2.5 amp parasitic draw on battery

[murphthelab]

Not sure what to check next???

1) Battery warning light came on mid-trip. Some other random warning lights came on and off right afterwards as well.
2) Drove the LC home so as not to get stranded.
3) Checked the battery voltage next morning. Read 2 to 3 volts.
4) Disconnected and charged the battery overnight.
5) Post-charge battery was healthy 12.8 volts. Installed and started LC. No warning lights. Checked running voltage ~14 volts.
6) At this point, not sure that either battery (relatively new) or alternator are the issue. Haven't fully tested, but initial indications are they look OK. Leave the vehicle overnight.
7) Re-check batter in the morning. Back down to ~2 or 3 volts.
8) With LC in all-off state, connect amp-meter on neg terminal. Read a 2.5 amp current.
9) Pull all fuses consecutively in engine and driver side junction boxes. No change to 2.5 amp draw.
(Note - I did not remove the two major fuses in the Fusible Link Block near the positive terminal. Those 100a and 140a fuses are hard bolted in. One is for the alternator circuit I believe.)

Stumped. Is the 2.5amp going to something that's not fuse protected? Do the relays play any role in troubleshooting here (I think not)? I assume if there is a relay, there is also a fuse in the circuit.

Help please.
Cheers,
John B
1998 Landcruiser

 

[e9999]

wow.
no specific suggestion, but be careful. 2.5A is an awful lot. Like a fridge. Something may be getting hot someplace and your battery won't handle this deep discharging very long -unless it's a deep cycle one-.
I would assume that all the circuits are fuse-protected according to their specific gauge.
You sure you did all the fuses? Has there been any electrical add-ons or mods?

 

[hankinid]

Not sure what to check next???
...9) Pull all fuses consecutively in engine and driver side junction boxes. No change to 2.5 amp draw.

(Note - I did not remove the two major fuses in the Fusible Link Block near the positive terminal. Those 100a and 140a fuses are hard bolted in. One is for the alternator circuit I believe.)

Stumped. Is the 2.5amp going to something that's not fuse protected? Do the relays play any role in troubleshooting here (I think not)? I assume if there is a relay, there is also a fuse in the circuit.

Help please.
Cheers,
John B
1998 Landcruiser

I'd check all fuses, including those on the + terminal fuse block as well as the big fuses in the underhood box...they'll be closest to the inner fender panel.

Relays are usually fused on the hot line to the relay contacts. In theory you could have a relay that won't unlatch when power is removed, but that's not a common failure mode.

hth

Steve

 

[agaisin]

9) Pull all fuses consecutively in engine and driver side junction boxes. No change to 2.5 amp draw.

There's also a junction box on the passenger side. I don't know if it's downstream of the Engine J/B and the other one or not.
Also, has the battery been tested? Voltage reading being 12.8 doesn't mean it's holding the voltage properly and the battery itself could possible be the problem. Since it's free and easy, I would take it somewhere to get a battery/starter/alternator test.

I hope this isn't offensive, it's not intended to be, so I'll throw it out there. (I learned a few things about multimeters the hard way recently). If you are at the point where you can't logically explain the current reading (s) you're getting here are some thoughts:
1) if multimeter battery is low you can't rely on the readings
2) verify your parasitic draw with a second multimeter
3) are you sure you're using the multimeter correctly (probes in the right place), units set correctly (2.5A and not mA etc...),
4) Does your multimeter have fuses for the current readings? If so, make sure they're good.
5) How are you checking for parasitic draw - what are you connecting to the pos/neg probes?

Sorry if your level of knowledge way exceeds my suggestions.

 

[murphthelab]

I did check the big fuses in the underhood box near the fender. Those checked out.

I also did unbolt the two big fuses in the Fusible Link Box. When I took out the one labeled "J/B No. 2", the amperage dropped to near zero. So whatever is drawing is on that circuit.

Does this actually help me? Is this 100 A fuse just a link to the downstream fuse box in the driver side well?

 

[murphthelab]

Thanks for suggestions agaisin. No offense taken.

I do have two multimeters, but I can't verify the current measure because one has a blow fuse. Yes, I've also learned the hardway, especially when it comes to forgetting to swap the probe leads.

I'm pretty confident that ammeter is working correctly, and I'm measuring on a 10 amp range. I'm measuring directly from negative battery terminal to disconnected cable. Pulling the 100 A fuse as described above shows that something finally eliminated the current draw. Still not sure what all is on that circuit.

I reconnected the battery and started the vehicle and checked out all the obvious electrical gadgets (windows, lights, radio, circuits, etc.). All seems to check out.

However, when I measured the running battery voltage, it now measures almost 17 volts. Isn't that high? Does that point to an alternator issue?

 

[agaisin]

If I'm reading the wiring diagram correctly, it looks like the J/B No. 2 leads to the driver side j/b. PM me your email and I can mail you the wiring diagrams if you don't have them already.

 

[agaisin]

However, when I measured the running battery voltage, it now measures almost 17 volts. Isn't that high? Does that point to an alternator issue?

Spec for Alternator output on our vehicles is 13.2-14.8 volts, so yes, I believe 17V is high and yes I believe it points to a bad voltage regulator in the alternator.
I don't know if/how that is related to the parasitic draw.

----------------
From the FSM:
9(b) Check the charging circuit as follows:
With the engine running from idling to 2,000 rpm, check
the reading on the ammeter and voltmeter.
Standard amperage:
10 A or less
Standard voltage:
13.2 - 14.8 V
If the value is not specified, check the generator.

10. INSPECT CHARGING CIRCUIT WITH LOAD
(a) With the engine running at 2,000 rpm, turn on the high
beam headlights and place the heater blower switch at HI.
(b) Check the reading on the ammeter.
Standard amperage:
30 A or more
If the ammeter reading is less than the standard amperage, repair
the generator.
HINT:
If the battery is fully charged, the indication will sometimes be
less than standard amperage.

 

[Anthony.L]

17v is WAY high and got to be close in frying some sensitive stuff. The alternator should be putting out a max of around 14.2V give or take depending on engine RPM.

 

[murphthelab]

The FSM specs 13.2 to 14.8 volts when you measure from ground to "Terminal B" on the generator.

I was measuring directly across the battery terminals when measured almost 17 volts. I'm not sure where terminal B is exactly. I do know that access to the alternator isn't easy. Seems I would need to remove the engine under cover (metal) to access from below. Getting my hands in there from above is a bit difficult, and you really can't see what you're doing at all.

So do I need to get under and perform this removal to get things clarified? Or does the 17v battery terminal measurement say enough?

 

[mobi-arc]

Take a piece of jumper cable, bond one end to alternator casing and bond one end to the battery negative terminal. Re-run your test and see if you still have 17 volts. If you do, then you may have resistance on the positive side of the current path, or you may have a voltage regulator that's faulty. If the voltage drop back to 15.5 to 14.9, then you have a grounding issue. That gives you some direction on the high voltage issue. For the parasitic draw, it might be a faulty alternator and 2.5 amps is approximately what the rotor draws. This would also be a function of a faulty voltage regulator. You could disconnect the alternator and see if you continue to have parasitic draw. If so, the alternator has to come out and the regulator needs to be swapped.

 

[mobi-arc]

The FSM specs 13.2 to 14.8 volts when you measure from ground to "Terminal B" on the generator.

B terminal on the generator is the alternator output post which should be common with the battery post.

 

[LandCruiserPhil]

Because your reading are all over the place can you provide a detail on exactly how you using your meter when testing for amps and volts? It sound like possible your meter settings are not where they should be.

 

[Sandroad]

I hope this doesn't confuse the issue, but some of these numbers have been bugging me. A fully charged battery in good condition would be able to handle a 2.5 amp draw for many hours, including overnight, without dropping to 2-3 volts. That low of a voltage may indicate a faulty cell in the battery. Did the over-charging (17 volts would be over-charging, if that's what the alternator is putting out) damage the battery? On the other hand, it may have been the other way around, because a battery going bad can do flaky things to electronics. If it was my truck, I'd swap in a known good battery and re-check the alternator and parasitic draw voltages. And, if you have any reason at all to question your multi-meter, auto-scale, digital readout, hand-helds are now very inexpensive.

 

[murphthelab]

Thanks guys for the further insightful inputs. I did physically trace the so-called "J/B No. 2" fuse near the positive battery terminal. This 100amp fuse sits between the alternator and the fuse junction box. One side of this fuse is directly connected to so-called Terminal B on the generator.

With the engine running, I measured almost 18 volts between ground and this terminal (tied to Terminal B). I did this with two different meters. I also see clear signs of excessive voltage, ala the strange warning lights lighting intermittently on the dash (e.g., ABS). So I am convinced the regulator is faulty here.

While it appears that the voltage irregularity is intermittent, I can't see any other reasonable explanation for why 17 or 18 volts would come off the generator unless the voltage reg is faulty. So that's where I'm headed...

Fingers crossed, because I just completed removal of the alternator. Not fun, especially for a 14 year old LC from the Northeast rust belt. I can comment, like another poster in another tread, the 1998 LC does allow you to remove the generator thru the bottom w/out removing any coolant parts of pulley wheels. Furthermore, the removal of the 3-wire connector and the other wire connections to the alternator WAS in fact the hardest most frustrating part.

So I'll get my rebuilt DENSO unit tomorrow. Swapping the whole thing and not just the regulator ($175 shipped - Amazon). Fingers crossed that the mysteries all end when I get it put back together.

Will advise.
Cheers.