AaronW

I need help diagnosing an electrical problem with my 1998 Limited 4Runner with the 3.4 V6 engine.

I have proudly owned my 4Runner since 2005 and when I bought it there were 103,000 miles on the odometer. Currently there are 231,000 miles on it and I have recently discovered an electrical issue.

January 2012 I went to start my truck and the battery was dead, so I took the easy, lazy, and expensive route to try and fix the problem by purchasing a new battery. After purchasing the battery I drove the 4Runner around for an afternoon to make sure that the battery was charged. Then I let the 4Runner sit for two days, and when I tried to start it back up there was nothing. Not even the horn worked.

Here is what I did next:
1. Trickle charged the battery.

2. Logged onto Yotatech and typed, "dead battery," into the search bar.

3. Read a number of posts and learned about using a test light.

4. Got a test light.
a. Unhooked the negative battery cable and clipped the test light onto the negative battery cable.
b. Put the test light probe onto the positive battery post to verify the test light worked...it did and the light lit up.
c. I asked my wife to hold the test light probe on the negative battery terminal...she agreed.
d. I pulled the fuses from the fuse box under the hood and in the dash. After I pulled each fuse I asked my wife if the light went on. The light never went on.

Here are my questions:
1. Did I do anything wrong while using the test light?

2. I have not checked the starter with the test light. How do I do that? I thought about waiting until the engine was cold and then feel the starter with my hand to "see" if the starter was warm to determine if the brushes were stuck and drawing a current.

3. Now what do I do?

Thank you for any help that you can provide.

4Crawler

iTrader: (3)

Better tool would be an inexpensive digital volt/ohm/amp meter (multi-meter). Set it up to measure current (amps) and hook that between a battery terminal and the cable that normally attaches there. Then you'll have a number to go by as far as the current drain and then do the fuse test you described, looking for the current to drop off.
- http://www.4crawler.com/4x4/CheapTri...oUseAnOhmMeter

You should be shooting for something less than 20 mA (0.020 amps), the lower the better. On my '85, I had a drain issue like that and in ~2 weeks, the battery would be too low to start. I had about a 0.050 amp drain and that was mainly due to an AM/FM radio that I had wired to constant (not switched) power. On that unit, even if you turned it "off", it was still on, to the tune of 50 mA. Rewiring it to switched power cut the current drain to a sub-10mA range.

For a 2-day discharge, you are looking at a pretty hefty current, maybe 1-2 amps (48-96 amp-hours). Could be a shorted diode in the alternator or a relay stuck on or a light bulb stuck on (like in a glove box or similar hidden place).

AaronW

4crawler,
Thank you for your reply. I have been to your sites and have found them very informative. I have actually been in touch with you before to ask some questions. I have a volt meter and will post the results.

AaronW

I have not yet used the voltage meter to test the fuses. However, I think I may have isolated where the electrical leak is occuring. I believe the electrical leak that is causing the battery to go dead has to do with the fog lights.

Here is why I believe this:
1. I unhooked the fog light relay and the battery has not gone dead since.

2. The fog light relay I had been using was not the original one and was from an Audi. I installed it because I wanted to use light bulbs that were brighter than the standard bulbs used. One of the brighter bulbs burnt out and I never replaced it nor did I replace the Audi relay.

3. In 2010 somone backed into the front of my 4Runner and tore the plastic piece underneath the front bumper. This may have crimped a fog light wire causing the short.

Ok, that is where I am at now and need to learn how to use the volt meter. I learn by reading and seeing so although the directions 4 Crawler has are great I still need to see how a volt meter is used.

RAD4Runner

AaronW, you're on the right track. I highly recommend you get familiar with the Factory Service Manual (link here). It will help you a lot down the road, and keep stealers from ripping us off.
4Crawler, Thanks a lot for sharing your knowledge and experience.

Hadmatt54

Relays come in many configurations, but basicaly a simple relay with one set of contacts has a stationary contact and a moveable contact that is attached to a plunger which moves inside of a coil, in other words an electromagnet. The relay is described by the moveable contact position when the relay is sitting on the shelf of your local auto parts store or in an electrical context when the coil is de-energized. The moveable contact can be either normally open or normally closed and thus the relay is described as a normally open or a normally closed relay. Also there is an ISO standard regarding size and pin configuration.
Now the dumb question:-
Did the Audi relay that you installed fit in the same mount (socket) as the original Toyota relay or did you wire in a new socket? I ask this question because if by chance you removed a normally open relay and replaced with a normally closed relay you will have a circuit through the new relay with the switch in the off position and a drain on your battery?

zyks623

I have done the test light thing. and got nothing. would i have gotten this result if it was a relay. or would the test have let me know that the relay is open. i have drained two batterys all ready. i got the ma from 13.5 to 6.5, is this a good amount to have. or am i still pulling to much.