Electrical Gremlins or coincedence?
Thread Starter
Le Mans Master
Joined: Dec 2003
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From: Van Steel Corvettes
St. Jude Donor '12-'13
Electrical Gremlins or coincedence?
Ok, so a few months ago I drain the battery. I jump it, it's fine. But then the Auto A/C and Auto Fans no longer work. I have to manually control everything but it still blows cold...ICE COLD. And now that it's winter I find out the Heater isn't working either, just blows one temp at whatever speed I set. And on top of that, my LTPWS will also come on randomly and everynow and then say I have a low tire when I do not. I had the sensors checked out and three of the four where showing errors.
Could all this be related to something shorting out when I jumped the battery? I also found out, when the car was new a module of some sort had to be replaced (was in the shop for 3 out of the first 4 months after it was purchased) for the A/C. Going to bring it to the mechanic next tuesday, but I'd like to have an area for him to pinpoint than just shoot and miss...
Some may have read a simliar post a while back. I though it was corrected, so I'm not have to see if anyone has any further input. Thanks.
Could all this be related to something shorting out when I jumped the battery? I also found out, when the car was new a module of some sort had to be replaced (was in the shop for 3 out of the first 4 months after it was purchased) for the A/C. Going to bring it to the mechanic next tuesday, but I'd like to have an area for him to pinpoint than just shoot and miss...
Some may have read a simliar post a while back. I though it was corrected, so I'm not have to see if anyone has any further input. Thanks.
Pro
Joined: Aug 2004
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Jumping a totally dead battery should be a last resort. It can produce some nasty voltage and current surges. Start checking fuses. Most of what you describe is controlled by the CCM. If you have an FSM, it is in section 8D.
Last edited by lefoy84; Dec 7, 2006 at 04:25 PM.
Le Mans Master
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From: San Diego, Ca
Maybe, maybe not. Assuming it's electronic a/c, some funky things can happen when it starts to lose it's memory. I would simply disconnect and reconnect the battery so that whatever it had in it is definitely returned to a blank page. Afterwards, it may take a few seconds to a few minutes for it's (the a/c) Processor - the Programmer - to learn a couple of things, but after that it might just start working again.
Team Owner
Joined: Mar 2001
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From: Cincinnati, Oh USA
If you connected with the correct polarity during your jump start, you should not harm any of your electrical equipment. Voltage spikes occur with every starting when the starter solenoid disconnects the starter motor. Your electrical problems are coincidental with the jump start.
Former Vendor
Joined: May 2006
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Originally Posted by jfb
If you connected with the correct polarity during your jump start, you should not harm any of your electrical equipment. Voltage spikes occur with every starting when the starter solenoid disconnects the starter motor. Your electrical problems are coincidental with the jump start.
Thread Starter
Le Mans Master
Joined: Dec 2003
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From: Van Steel Corvettes
St. Jude Donor '12-'13
Originally Posted by SunCr
I would simply disconnect and reconnect the battery so that whatever it had in it is definitely returned to a blank page. Afterwards, it may take a few seconds to a few minutes for it's (the a/c) Processor - the Programmer - to learn a couple of things, but after that it might just start working again.
Le Mans Master
Joined: Dec 2000
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From: San Diego, Ca
Blinking LED usually indicates a trouble code. Retrieval procedure is here: https://www.corvetteforum.com/techti...=193&TopicID=2
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Thread Starter
Le Mans Master
Joined: Dec 2003
Posts: 5,768
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From: Van Steel Corvettes
St. Jude Donor '12-'13
Originally Posted by SunCr
Blinking LED usually indicates a trouble code. Retrieval procedure is here: https://www.corvetteforum.com/techti...=193&TopicID=2
Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
Originally Posted by KEN W ANDERSON
This is bad advice, as the car's computers are all in sleep mode yet still are drawing current during off conditions. Jump starting a 82 up Corvette is asking for trouble-you can damage many modules.
Former Vendor
Joined: May 2006
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Originally Posted by jfb
How is it bad advice? It doesn't make any difference what state any module or the ECM is in. If you connect a 12v battery to a 12v battery you will only get a jump in voltage to the good battery voltage. How will that hurt anything? There are large voltage spikes that occur when the starter solenoid turns off the current to the cranking starter motor, MUCH larger spikes than the 1 to 2 volts you get when you jump a charged battery to your discharged battery. Starter motors draw 100+ amps and are inductive, so when the starter current is interrupted the voltage spike/s will be V = L di/dt . How many times have you damaged any of your electronics in your car when you start it? I never have. Now if you connect the jumper battery with reversed polarity, THEN you can do some major damage!
Team Owner
Joined: Mar 2001
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From: Cincinnati, Oh USA
Originally Posted by KEN W ANDERSON
If you jump start a dead battery then you get a voltage spike to everything in the system that is always "on". You should disconnect a dead battery, charge it, then reconnect + first - second. I suggest you read a shop manual, the electrical section specifically, from GM. Car computers are very sensitive to errant voltage surges and are easily damaged-read the forums.
You clearly are not aware that the ECM, radio, and the cluster has a protective MOV (metal oxide varistor) on their 12v inputs to protect them from voltage transients!!!!!!!!!!!!!!!!!!!!!!!!!!!
Last edited by jfb; Dec 9, 2006 at 03:50 PM.
Former Vendor
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Originally Posted by jfb
I have a shop manual from GM for my 87 Corvette and it does not prohibit jump starting! Just what do you think happens when you connect a charged battery back up to your battery cables? The exact same voltage transient occurs as connecting a charged battery to assist your discharged battery, namely a jump from 0 to +12v which won't hurt any electrical equipment in your car! Connect an oscilloscope across your battery terminals and watch the voltage spikes that occur when you stop cranking the engine!!!!!!!!!! And guess what, all car manufacturers know about these nasty transients and design all of their electrical equipment to safely deal with it. You are not thinking clearly when you advise charging your battery and then reconnecting it if you think jumping your discharged battery with a charged one is harmful.
You clearly are not aware that the ECM, radio, and the cluster has a protective MOV (metal oxide varistor) on their 12v inputs to protect them from voltage transients!!!!!!!!!!!!!!!!!!!!!!!!!!!
You clearly are not aware that the ECM, radio, and the cluster has a protective MOV (metal oxide varistor) on their 12v inputs to protect them from voltage transients!!!!!!!!!!!!!!!!!!!!!!!!!!!
Race Director
Joined: Jan 2006
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From: CA
Well,it's poring rain right now,and I don't want to go out to the shop to check.But I think I've read the the owners manual that came with the car,not the FSM mind you,I'll check that too.But I don't think it said anything about not being able to jumpstart from another car battery.
From memory,it just says to make sure of the polarity when hooking up jumper cables.And be aware of hydrogen gas given off by the batteries.You know,the basic CYA from chevy.
I wouldn't think the owners manual would tell you to do somthing that would harm the electronics.Mine's an 86 though,maybe later models are more prone to damage.Tomarrow I'm going to check,both.
From memory,it just says to make sure of the polarity when hooking up jumper cables.And be aware of hydrogen gas given off by the batteries.You know,the basic CYA from chevy.
I wouldn't think the owners manual would tell you to do somthing that would harm the electronics.Mine's an 86 though,maybe later models are more prone to damage.Tomarrow I'm going to check,both.
Last edited by GIMMESOME; Dec 9, 2006 at 10:07 PM.
Le Mans Master
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From: San Diego, Ca
Way over my head and I'm dangerous with a soldering iron, but there is nothing in the Service Manual or Owner's Manual expressing this warning - for any computer controlled vehicle I've owned (Ford, Toyota, Chevy, Pontiac & VW) I was at Borders this PM, so out of curiosity, I did peruse Auto Repair For Dummies. It essentially said that it's ok to jump start unless there is a specific warning stuck somewhere and if the last annual report I looked at for Auto Club was accurate, they're still making a ton of Bucks doing this without any reserve set aside for fried ECMs or damaged electrical components. Since this involves a/c, I would be more inclined to make sure that the diode in the a/c clutch circuit is connected and operational. Otherwise, all the a/c courses teach you that the collapsing magnetic field can overjuice whatever controls the clutch and for this Year it's the ECM (though that's simply a ground driven relay). Still I'd check it - especially if the A/C Programmer is dead or being replaced with any frequency.
Burning Brakes
Joined: Mar 2006
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From: Dayton Ohio
I have a shop manual from GM for my 87 Corvette and it does not prohibit jump starting! Just what do you think happens when you connect a charged battery back up to your battery cables? The exact same voltage transient occurs as connecting a charged battery to assist your discharged battery, namely a jump from 0 to +12v which won't hurt any electrical equipment in your car! Connect an oscilloscope across your battery terminals and watch the voltage spikes that occur when you stop cranking the engine!!!!!!!!!! And guess what, all car manufacturers know about these nasty transients and design all of their electrical equipment to safely deal with it. You are not thinking clearly when you advise charging your battery and then reconnecting it if you think jumping your discharged battery with a charged one is harmful.
You clearly are not aware that the ECM, radio, and the cluster has a protective MOV (metal oxide varistor) on their 12v inputs to protect them from voltage transients!!!!!!!!!!!!!!!!!!!!!!!!!!!
You clearly are not aware that the ECM, radio, and the cluster has a protective MOV (metal oxide varistor) on their 12v inputs to protect them from voltage transients!!!!!!!!!!!!!!!!!!!!!!!!!!!
Not only is the above correct but realize that an automobile's electrical system is about as "noisy" as it gets. This is usually bad for sensitive transistor based electronics. To give you an idea, many ECM microprocessors reset several times a second to prevent corrupt data handling.
There is nothing wrong with jump starting a good battery, dead battery or in between.
Now back to A/C and heating........
Have you run codes on your CCM? How about the A/C control unit yet? Both the CCM and A/C programmer are a challenge to remove and replace. Your problems will most likely lie in one of them because chances are that the wiring is good. You really need to see if you are getting error codes from them. If you have blinking lights on the A/C control head that means that there are codes in the A/C programmer.
Your A/C freon might need to be charged too. That will throw a code.
Team Owner
Joined: Mar 2001
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From: Cincinnati, Oh USA
Originally Posted by KEN W ANDERSON
This last statement is completely untrue for a GM car produced from 84-96
Race Director
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From: CA
I couldn't stand it anymore,braved the weather,went out to my shop and grabbed the owner's manual.
If the battery is dead,jumpstart the damn thing ,according to the manual,you wont kill your car.If your battery went dead in the first place,there must be a reason,find the problem and fix it.Be safe.
If the battery is dead,jumpstart the damn thing ,according to the manual,you wont kill your car.If your battery went dead in the first place,there must be a reason,find the problem and fix it.Be safe.
Last edited by GIMMESOME; Dec 10, 2006 at 02:21 AM.
Le Mans Master
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From: Magnolia Mississippi
St. Jude '03-'04-'05-'06-'07
Originally Posted by KEN W ANDERSON
This last statement is completely untrue for a GM car produced from 84-96
Former Vendor
Joined: May 2006
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Originally Posted by jfb
You don't know what you are talking about. Go to www.batee.com . He has a schematic there for an 89 cluster and you can see the MOV across the 12v line. The MOV is located on the piggyback power supply board. Call Delphi and ask for a schematic for any vette radio 84-96 and see the zener diode to ground on the 12v line, they do the same thing as a MOV.