hello,
I have a 97 4runner with a parasitic battery drain.I replaced the battery,and did a battery check with a test light and negative cable and the drain is coming from the dome fuse, but none of the lights are staying on when the key is turned off. the battery will go dead in about 10-12 hours but will charge right back up when driven.....please help I don't know where else to look...any help would be great...thanks

Hello and welcome to the forum!

The readings below (all measured at the battery) in the first table (ignore the second table) are typical values for a 2000 4Runner.. Thought these readings and the following info might be helpful, depending the specific features mentioned below that your '97 has..



If your '97 has the security system and power windows (functions performed by the so called "body ECU", and wireless key fobs which requires the so called "back door ECU/radio" (because that's where it is located) I would guess your normal drain readings would be similar to mine. Both of the above mentioned computers run all the time. The Toyota service manual states parasitic current with everything off, doors closed should be under 50ma.

In the readings above, as noted all dome lights were turned off, but note how the readings change, when doors are opened. This is due to body ECU coming out of sleep mode into operational mode..

The body ECU in operational mode draws enough power to run the battery down, if for example as I did, switched off all dome lights and left the doors open overnight (to dry out the carpeting that got a bit wet).. But if your '97 doesn't have these systems, we can move on to the items below.....

I'd suggest you buy a Volt-Ohm-Meter (that can measure small current loads, if you don't have one, and make the exact drain measurements as that may be helpful in isolating..

Other than the above, the clock, and off course, the dome lights themselves, the door ajar light in the instrument panel, and if you have them, vanity lights in the sun visors are pretty much it for the loads on the dome fuse circuit, per the 2000 model factory service manual..

Lastly have there been any wiring modifications or accessory electrical gear put in your vehicle?

Please post back here which of the items mentioned above that your vehicle has, or does have.. That will be helpful in deciding what to look at next..

hello and thanks for responding,
It's the limeted edition so I believe it has all power options. It has factory security system, power sun roof,I had a aftermarket stereo installed, but they said it was'nt drawning power when off...I also forgot to mention when I pull the dome fuse the radio goes out.

I'd suspect the radio wiring. Most aftermarket (and most OEM) radios have a batt+ lead (to retain station memory settings) and an ignition+ lead (to power the radio when the key is on or in ACC). If your radio dies when the dome fuse is pulled, I'll bet the ignition+ lead is wired into the dome circuit instead of a key-switched circuit.

It shouldn't pull current if you turn the radio off, but might... Good luck.

I think Whizkidder is on the something..

When you say the radio dies, do you mean it doesn't play at all, or does the radio lose its station presets (memory) when the dome fuse is removed?

the radio doesn't play at all.when stereo was install it was installed with a adapter kit that connected right into factory wiring no splicing. I also removed the stereo and checked all the wires for "hot" and the only one that was hot in the harness was the memory hot wire like it was suspose to be.so how could the stereo be wired to dome fuse I don't know. the only thing i can think of would be the power antenia maybe. the radio also goes off when I pull the acc fuse.but would that be enough to drain a battery in 10 hours? also my brother in law owns the car stereo shop where I had it installed and they took it out checked the same things i did.

If there is a second aftermarket accessory tied to the dome circuit you probably need to investigate this connection..


You guess is correct! I missed this connection looking through the schematics the first time.. There is an "antenna control relay" that is powered from the dome circuit as shown below..

yes and no..

A correctly installed radio should be powered by the accessory fuse, but that load is fed through the ignition switch, which of course is turned off, when the switch the ignition off, so any loads through that circuit should not pull the battery down..

Here is the schematic for the above.....



Ignition switch is fed by the AM1 and AM2 fuses... accessory fuse is down stream of the ignition switch and of course, no power supplied to it when the ignition is off.




Does the power antenna still go up and down EXACTLY as it did before the stereo installation? Anything holding up the antenna control lead might be causing the antenna control relay to still be drawing power after the vehicle is shut off.. I'd look in this area closely..

Also, many times what Toyota calls a "relay" in the schematics is in fact an electronic circuit, which can be damaged.. Maybe this thing is constantly drawing power through the dome circuit, which it should not do..

thanks so much for your help I'll try and look at the antenna a little closer....again thanks alot.

I started looking at the power antenna and found this...I pulled the dome fuse and turn the key to acc and I heard a clicking noise on and off (relay right) and then a motor start and stop again (power antenna motor?) so now I need to know where the relay is.....thanks again

Here is a link to a pic of the locations of the various 4Runner control units.. It's a pretty big pic so I linked to it rather than put it directly in this post.

Follow the arrow from the wording in the lower left hand corner...