A little help with a parasitic draw.

[SlimPickins]

Hey guys, so my battery has been petering out over the course of a week or so if not hooked up to a trickle charger. I have a '98 with 168k miles, the battery is from Autozone, maybe a year old. I did a parasitic draw test and have a 700ma or so pull. I went through the rigmorole of pulling all of the fuses under the dash, the engine bay fuses and the alternator. No luck. Everything is OEM except for a small module that appears attached to the windshield with a small antenna and a coax cable going into it. I removed the coax cable. Nothing. I do see a solo fuse attached to some free wiring that I can't immediatly ID. Any thoughts? I've read that the starter can also be an issue but I figured it'd probably draw more than 700ma if that were the culprit. But, the heel do I know..? I like wrenches better than multimeters. They hold up better when you throw them.. Thanks for any input!

 

[Michael Brown]

I would suspect it is something to do with that added wiring, but not sure on its purpose. CoAx cable is probably for an antenna of some sort. Maybe a HAM or CB module was installed at one point.
I'd recommend a cheap clamp meter. Klein makes a pretty good one, but a cheaper one should also work. Just check the low amperage range.
You can put the wires from that "addition" in the clamp to check the amperage draw. Just keep checking wires until you find the source(s) of the 700mA.

 

[Buddha.]

If you buy a cheap meter with an amp clamp triple check that it can measure DC amps not just AC amps.

 

[Salonika]

You can also buy a fuse that you can install a jumper wire on, to use with a DC clamp amp meter, then you move the fuse around until you find a circuit with juice flowing. That will get you closer faster.

 

[CharlieNorth]

That 700ma draw is generally keep alive power for the ECU and other modules in the vehicle. Has this battery been draining since purchased and do you have another battery to swap in and see if the problem follows the battery.
Not everything that is new is guaranteed to be good. Which is why we have warranties.

 

[SlimPickins]

That 700ma draw is generally keep alive power for the ECU and other modules in the vehicle. Has this battery been draining since purchased and do you have another battery to swap in and see if the problem follows the battery.
Not everything that is new is guaranteed to be good. Which is why we have warranties.

Thanks for the feedback guys. I’ll check into borrowing a meter with a clamp from a buddy. Everything I’ve read says that a normal draw is typically under 50-65ma, I’m over 10x that. Does our ECU, etc. really draw that much vs other vehicles? Again, I’ve been lucky that most of my vehicles over the years have had only mechanical issues that I’m usually able to sort out. Electrical is a pretty new venture. Thanks again.

 

[SlimPickins]

I have gone through three different batteries and each has been drained flat if I don’t have my trickle charger connected. Even with the trickle charger, they’ll eventually drain, just takes longer.

 

[CharlieNorth]

I think you are correct, these ECUs do not draw that amount, I found C4 Corvettes draw around that but I last worked on that problem 35 years back.

 

[CharlieNorth]

Right on the battery you have a few wires coming off. Have you disconnected the ABS feed? For a test if you have not done so, I would disconnect each circuit leaving just one on and check the draw.
In the fuse box right next to that, the bolt in fuses can also be isolated to check for a draw.

 

[SlimPickins]

One other thing I just discovered. Someone cut the wires going into the alarm horn. I pulled the alarm horn out from its home and it’s no longer connected to anything. Perhaps the alarm was going off randomly and previous owner just cut wires at the sound source vs fixing the problem. Maybe my alarm is going off (minus the audible noise of course) and draining?? I know there is a great write up on disabling alarm by jlocster but I like having the key fob to open doors as my locks suck even after lubing. Maybe the alarm is a red herring..

 

[SlimPickins]

Right on the battery you have a few wires coming off. Have you disconnected the ABS feed? For a test if you have not done so, I would disconnect each circuit leaving just one on and check the draw.
In the fuse box right next to that, the bolt in fuses can also be isolated to check for a draw.

Ha! Was just about to check that!

 

[CharlieNorth]

Alarm is a good possibility, best I can tell my 95SR has no alarm but my Diamante alarm used to turn on at will, like park in the sun and lock it up it would go off.

 

[SlimPickins]

I'm not sure if this is relevant but when I remove my negative terminal from the battery and then reconnect, the hazard lights go on. I can hear the relay clicking in the fuse box under the hood and all four corner lights flash. Once I hit lock/unlock on my fob, it stops. The multi CD player (Mitsu) in the rear cargo area also cycles through trying to find a disc. I removed the CD cartridge to stop this as it was giving me fluctuations on my multimeter until it would cycle all of the way through the cartridge. This gave me a continuous draw of about 650ma. I got lucky and removed the first 10A fuse under the dash and the draw went down to 110ma. Still not optimal but a damn sight better than 650ma. According to one of the online resources (fuse-box-info., this is #13, 10A 'room lamps, clock.' I'd done this the other day without the same result so I'm not entirely sure why I got results this time through. Any recs on next steps? I'll check YouTube as well. Thanks again all.

 

[Salonika]

That’s not your hazard lights, it’s the alarm going off. Cutting the speaker wire kills the sound, my alarm horn was removed 15 years ago, but the lights still flash for the alarm. You are on the right path, process of elimination is the only way you will figure it out. The FSM has excellent coverage of all things wiring, including showing locations of everything.

 

[CharlieNorth]

Normal for the CD changer to cycle
Hazards, that might be the alarm going off. Not having the system would the headlights flash as well or just the hazards?