Mystery 16Amp battery drain HJ61, 12H-T 24V system - HELP needed.

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This is my daily driver. No warnings prior to this. Previous day the factory gauge was reading 26-27 volts like always.

I went to start my HJ61 and it was DEAD. No click, no lights, nothing. No lights are switches left on, door light was not on.
Battery#1 - 2.5Volts. Battery #2 - 7Volts.
Recharged each battery at low current overnight - took next day to O'Riellys where both batteries test fine. They said 95% capacity.
Put the batteries back in and hooked it up.
Measured voltage with DMM. Within a couple of hours, it was down to 19 Volts across both batteries.
Removed and Re-Charged batteries.
Got a 30Amp/75mV shunt to measure current at negative battery terminal. Measured 40mV or ~16A !!!!
One by one removed the connections at the + battery terminal.
The wire labeled "AM 1.25 B" is drawing ALL of the current. (this is now the ONLY wire connected at the + Battery terminal.)
I removed every standard fuse in the fuse box for kicks.
Still drawing 16A (if I let it sit, the current drops to about 13A after about 60 secs - don't want to leave it connected any longer).


PLEASE HELP
- What could be drawing this much current?
- What steps would you take next to diagnose?

Also, I loaned my FSM to a friend who is not available. Circuit diagrams appreciated.

20211020_182606.jpg
 
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Ladysmith
I'm going throught the same thing. Disconnect your batteries. Suspect burnt diode which will drain your batteries
really fast. Pull alternator and have it bench tested. Mines 12V. Brand new 120A alternator, good voltage when its running,
proper amp load when system loaded. I can't help further cause I had to go work and won't be home for weeks.
I ruined a pair of series 31 batteries. Good luck I'll follow along now and see what you get
 
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I'm going throught the same thing. Disconnect your batteries. Suspect burnt diode which will drain your batteries
really fast. Pull alternator and have it bench tested. Mines 12V. Brand new 120A alternator, good voltage when its running,
proper amp load when system loaded. I can't help further cause I had to go work and won't be home for weeks.
I ruined a pair of series 31 batteries. Good luck I'll follow along now and see what you get
I wonder if there are connections I can remove to test this theory? If I remove all wires connected to alternator would this eliminate the current, if the diode is the cause?
 
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Ladysmith
I’m just saying what I was told to do. IF it’s a diode, it’s gonna drain out your battery.
Being disconnected is safest bet to me. I am not an electrician by any means.
Unfortunately for me, some of the electricians I’ve used aren’t either.…..
 
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I have disconnected the alternator charging wire, the alternator plug, and the external regulator. No change.
I have disconnected the main glow screen wires just because I know these are capable of high currents. No change.

Still pulling 13-16Amps
 
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Hello
Have you looked at the cold start relay for the glow screen
Mine does the same for the first minute or 2 after starting
Maybe yours is stuck on?
Good Luck
Regards Alex
 
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Where did you "disconnect the glow screen wires..."? I would try disconnecting the glow plug relays. If you have super glow system start with the secondary glow relay first and see if that does it. Mine was stuck on and drained batteries flat overnight. I had the exact symptoms as you, no issues ever, then overnight dead ass batteries. I charged batteries and when I connected the leads back to the batts something was pulling a lot of current. Turned out to be the secondary glow relay was stuck on. On a 70 series the secondary glow relay is located in the inner fender well, next to the start relay (I would check/replace that too if original) I think this is a common issue with these older rigs, that along with the start relay going out and leading to all kinds of head scratching with not starting.

Check all relays that have power directly off the batt positive lead, I believe it is only the start and glow circuits, but maybe headlights too.

Hope this helps, good luck
 
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Where did you "disconnect the glow screen wires..."? I would try disconnecting the glow plug relays. If you have super glow system start with the secondary glow relay first and see if that does it. Mine was stuck on and drained batteries flat overnight. I had the exact symptoms as you, no issues ever, then overnight dead ass batteries. I charged batteries and when I connected the leads back to the batts something was pulling a lot of current. Turned out to be the secondary glow relay was stuck on. On a 70 series the secondary glow relay is located in the inner fender well, next to the start relay (I would check/replace that too if original) I think this is a common issue with these older rigs, that along with the start relay going out and leading to all kinds of head scratching with not starting.

Check all relays that have power directly off the batt positive lead, I believe it is only the start and glow circuits, but maybe headlights too.

Hope this helps, good luck

GLOW...
Attached 2 pics of what I believe to be the 2 glow screen relays. I disconnected one of the heavy wires on each of the relays (marked in green). Part number for these is 28610-57090 which google shows is RELAY ASSY, GLOW.
I disconnected these and there was no change - I still have the ~13-16amp drain.
The 3rd pic is of the connections at the glow screen. I DID NOT disconnect these - should I ? Seems I've eliminated glow by disconnecting heavy wire at relay.
Also note, it is warm here. Hasn't dropped below 50F / 10C in months.

HEADLIGHTS...
I disconnected the wires at the headlights, where they connect into the bulbs. Is it possible power could still be draining else where via the headlight relay if the bulbs are disconnected?

START RELAY...
I have not looked at this. I'm not sure what it looks like. I'll go looking.

20211021_082022_edit.jpg


20211021_082040_edit.jpg


glow.jpg
 
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Joined
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GLOW...
Attached 2 pics of what I believe to be the 2 glow screen relays. I disconnected one of the heavy wires on each of the relays (marked in green). Part number for these is 28610-57090 which google shows is RELAY ASSY, GLOW.
I disconnected these and there was no change - I still have the ~13-16amp drain.
The 3rd pic is of the connections at the glow screen. I DID NOT disconnect these - should I ? Seems I've eliminated glow by disconnecting heavy wire at relay.
Also note, it is warm here. Hasn't dropped below 50F / 10C in months.

HEADLIGHTS...
I disconnected the wires at the headlights, where they connect into the bulbs. Is it possible power could still be draining else where via the headlight relay if the bulbs are disconnected?

START RELAY...
I have not looked at this. I'm not sure what it looks like. I'll go looking.

View attachment 2817683

View attachment 2817684

View attachment 2817685


Glow Relays: I would disconnect both heavy wires from the relays, just to be sure. You should not need to disconnect the wires at the glow screen if both heavy wires are disconnected from the relays.

Head Light Relay: I would try to find it and disconnect that versus at the lights. Could be a dead short through the relay

Start Relay: May not help you, but 70 series it's located in the inner fender well, accessed from the engine bay. 70 series start relay looks like this:

relay old.jpg


I think 60 series relays are black in color, but same shape.

Chasing electrical faults is difficult, but since there are not many circuits tied directly to the battery it narrows it down some. There should be a HJ60 wire diagram on MUD which would help you trace everything that comes from the AM1 and GLOW fusible link block pictured in your first post.

If you can't find the HJ 60 wire diagrams, later today I could post photos of the 70 series wire diagrams. I would expect nearly the same circuits come off the battery.
 
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I found the starter relay and disconnected both plugs. No change.

Will go try svsisu's other recommendations.

In the mean time, I have discovered if I disconnect the breaker that the green arrow in the picture points to, the current drain disappears. Any idea what this is? It has a heavy-ish white wire coming in and a somewhat lighter-gauge red wire going out. The white is hot when the breaker is disconnected.

The part number (82650-12020) seems to be just a common breaker used in many Toyota applications.

underdash_edit.jpg
 
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That breaker is for "Breaker Assy, Wiring Circuit, No. 1" (what ever that means) and not used in 70 series. The heavy White lead is main 24v power from the battery/fusible link and goes to starter relay, fuse block no 1, alternator, head light washer motor (if you have one), power accessory box in the eng bay (not sure 60 series has this), tail light relay and perhaps head light relay. Not sure about the smaller red wire, on 70 series smaller red wires are for light circuits- dome light, rear fog light etc

You might want to see what works/doesn't work with that breaker removed from the circuit. It could be a bad breaker, but likely something further "down stream" that is no longer getting power with the breaker removed from the circuit. Start with lights... I think the head light and tail light relays are in the relay block in your above photo. on a 70 series they are the first column of relays in the relay block, tail light relay is round and above the square headlight control relay. Again, this is for a 70 series and yours may be different. I think you are getting there with finding that breaker!
 
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Well, it started raining, so I have to wait till it lets up....

BUT I have a strong hunch I know what it is. One would think big things like glow, starter, alternator, etc. But no. I believe and will test after the rain stops ...it is the friggin DOOR LOCK BUTTON. I believe it must have stuck in the actuated position. This could logically make sense because the door lock must have power even with the key is not in the ignition. It also makes sense, because it would have been one of the last things I touched before leaving the truck overnight.

I will report back. I'm going to be both mad and also very happy if this is the culprit. Mad because, well, its the stupid door lock actuator. Happy because, it isn't complicated to fix. When I have a second pair of hands (assuming this the case) I will have someone hold that button down while I check the current to see if it matches the drain I have been seeing.
-------

FOLLOW UP:
(Rain stopped.)

I removed the driver door panel, disconnected the 2 clips inside the door. Current drain is GONE. Then I hooked it back up and it is still gone. I suspect that in the process of removing the door panel, the sticky button got "released" so it is no longer actuated.

I have put everything I had disconnected back together except the door. The current drain is still gone.

I will do 2 things to verify this was the problem:
1. With everything re-assembled, and shunt removed, I will monitor voltage over the next few hours (before, the drop would be noticeable within a couple hours).
2. When I have a second pair of hands, I'll set back up to check current and have the other person hold the door lock button down to see if the drain matches what I was seeing.
 
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door lock actuator pulling 16 amps?
It seems like a lot, but there are 5 doors/actuators (rear hatch also gets actuated) that create a quick punch to lock or unlock. Perhaps similar to the windshield wipers which have a 20A fuse. The breaker for the door locks is 14A - I'm not sure if that one is for all 5 or if they are split somewhere. I suppose I could disconnect a couple of the doors and see if that splits the amount of current I'm seeing.

It will take a day or so of observation to see if things change - not saying this is 100% right yet.
 
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Confirmed. It is the door lock button sticking. If I hold it down I can force it to stick. I have replicated the problem and observed the 16amp draw.

I tried to upload a video of the ammeter before and after, but apparently I can't attach mp4 to the thread. Below is a link where I've attempted to share it. Hope it works.

 
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Good detective work. So the button/actuator doesn't always stick? Is the door lock breaker the one you disconnected in your photo? Is there also a fuse for the door locks and electric windows? Any short/fault that comes off of or down stream of one of those white wires has the potential to draw an extreme amount of current in a dead short situation.
 
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Good detective work. So the button/actuator doesn't always stick? Is the door lock breaker the one you disconnected in your photo? Is there also a fuse for the door locks and electric windows? Any short/fault that comes off of or down stream of one of those white wires has the potential to draw an extreme amount of current in a dead short situation.

If I push it down on the bottom edge of the button and hold it in place for a second, it will not spring back and hence that is when it is sticking. I have never known it to stick before now.

I don't see a fuse in the box for the lock or windows. There is probably a window fuse/breaker somewhere.

I don't believe there is a short. I think the actuators each draw some current when the button/switch is stuck on. I have now tested this....

I reconnected the wiring for the door lock switch, but I disconnected the individual actuators at the 2 front doors; that leaves 3 of the 5 actuators connected. I did the test again. This time I see a ~10 amp draw instead of ~16. If 3/5s (or 60%) of the actuators are engaged, one could theorize that they would pull about 60% of the 16amps, which would be 9.6 amps. This seems to be confirmed by what I saw. Each actuator pulls ~3 amps.

Blue circles in pics below are actuator connections and green is switch connection.

switch and driver actuator.jpg


passenger_actuator.jpg


10 amps.jpg
 
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