1985 ECM Repair???
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1985 ECM Repair???
I took my ECM out my 1985 coupe because i cant read my codes for sum reason, so i was wondering if there is any place i can send it in to get it tested to see if it is operating properly.
Pro
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From: Lubbock for now, headed for Oklahoma
I would be checking your connections at the ALDL first. There are all kinds of reasons why you may not be able to read the codes. What is the car not doing or doing that made you need the codes in the first place?
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From: Lubbock for now, headed for Oklahoma
Put a vacuum gauge on it, and see if the vacuum starts dropping from the time of startup.
Last edited by BluRay; Dec 26, 2008 at 02:29 PM.
Pro
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From: Lubbock for now, headed for Oklahoma
Okay well this isn't even a stretch really. When you turn the key on does the engine light come on for two seconds and then go off after the codes have been cleared?
The fact that you cannot get the code cycle may be a real indicator of the issue. Take an ohmmeter and check the signal ground at the ALDL it should have very little resistance.
Did you ever get to put a vacuum gauge on it? A steady drop in vacuum before and as it starts to stall is a good indicator that the exhaust has a clog.
Do you have a hand operated vacuum pump?
Last edited by BluRay; Dec 27, 2008 at 12:02 AM.
Le Mans Master
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From: Tampa Florida
Your car runing for 10 seconds then dieing sounds like a fuel related issue to me. Most fuel problems on these C4 cars will not send a "trouble code". Pick up a fuel rail pressure gage...use it and see what is going on there.
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Also When i looked under the dash by all the wiring there was a black wire hanging, i looked on all the plugs and found 1 that has one missing but i dnt see where the other end of the wire goes.
With the wire being black i assume it is a ground???
With the wire being black i assume it is a ground???
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Ive Taken it to the Local repair man and he has a scanner and he said his machine couldnt read the computer for sum reason.
I also Think it sounds fuel related but i need to start wit the problem with the codes not reading first because if there is sumtin wrong wit it The ECM it could send all Sorts of Faulty signals
I also Think it sounds fuel related but i need to start wit the problem with the codes not reading first because if there is sumtin wrong wit it The ECM it could send all Sorts of Faulty signals
Le Mans Master
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From: Myrtle Beach SC
St. Jude Donor '05-'06
You need to start by getting a FSM if you want to figure out why it is not reading and what that wire goes to. I suspect it is a ground.You might try finding a different ground (pin "A" of the ALDL) and connecting it to pin"B" to read your codes.Quit guessing if you have fuel pressure as you said it is not fuel related.
http://www.corvettebuyers.com/c4vettes/ecm.htm
http://www.carcraft.com/techfaq/116_...t/sensors.html
http://www.corvetteactioncenter.com/...cm-repair.html
http://www.corvettebuyers.com/c4vettes/ecm.htm
http://www.carcraft.com/techfaq/116_...t/sensors.html
http://www.corvetteactioncenter.com/...cm-repair.html
Safety Car
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From: Salem NH
What are you doing to get them? There are several component tests you need to do before sending that thing off. Starting with the MAP sensor. I have seen them cause this due to diaphram leaking. I would also take a serious look at your exhaust. A clogged catalytic converter or muffler will do this as well.
Put a vacuum gauge on it, and see if the vacuum starts dropping from the time of startup.
Put a vacuum gauge on it, and see if the vacuum starts dropping from the time of startup.
-- Joe
Safety Car
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From: Salem NH
The '85 was a one off year. The ECM was only used in that year. Most guys I know repin them to later style MAF or MAP ecm's. But it worked in 1985, so it should still work now. They are fairly easy to troubleshoot - it's just, when they go bad it's cheaper to repin to a newer faster ECM.
-- Joe
Pro
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From: Lubbock for now, headed for Oklahoma
Safety Car
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From: Salem NH
On the CC Carb setups they had a baro sensor, but not on the '85 TPI setups.
Looking back I cannot confirm there is any BARO on an '870. Keep in mind I've worked on Fbody's not Corvettes. There is a minor difference between the '870 on a vette and an fbody when doing the repin but I don't recall a baro or map sensor.
Of course I can't find the last thread I recall on the difference.
--Joe
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From: Lubbock for now, headed for Oklahoma
Not as if it is the best info but the AutoZone repair info site shows them having one, but that doesn't say what inputs they provided or under what conditions. I would bet they were more just for start up BARO and WOT BARO.
Would be interesting to know.
Would be interesting to know.