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1992 240 parasitic draw

sloopy

sloopy

2-digit whp
Joined
May 25, 2020
Location
North Texas
I just moved and neglected to plug my battery into a charger. It's sitting because the car doesn't have a/c, the shifter hole is wide open, and it's been around 100F for almost 2 months. It's a lithium battery (braille g30) and I discharged it down to 1.5V :^( The lithium charger has brought it back, but time will tell how much that reduced its capacity.

So I discovered I have a 200 mA draw with the key at 0. I've narrowed this down to the circuit going through fuse #8 on my 1992 240. From my documents, it looks like this serves power to: courtesy light, clock, trunk light, glove box light, locking relay, and power antenna. No lights are on, I unplugged the clock and still measured a 200 mA draw, and I don't have a power antenna. This leaves only the locking relay. When I put the fuse back in its spot, I heard a little pop which I sear sounded like the amplifier powering up, but I guess it could be the door lock actuators making this noise. Has anyone dealt with this before?
 
Central locking driver's door harness probably, the wiring disintegrates in the door and grounds. The central locking gets constant power for obvious reasons, I'd take the driver's door panel off and take a gander.
 
Luckily my drivers door panel is already off. Although I've repaired the harness myself, I'll unplug it and see if that fixes the draw.
 
I disconnected the driver door lock switch harness and it made no change. I also verified that the popping noise I hear when applying power to that circuit is coming from the rear right speaker. Very strange.
 
It looks like the amplifier receives constant power from fuse 8. And currently there is no radio in the car. There is a trigger routed to the radio which turns the amplifier on when it receives 12V. This trigger is surely not receiving 12V, but it's not grounded either. So maybe because the signal is floating, the amplifier is in a strange state and is drawing current all the time.
 
Floating grounds "and such" will drive you to madness.

My old 93 Ford van will take a healthy battery down in about a week when idle. I checked every fused circuit and listened to the "pop" when the ground cable touched the battery. Narrowed it down to 2 circuits, but never could locate it.

The solution I deemed acceptable: install a quick disconnect ground lead at the battery. Around $10 I recall. Now she can sit for weeks, and upon spinning that knob I've got full cranking power and normal ops. IMHO, the low hanging fruit for parasitic battery draw.
 
Thanks for the perspective. When I get home, I'm going to connect my radio harness which ties the amplifier trigger to the trigger which comes from the radio connector. Hopefully that will fix the issue.
 
You can also disable the central locking system by pulling the relay. The issue with the door harness insulation is not isolated to the drivers' door - it can occur in any of them.
 
sloopy said:
Thanks for the perspective. When I get home, I'm going to connect my radio harness which ties the amplifier trigger to the trigger which comes from the radio connector. Hopefully that will fix the issue.
Click to expand...
It did not fix the issue. I'm going to try unplugging the amplifier, the central locking relay, and whatever else until I figure out what's drawing the power.
 
It's not the amplifier. But I just discovered that the draw is only present when the drivers door is open. Not any other door. What's strange is that I removed the seat belt reminder chime relay, (Which I thought the drivers door switch is connected to) but the draw is still there.
 
I've heard 240's have problems with wiring in the floor console shorting to ground. There is that rear seat belt reminder lamp, seat belt buckle wiring, etc. Sometimes it gets pinched after console repairs.
 
Omg. I think that was it. I haven't had my floor console installed for years. I have noticed sometimes that the floor console's seatbelt reminder light's terminal would touch the metal bracket and the seatbelt reminder lights would turn on. I just pulled the lights away and over the carpet and the draw seems to be gone. I'm still confused why I was still seeing the draw with the seatbelt reminder chime relay unplugged.
 
Another relay that can draw sneaky power is the one for the interior light delay. That one will get energized with the door opening and if the relay fails it could keep drawing a bit of power. Not even lighting the interior light.
 
sloopy said:
Omg. I think that was it. I haven't had my floor console installed for years. I have noticed sometimes that the floor console's seatbelt reminder light's terminal would touch the metal bracket and the seatbelt reminder lights would turn on. I just pulled the lights away and over the carpet and the draw seems to be gone. I'm still confused why I was still seeing the draw with the seatbelt reminder chime relay unplugged.
Click to expand...
Its so rewarding to find stuff like that.
 
dl242gt said:
Another relay that can draw sneaky power is the one for the interior light delay. That one will get energized with the door opening and if the relay fails it could keep drawing a bit of power. Not even lighting the interior light.
Click to expand...
I just resolved my same problem on fuse #8. The door lock wires were grounding (exposed wires) fixed that still had the draw and drain every 2-3 days. Ended up being this little delay relay, removed it and all is good now.
 
There are two delay relays I know of. One for the interior light. Another for the rear defroster. Ooops, there is also a third for the a/c. All in that local center stack and above the driver legs area.
 
sloopy said:
is the delay relay not the same as the blue seatbelt reminder / chime relay?
Click to expand...
No. Open up the blue chime relay, snip off the speaker and throw it away, close it back up and install it where it belongs.
It's not confusing, it turns the reminder lights on and off
 
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