Slow drain on battery 1996 D1 SD

[terryjm1]

I have a 96 D1 SD. A couple months ago it started having issues with a slow drain on the battery. After 3 days of sitting the battery is so far down it doesn’t have enough power to start the engine. If I disconnect the negative cable, the battery stays charged. So, I think I can eliminate the battery being a problem.

In my general car experiences my first stop would be the power seats. It’s an SD and does not have power seats.

My next stop would be the power locks, which it does have. After that I’d suspect power windows.

Before I start pulling fuses to check for a draw one by one, is there a common fault to look for with a slow battery drain?

 

[terryjm1]

I will also add that is is completely stock. There are no aftermarket add ons at all.

 

[robertf]

In my experience its either an obd2 accessory keeping the ecm awak, or a failed alternator diode. Pop the hood and listen for a faint high pitched whine from the alternator with the vehicle off

 

[terryjm1]

In my experience its either an obd2 accessory keeping the ecm awak, or a failed alternator diode. Pop the hood and listen for a faint high pitched whine from the alternator with the vehicle off

I have been getting a code for the coolant temperature sensor… that I replaced for the same reason about a year ago. But… it wasn’t draining the battery then.

I will take a look at the alternator diode as my next step.

 

[LRDONE]

You should do a parasitic draw test. Then you can see how much of a draw you have.

 

[special ed]

Not much that is common to do that. First thing that comes to mind is aftermarket LEDs anywhere in the car. tail lights, dome lamps... secondly is the alternator. Check to see if the center shaft of the alternator is magnetized. after those 2 things connect an DVOM on the battery and start pulling fuses.

 

[terryjm1]

I got back to this problem today. As it was easy to just swap in another alternator, I decided to do that. As I was removing the three wires at the back of the alternator I found one not tightened, not even finger tight. As I already had a spare known good alternator (newer rebuild from a parts rig) ready to go and was almost done removing the suspect one, I swapped in the other one.

The previous owner had a used engine installed and I have found other odds and ends not quite complete. I should have checked this first.

The loose wire was one of the small ones. I believe it was the “exciter” lead. It seems odd to me that would be causing a slow drain. The alternator was charging as running it would get the battery recharged.

Think this is related?

0n a sort of related note, when I got in it this morning to take it to my shop, the factory head unit stopped making sound. It comes on and the display works, but no sound. Bummed…

 

[Levi]

When its dark check if you can see any light coming out of your glove box. My glove box light was not shutting off and draining my battery.

 

[terryjm1]

When its dark check if you can see any light coming out of your glove box. My glove box light was not shutting off and draining my battery.

My son does like to mess with the glove box and has gotten paperwork in the glove box jammed in it. It has randomly popped back open later and I discovered the paper jam. Good call, I will check that.

 

[robertf]

glove box lamp power comes from the running light power. If the lights are off it shouldn't be on.

 

[robertf]

Also, check the amp fuse.

LSE amps are easy to kill if you flood it. Any chance of that?

 

[terryjm1]

Not an LSE but the amp did cross my mind when the sound stopped today. I will check it. Thanks!

 

[DiscoClay]

I am dealing with a drain as well; but my NAS 95 disco is running the stock 14CUX computer (aka: "pre-GEMS"). I currently have it narrowed down to the main fuel injection circuit (the 60 amp fuse under the hood) and the alternator circuit.. I suspect the alternator circuit is a red herring (or a false flag, you pick .

Anyone have suggestions on the ~5amp drain from the injection circuit? (and should I start a separate thread, given it's 14CUX rather than GEMS?)

 

[boxster]

I am dealing with a drain as well; but my NAS 95 disco is running the stock 14CUX computer (aka: "pre-GEMS"). I currently have it narrowed down to the main fuel injection circuit (the 60 amp fuse under the hood) and the alternator circuit.. I suspect the alternator circuit is a red herring (or a false flag, you pick .

Anyone have suggestions on the ~5amp drain from the injection circuit? (and should I start a separate thread, given it's 14CUX rather than GEMS?)

How are you testing the the circuit?

 

[DiscoClay]

How are you testing the the circuit?

Step zero: turn the ignition off.
Step one: wire a light between one of the battery terminals and it's lug (in this case, I put the light between the negative lug and the negative terminal cables).
/// result: lightbulb illuminates, indicating current flowing
Step two: Remove all fuses from the mains fuseblock (underhood, next to battery)
/// result: the light goes out, indicating no current flowing
Step three: re-insert fuses, one at a time until the light comes on; note the related circuit.
Step four: chase that circuit... suspect stuck relays. suspect bad diodes in the Alternator's bridge rectifier.

I am currently investigating the fuel injection circuit(s)... well, when my day yob is done for the day ...Anyone with a similar experience or better process, please pipe up )

 

[terryjm1]

I replaced my alternator with a known good spare. I still have the problem. I thought I had it corrected and left the battery connected. I became busy with other things and left it for over a week. I came back to a ruined battery. Good news… one of the few things I like about Walmart is their battery warranty. New battery in hand and I don’t want to ruin it.

Im also a bit thick headed… can you further explain the following? I think I understand but can you explain it like I am a 5th grader?

“Step one: wire a light between one of the battery terminals and its lug (in this case, I put the light between the negative lug and the negative terminal cables).”

I read that as disconnect the negative battery terminal and wire a light between the cable and the battery post, correct?

 

[DiscoClay]

5th graders are remarkably lucid with basic instructions.. it's us post-puberty types that overcomplicate things.

Here is a better description:

0. turn the key OFF
1. Disconnect the Negative Cable from the Battery Terminal.
2. connect a lightbulb (an LED will probably work fine too) between the negative cable and the negative terminal of the battery... aka: a test light
3. if current is flowing in your electrical system, the bulb will illuminate; little current: dim light..lots of current: bright light.. SHITTONNES of current: bulb pops (aka: let the smoke out).

basic example:

Basic idea: (arrows go to normal battery connections)

 

[terryjm1]

I do have a test light and tried this method. With ignition off and all doors closed, no light, not even a dim light. I opened the passenger door and what was odd to me is the light flashed on and off. What is up with that?

I was really hoping the light would have been at least dim as that would have given me a start on finding the problem. I guess I will install the new battery and see if it loses charge over a few hours.

 

[LRDONE]

Use a volt meter and measure milliamps, that's the professional approach. Hook the meter up from the negative post to the negative terminal with the negative terminal still connected. Shut all your doors and lock the truck. Then disconnect the negative cable with your volt meter wired how I previously stated. At that point you can literally watch all the modules go to sleep. Shoot for less than 50 milliamps, If you aren't there, start pulling fuses until you get there. I run this test on a lot of old cars pretty regularly to locate a draw. It's quick and simple.

 

[DiscoClay]

A test light is also *quite professional*, I and my master mechs have used them for years The benefit: you can see it... Especially if you are testing fuses and relays from various locations.

Be careful using the ampere function on your multimeter (*have a spare fuse or two on hand) because if you have a moderately strong drain you will pop the meter's fuse (if it has one).

If you are not seeing any illumination from your test light (and presuming your test light is sensitive above about 100 milliamps [aka: 0.01amp) then LRDONE's milliamp test is the next step in the chain. That said; a 50ma drain would not kill a healthy group24 battery in ~3 days, rather it should take about a month.

Here is a good generic description site: https://www.batteryskills.com/how-to-check-for-a-draw-on-a-car-battery-with-a-test-light/
Their overview page is very good: https://www.batteryskills.com/troubleshooting-battery-problems/

Here is great site that talks about parasitic draw and actually did the math (so I don't have to : https://homebatterybank.com/how-fast-will-a-car-battery-drain/