Welcome to the Corvette Forums at the Corvette Action Center!

Help! Parasitic Draw

ARKvette02

Well-known member
Joined
Mar 12, 2009
Messages
239
Location
Virginia/New Jersey (EXIT 91)
Corvette
2000
;helpJust bought a new battery and when I connected the terminals they sparked bad... I was concerned so tested...1.6 to 2.4 amp draw!!!! any ideas ??? i know normal is .30 ma but didn't know if it was just initial till computer booted... please help!!!
 
Just went back out to car...when I connect the battery I hear a relay, or something clicking by passenger side head lite..... is there is module or something down there???
 
That is a normal relay sound. You will get a couple of amps current flow until the BCM goes into sleep mode which can take several minutes. Some of what you saw was the hood light since I bet you didn't remove it.

In case you need it:

Here is some info for determining if you have a parasiticdrain. Let me know if I need to clarify anything of if I can help in any way.

Suggest you remove the hood light bulb first so it does notprovide a drain.

For measuring battery drain I would hook up an ammeter tothe negative side of the battery by removing the negative cable and measurebetween the cable and the negative battery post.

When you connect the ammeter the car should draw severalamps until it goes into "sleep" mode which can take several minutes.Normal sleep mode drain should be 30 milliamps or less by GM standards. You willneed an ammeter that can transition from whatever the drain is down into thesleep mode. If you have a drain I suggest the following:

Once you determine you have a drain with an ammeter what Irecommend first is to listen to each fuse box and see if you hear any relaysoperating. If not, then place your hand on each relay to see if any of themfeel hot. That can be the start if you find something like that is happening.

If nothing shows up you can hear or feel then I recommendyou separate the two fuse boxes from each other. This is easy and done byremoving the Red cable from the engine fuse box that feeds the passenger fusebox. It is on the right rear side of the engine fuse box. There is a stud therewhere the large Red wire from the battery connects. Just remove the nut anddisconnect the large Red wire feeding the passenger fuse box and reattach theRed battery cable. NOTE: I would recommend disconnecting the negative ammeterhookup when working on the positive side doing this.

What you will be doing is measuring the drain with anammeter to see if disconnecting the passenger fuse box causes the drain to goaway or not. By depowering the passenger fuse box you will depower the BCMwhich controls the sleep mode so do not expect the sleep mode to happen.

If removing the feed to the passenger fuse box you then seeyou have eliminated the drain then you know it is something related to thosecircuits. If it does not reduce the drain then you know it is related to theengine fuse box. It could be a rare case where you have some drain via bothfuse boxes and we can deal with that if you think it is the case.
Just so you know, even though it may appear to be a problemin the engine or interior area the fuse boxes do feed circuits to each otherthat are not affected by separating the boxes. So, separating the fuses boxescan tell you how to narrow down your search but still not where the issue maybe. That is where the schematics come into play to track down the “real”culprit. Hope that makes sense.

Once you basically know where it is then you can removefuses and relays to see where the drain is coming from.
PS: There are cases where the alternator causes a drain soit can be disconnected and see if the drain drops.


Mr. Sam

 
That is a normal relay sound. You will get a couple of amps current flow until the BCM goes into sleep mode which can take several minutes. Some of what you saw was the hood light since I bet you didn't remove it.

In case you need it:

Here is some info for determining if you have a parasiticdrain. Let me know if I need to clarify anything of if I can help in any way.

Suggest you remove the hood light bulb first so it does notprovide a drain.

For measuring battery drain I would hook up an ammeter tothe negative side of the battery by removing the negative cable and measurebetween the cable and the negative battery post.

When you connect the ammeter the car should draw severalamps until it goes into "sleep" mode which can take several minutes.Normal sleep mode drain should be 30 milliamps or less by GM standards. You willneed an ammeter that can transition from whatever the drain is down into thesleep mode. If you have a drain I suggest the following:

Once you determine you have a drain with an ammeter what Irecommend first is to listen to each fuse box and see if you hear any relaysoperating. If not, then place your hand on each relay to see if any of themfeel hot. That can be the start if you find something like that is happening.

If nothing shows up you can hear or feel then I recommendyou separate the two fuse boxes from each other. This is easy and done byremoving the Red cable from the engine fuse box that feeds the passenger fusebox. It is on the right rear side of the engine fuse box. There is a stud therewhere the large Red wire from the battery connects. Just remove the nut anddisconnect the large Red wire feeding the passenger fuse box and reattach theRed battery cable. NOTE: I would recommend disconnecting the negative ammeterhookup when working on the positive side doing this.

What you will be doing is measuring the drain with anammeter to see if disconnecting the passenger fuse box causes the drain to goaway or not. By depowering the passenger fuse box you will depower the BCMwhich controls the sleep mode so do not expect the sleep mode to happen.

If removing the feed to the passenger fuse box you then seeyou have eliminated the drain then you know it is something related to thosecircuits. If it does not reduce the drain then you know it is related to theengine fuse box. It could be a rare case where you have some drain via bothfuse boxes and we can deal with that if you think it is the case.
Just so you know, even though it may appear to be a problemin the engine or interior area the fuse boxes do feed circuits to each otherthat are not affected by separating the boxes. So, separating the fuses boxescan tell you how to narrow down your search but still not where the issue maybe. That is where the schematics come into play to track down the “real”culprit. Hope that makes sense.

Once you basically know where it is then you can removefuses and relays to see where the drain is coming from.
PS: There are cases where the alternator causes a drain soit can be disconnected and see if the drain drops.


Mr. Sam

Thank you, MR. SAM.......I really do appreciate all your help...... I have an aftermarket C5R hood with no light, so thats definitely not an issue.... as far as sleep mode..can i leave amp meter in series till sleep mode happens?????? Then id see all is normal, and wont go any further... thanks for responding
 
Yes, the idea is you put the ammeter on to measure any parasitic draw and let it go to sleep made (if it does) and see what the draw is. 17-30 milliamps is OK. Let me know if you have any questions.


Mr. Sam
 
I'll bet you have no parasitic draw if all you got was about 2 amps before sleep mode. You might need an ammeter that will have an auto mode to move from an amp setting to a milliamp setting.


Mr. Sam
 

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors

Dealers:

MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Advertise with the Corvette Action Center!

Double Your Chances!

Our Partners

Back
Top Bottom