Short in a relay???

optimacy · 04-07-07, 03:03 PM

Join Date: Apr 2007
Posts: 1

Short in a relay???
I have a 1991 FJ80 landcruiser with what I believe is a short somewhere. After leaving the car parked fully charged for a week, the battery is totally dead. Also, when I brought it in for alternator / batter diagnostics at Autozone, the machine said the test was "inconclusive" and to check the connection to the alternator. The alternator is a toyota OEM and is approximately 1 year old. The test showed a maximum of 30 amps at approximately 2000 RPM

There are 3 wires on the positive battery cable (main power cable to the starter and 2 smaller cables. I disconnected the bolt and removed the 3 wires. The main cable produces no sparks when striking it against the positive bolt. The smaller cable (wire) produces a tiny spark when striking. The larger cable produces a bigger spark when striking, and I also noticed a clicking sound (I believe coming somewhere deep inside the dash?).

One by one, I removed each fuse and relay (under the hood and in the front panel) and struck the wires against the post, and the same amount of sparks and the mysterious relay clicking resulted each time. It seems that removing all of the fuses and relays had no effect on isolating the circuit in question.

Has anyone experienced anything like this? Is this clicking relay normal? Is there another circuit I could be checking?

Thanks for your feedback - tom

Lka1988 · 04-07-07, 04:45 PM

Quote:

Originally Posted by optimacy

The test showed a maximum of 30 amps at approximately 2000 RPM

Just from that, I would say your alternator is bad. Most alternators put out at least twice that...

optimacy · 04-07-07, 04:52 PM

Thanks, I'll try disconnecting the alternator to see if the spark persists. I didn't at first think it was the alternator because the battery totally drains after sitting for a week (no running or starting). But I guess it could be the alternator, since I don't think there is a fuse or relay that disconnects it.

Lka1988 · 04-07-07, 10:35 PM

Just my $.02.

Colorado80 · 04-07-07, 10:46 PM

You know you can do all the hunting around manually or get a multimeter which will help you solve the problems. This way you can "see" which wires are live and which are drawing more/less current and what's going on internally rather than trying to locate shorts or disconnects with the naked eye.

Hope this helps.

jonheld · 04-08-07, 07:44 AM

This is an outside chance, but it is possible that your EFI relay is stuck closed. This would drain the battery in 2-3 days if the truck was not started. Ask me how I know that.

Next time you park, simply pull the relay. Pretty good kill switch as well

Beowulf · 04-08-07, 08:25 AM

optimacy,

Looking for sparks, little sparks, and bigger sparks is not the way to diagnose an electrical problem. You need the EWD and a multi-meter. JH has posted in the past that the EWD for your year is on his web site. Or, you can use Nate's automated download process to get all of the manuals (including the EWD) for your truck with a $10 subscription to TIS.

-B-

optimacy · 04-08-07, 12:33 PM

Sorry to be such a newbie but EWD? Thanks that site looks interesting and I'll take a look. I'll also try to remove the EFI relay to see if that is causing the short

Last night I cleaned up all the electrical terminals on the alternator and battery and tightened everything up and brought it back to autozone for a test this morning - now it said something about "Invalid diode"? But the strange thing is the guy this time put the passive clip of the tester on the negative side, and I could swear last time he put it on the positive side (the tester has 3 attachments, 2 attach to the terminals and 1 attaches passively like a loop over one side). DId he run the test wrong?

By TSM I believe you mean toyota service manuals - yes I did purchase a subscription awhile ago and downloaded everything I thought I could use. I see looking back there is a nice one about the electrical system. I just figured one of the fuses or relays would give me a general direction to look.

I do have a multimeter, so I'll try some of the tests this manual specifies.

Also, I don't know if this is a short or not - the problem is, this thing is not bad enough to blow a fuse or melt wires, but it is enough to kill the battery after 1 week of non-use. Since I only drive my LC once every 8 days (and then for a 6 day stretch) it is more noticeable I guess.

But thanks again for all the feedback - I'll try everything mentioned here and report back my findings.

Tom

Beowulf · 04-08-07, 10:08 PM

EWD = Electronic Wiring Diagram.
FSM = Factory Service Manual.
TIS = Toyota Techinfo Site (I think that is what it stands for.)

-B-

mobi-arc · 04-09-07, 12:34 PM

If you have the alternator out of the truck, do yourself a HUGE favor and take to a proper alternator/starter rebuilding facility....every town has at least one. The alternator is the easiest thing to fix, especially since it's out of the truck. If the alterntor tests okay with respect to diode leakage, rotor resistance, etc.., and your sure your battery drain is alternator related, it's down to wiring.