe slate gray interior, 350 crossfire, 1985 fuel pump, Steeroids R&P conversion


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Wish I could help on this one Jeff, but an electricl guru Im certainly NOT...see there, I can't even spell it.
ECM Bad? 82 wiring guru needed (4/10)
 3/21/11 1:47pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


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The TSB that Bob provided will give you testing procedure and thus the final answer, as far as whether or not the ECM is the root cause. Hope so, anyway...

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ECM Bad? 82 wiring guru needed (5/10)
 3/21/11 8:09pm
Shawnee2
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Cherryville, NC - USA

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Plugged a remanufactured ECM I got from someone in today and my problem seemed to go away.  Only plugged the one connector in at this time but currently very little amp draw.  Will try to connect everything I removed back in later this week and see what happens.  I'll use the TSB as a starting point to measure the draw.  Hope I have it corrected as I'm at a loss as to where to go next if not.
 
Thanks for the help.
ECM Bad? 82 wiring guru needed (6/10)
 3/21/11 10:36pm
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Duncanville, TX - USA

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Fingers crossed! 

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Joel Adams
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ECM Bad? 82 wiring guru needed (7/10)
 3/21/11 10:39pm
dskopp
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Oak Creek, WI - USA

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1981 Great White Shark. Red Interior, 350/190hp. PS, PB (SS), A/C CC, T-Tops, Going to remain as Stock as possible. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vetts Car Club. 175,000 Original miles!!


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It could be a problem with either the ECM or the PROM !!
Dan


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ECM Bad? 82 wiring guru needed (8/10)
 3/22/11 6:46pm
Shawnee2
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Cherryville, NC - USA

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I have not tried to start or run the car since the switch.  I just pulled the ECM, switched the Prom and plugged the one connector back in to the new ECM to see if I had any draw.  Still have quite a few things to hook back up to verify this resolved the issue.  Did not consider the PROM.  I am assuming once I start the car everything will still be ok (no draw) and the PROM will recover all the information needed.  Anything special I need to do since I pulled and switched the PROM?

I'm not up to speed on the ECM side.
ECM Bad? 82 wiring guru needed (9/10)
 3/22/11 11:08pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

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The PROM(Programable Read Only Memory) simply contains the operational info/program for the system. No need to relearn anything on purpose, or do anything like that. The info is "burned" onto the PROM...it cannot be changed, or altered just by removing/replacing it...unless you bend some of the pins, or put it in the wrong way/backwards.....THEN you'll have a problem!
I've never seen/heard of a PROM causing a voltage drain...it's not really something that could do that, in itself. It's more likely some of the circuitry in the ECM, or a failed component that is causing the drain.
Still got me fingers crossed!


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Joel Adams
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ECM Bad? 82 wiring guru needed (10/10)
 3/25/11 10:59pm
dskopp
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Oak Creek, WI - USA

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1981 Great White Shark. Red Interior, 350/190hp. PS, PB (SS), A/C CC, T-Tops, Going to remain as Stock as possible. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vetts Car Club. 175,000 Original miles!!


Joined: 5/21/2008
Posts: 1958

Putting the PROM in the wrong way is a REAL problem.  You will insteantly burn the PROM !!  Trust me!  I did it !!!  There is a way to test the circuitry of the ECM.  I have a friend who worked at the AC Delco Plant, here in Oak Creek Wisconsin, that Engineered the ECM.  I will try to pick his brain!!

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