Amp / Voltage draw issue.

[robbz28]

I have a problem and I wanted to just throw this out there before I break my multi-meter out and start poking around on the car. I have something, somewhere sucking the life out of my battery over the course of a week. I thought maybe I had a bad battery, took it to Autozone today and they tested it and said all's well. So are there any "usual suspects" as far as these cars go with this issue? I know my dome lights, under-hood lights, courtesey lights, and glove box lights are in working order. The radio is stock, but there is an aftermarket amplifer wired in to replace the bose speakers, but the power light on it is off when the car is. Maybe a stuck relay or something?? Where to start? What to do? My little 1.5 amp battery charger stays on it in the meantime.

[-=Jeff=-]

my best suggestion is to connect the multi-meter and pull one fuse at time and watch the current level..

but before that.. what was the last thing done to the car prior to this occurring?

[GOLDCYLON]

Check the map lights in the visor as well. Is this a combo top and side post battery you have? G C

[secondchance]

Check and make sure door switch for courtesy light is working - shutting off after 15-20 seconds. These switches has been known to go bad.

[robbz28]

Its been like this since i got the car...it sits for longer than a week and it needs a charge. I have had the car for about 6 weeks. It is a side post battery and the lights do turn off. The visor lights are off as well.

[-=Jeff=-]

Next I would suggest disconnecting the Stereo aftermarket amp and see if that fixes it..

Is there an aftermarket keyless entry or alarm on it?

[ghlkal]

Next I would suggest disconnecting the Stereo aftermarket amp and see if that fixes it..

Is there an aftermarket keyless entry or alarm on it?

These are both good suggestions. On my 85, it came with a bunch of stereo stuff. Even with it all shut down, it was still pulling power and would drain the battery until I finally pulled all of it out.

On my Z, the PO put in an aftermarket alarm system. What a PITA. It will suck the battery down after a week. It's on my list of things to pull out this winter.

[WVZR-1]

I agree with -=Jeff=- but first establish what the simple parasitic draw actually is. Do you have a DVM? Set your DVM to either 10A or 20A and with the DVM connected between the negative terminal of the battery and the negative cable see what it actually is. Make sure the car has "gone to sleep" - "key off" or in your pocket. If you've got something very low maybe 30 milliamps or less it says maybe you don't. An early 90's car you might expect maybe as little as 20 milliamps or so to be the norm. Never checked mine.

If you've got something larger than that could be as high as 2 - 3 Amp or so you then start to pull fuses one at a time and monitor the drop. When you pull one that dramatically lowers the draw to an expected value then you search that circuit. I was always told to pull lower amp fuses first (don't know why) and do larger value and breakers last.

I was also told to do this first but don't remember ever doing it. Remove both battery cables and check Ohms across the battery cable ends. Something very low hints major shorts.

I don't recall how easy the red wire is to get to on the alternator but a bad diode will take a battery down pretty quick. You could remove it to check also.

It's much easier for me to walk to the car and do it than it is to try and explain it but I just wouldn't start tearing into things. I'd measure the drain before I even worried about the amp. I might make the amp first after the check though.

[robbz28]

I plan on measuring and testing...looks like i have something to do this weekend...

[WVZR-1]

I plan on measuring and testing...looks like i have something to do this weekend...

I'd maybe ask someone with a '91MY to check theirs for a good reference for the basic test. That might give you a "target"! If you go to a FSM it will ask you to add circuits to arrive at a value. A known good starting point might be my best thought of the day!

[scottfab]

Check the map lights in the visor as well. .. snip...

and the light that goes on when you open the center console.
If it is out of adjustment .... kills battery. if it stays on when the lid
is shut.
This one I know :cry:

[robbz28]

and the light that goes on when you open the center console.
If it is out of adjustment .... kills battery. if it stays on when the lid
is shut.
This one I know :cry:

That light don't work, not sure whats up with that, I tried to change the bulb and that didnt help, I hooked a test light up to it and got nothing...such an insignificant thing I'll worry about it later, but it might be a related incident (or just a bad connection). Anyway, I got my notepad out and hopefully this weekend can recruit my brother (a fellow zr1 owner) to help me pinpoint my issue.

[GOLDCYLON]

Its been like this since i got the car...it sits for longer than a week and it needs a charge. I have had the car for about 6 weeks. It is a side post battery and the lights do turn off. The visor lights are off as well.


Based upon this response. Time to move onto -=Jeffs=- suggestion. Your brother can help you out during the fuse pulling multimeter process. GC

[Corbusa]

Mine does the same thing , It / mine is just as ghlkal said , I have both after market stereo and aftermarket alarm . I like both features so I keep it on a trickle charger..

[scottfab]

Mine will last about 2-3 weeks without a trickle charger.

Here is the manual page with the table of what things should
draw what current. It requires the DVM be put inline with the battery as
has already been suggested.

http://zr1.net/forum/picture.php?albumid=199&pictureid=1481

[gbrtng]

I plan on measuring and testing...looks like i have something to do this weekend...
I just measured my 91 with a clip-on DC ammeter - I see 0.010 to 0.020
amperes on a meter with 0.00 resolution. So it's safe to say that my stock
ZR-1 draws less than 30 milliamperes at rest. I think the manual says less than 50 milliamperes, but that's from memory ...

[WVZR-1]

I just measured my 91 with a clip-on DC ammeter - I see 0.010 to 0.020
amperes on a meter with 0.00 resolution. So it's safe to say that my stock
ZR-1 draws less than 30 milliamperes at rest. I think the manual says less than 50 milliamperes, but that's from memory ...


That's what he needed for a start and I believe everything that I've ever seen wanted less than 30Ma, 20Ma is great, FSM says "add circuits" and most electrical shops will accept less than 50Ma. Looking at the FSM information posted after checking the AMP I might go directly to the "HEADLAMP MODULE". If a headlamp has worn bushings and maybe doesn't complete the "park" I imagine that would likely be a substantial draw.

[robbz28]

That's what he needed for a start and I believe everything that I've ever seen wanted less than 30Ma, 20Ma is great, FSM says "add circuits" and most electrical shops will accept less than 50Ma. Looking at the FSM information posted after checking the AMP I might go directly to the "HEADLAMP MODULE". If a headlamp has worn bushings and maybe doesn't complete the "park" I imagine that would likely be a substantial draw.

Well this made me take notice...I wish i wasnt stuck at my desk or I'd go check some things out, but my headlights are in need of repair, the drivers side has a bad gear and don't open all the way without a little help. It definately has a stripped tooth somewhere, and when it closes it keeps running and bumping for a few seconds afterward...so it may not be completing the "park" either as you put it...

[robbz28]

I also just got online and ordered me a pair of bronze headlight gears...gonna fix that while im at it.

[WVZR-1]

I also just got online and ordered me a pair of bronze headlight gears...gonna fix that while im at it.

You might have over reacted just a bit there but that's not a big deal. If the gear package includes the bushings fine if not you need to get some of those also. A MAM kit I think is both. Here's what I meant when I mentioned "bushings" and there's three per side:
http://www.zip-corvette.com/_Images/Blobs/HDL-242.JPG

The gears aren't often needed but if you're in there why not. I'd only be concerned with the electrical diagnosis this time. Check the draw first before tampering with the head lamps. If you show "no draw" then I'd cycle the lamps before I did any thing else and when they don't park or stutter check the load again.

Here's a link "DaveK" posted regarding the H/L repair: http://home.comcast.net/~zrjuan/headlight.html

[robbz28]

Ok so i get home and look for my.good multimeter and cant find it so i grabbed my 10 dollar special analog meter set it to 50 mA DC and put it between the negative battery cable and the post and it pegged out my meter for a second and popped the fuse in it...so i just left the negative cable unhooked and came in...got to get some fuses and find my digital multimeter...

[robbz28]

You might have over reacted just a bit there but that's not a big deal. If the gear package includes the bushings fine if not you need to get some of those also. A MAM kit I think is both. Here's what I meant when I mentioned "bushings" and there's three per side:
http://www.zip-corvette.com/_Images/Blobs/HDL-242.JPG

The gears aren't often needed but if you're in there why not. I'd only be concerned with the electrical diagnosis this time. Check the draw first before tampering with the head lamps. If you show "no draw" then I'd cycle the lamps before I did any thing else and when they don't park or stutter check the load again.

Here's a link "DaveK" posted regarding the H/L repair: http://home.comcast.net/~zrjuan/headlight.html

The new bronze ones come with the bushings...and like you said...while youre in there why not fix it for good.

[gbrtng]

Ok so i get home and look for my.good multimeter and cant find it so i grabbed my 10 dollar special analog meter set it to 50 mA DC and put it between the negative battery cable and the post and it pegged out my meter for a second and popped the fuse in it...so i just left the negative cable unhooked and came in...got to get some fuses and find my digital multimeter...
There's quite a current inrush to the system when you connect the battery cable - probably on the order of 10s of amperes as the headlight controller and other systems come to life. So it's tricky to measure the current initially, but the current draw settles down after a second or so. Remember that there are two fuse panels (one at the end of the dashboard and the other under the dash on the passenger side) and the 6 or 7 fusible links
connected to the terminal behind the battery. So there's a lot of stuff to disconnect one at a time whilst trying to find the offending circuit. My best guess is to look for whatever aftermarket stuff you have first. The factory circuits that fail are likely due to sticking relays - like the fuel pump. Good luck ...

[robbz28]

Ok so i got my good multimeter and set it to volts this time...between the ground cable and negative terminal it read 12.83 volts. I flicked it to 200ma fused and it pegged and popped my fuse. Sooooo maybe alternator diode??

[WVZR-1]

Ok so i got my good multimeter and set it to volts this time...between the ground cable and negative terminal it read 12.83 volts. I flicked it to 200ma fused and it pegged and popped my fuse. Sooooo maybe alternator diode??

What brand and model meter? There's a "rush" initially like mentioned earlier. Set your meter to AMPS not Ma and make sure the cables are in the correct ports. Set to AMPS before using! It sounds like you're mentioning you switched it "while connected". Don't know?

[-=Jeff=-]

Post a Picture of the Multimeter or the brand and Model and we will figure out the correct connections for you

[robbz28]

Its a craftsman 82141. I didnt switch it while connected. The batter had been unhooked for a whole day when i tested it. I would post a pic but not sure how to do that from this phone. I put it on 200 ma ac

[-=Jeff=-]

Ok set the meter to the 10A setting. Leave the black lead in the middle plug. Put the red lead in the left plug. Assuming you have the + off the battery. Red goes to battery + black to + cable. Everything off see what the drain is.

[robbz28]

Well dumb old me...i didnt pay attention to the ac/dc settings. I switched it to 200m dc and it reads a 2.7
I blew the fuse on the 10 amp leg. I will see if i can find a replacement tomorrow.

[robbz28]

Ok set the meter to the 10A setting. Leave the black lead in the middle plug. Put the red lead in the left plug. Assuming you have the + off the battery. Red goes to battery + black to + cable. Everything off see what the drain is.

Ok so i unhooked my headlights and underhood lamps (they would try to run when i xonnected the meter) I set the meter like you said and got .27 volts i did it on the negative side as well and got .27 volts again.

[WVZR-1]

Ok so i unhooked my headlights and underhood lamps (they would try to run when i xonnected the meter) I set the meter like you said and got .27 volts i did it on the negative side as well and got .27 volts again.

I saw the meter maybe a little differently but I anticipated something less than 200Ma. First hook everything up! Battery positive stays connected. Put the black in the COM port and the RED in the RH port, turn the meter to 200m at 3 o'clock. Let the car "rest". Remove the negative cable and put the meter between negative cable and the negative post. What have you now? I believe the meter will put "decimal" in the correct location.

Using the 10A left port you would put the meter at 1 click past 3 o'clock, we'll call it 3:30. What does the meter read using those? Maybe it is wise to maybe do a 10A first.

You unhooked the headlamp control module on the left front wheel liner?

You bought a couple fuses?

[robbz28]

I cant hook my headlights up..my gears are bad and they spin for 5 seconds ish when they get juice and that is too much for that meter...

[WVZR-1]

I cant hook my headlights up..my gears are bad and they spin for 5 seconds ish when they get juice and that is too much for that meter...

Gotcha! Well then with the headlamps out of the equation I'm assuming you're at 27Ma which is acceptable. Check it maybe one more time using the 200Ma (3 0'clock)and the RH port. You were using the 10A at 3:30?

You could use your meter on another car to confirm the interpretation of the meter. Unhook the negative on something else and check it with the 200Ma & RH port and then the 10A using the LH port!!

[robbz28]

Iok i checked it like you said on the 3 o clock 200m it was 2.7... and yes earlier when i tested it it was at the 3:30 10a spot. I guess its my headlights...maybe the relay or something never rests? Oh well they will be fixed next weekend and i can re-test.

[robbz28]

Well the draw might still be there but it hasnt had any effect on the power this thing has got...just in from my regularly scheduled weekend clutch thrashing...shr really likes this cooler dryer air we got down here this weekend! 40 mph second gear she lit the tires up...a good day.