xfactor203

Appreciate some help from you clever folks on this one. . . (94 4runner)

Trailer brake lights quit working. Traced it to 5-to-4-wire trailer converter in panel behind driver's side tail light. Brake light current was going TO converter, but nothing coming out. Swapped in a new converter, hooked it up the same way EXCEPT for some reason right turn wire was spliced-in on trailer side of converter before. I hooked up the wire properly (on truck side) when I put the new converter in. Everything works great. Joy. Drive around for a couple days with a trailer. Life is good.

Monday morning truck is a no start when I try to leave for work. Solenoid clicks, that's all. At this point I assume I messed up the wiring somewhere and the battery drained overnight. Jump it with my wife's car and everything (lights, signals, etc.) works great when jumper cables are attached. Disconnect cables and truck stalls when I turn on the headlights - won't crank, dash lights dim. Jump it again and unhook. This time headlights work but truck dies when I hit the right turn signal (not the left) - again, no crank, dim dash, etc. Take 3: this time lights and signals work but the truck dies when I hit the rear window switch. Take 4: leave it hooked to the jump vehicle for about 20 minutes this time. Now everything works great / truck cranks hard, starts no problem. I had 14.5 v across the battery terminals when hooked up to my wife's car and 12.8 v unhooked when everything was failing, then 14.5 v unhooked later on when everything was working properly.

Next morning: DEAD. Put it on a battery charger this time. Took a full charge according to the charger, but still dead. Door buzzer sounds normal when the key is in the off or acc position, but gets quiet when I turn it to run or turn on the headlights. Lights don't work, radio flickers. Door lights come on but are dim. Voltmeter on dash shows maybe 4 volts. I now get 12.8 v across the terminals (truck is not running), which drops to 4-8 v when I turn the key to accessory or turn on lights. There does NOT seem to be a drain on the battery. I only get about 0.015 amps between the neg battery terminal and unhooked neg clamp when everything is shut off, which I figure is probably the clock. I DID try hooking up the trailer light converter the way it was hooked up before in the midst of all this and it did not fix anything. I also tried pulling the fuses for brake lights, tail lights, and turn signals, which did not fix anything either.

So any ideas? Why would it start from a jump but not a charger? The battery charged up fast on the charger, leading me to think it either didn't really charge, or that it wasn't really dead in the first place. Am I right to be chasing the trailer wiring, or could it be something unrelated?

scope103

Sounds like you have all the symptoms of an expired battery. In other words, won't hold a charge. You need to check it on a carbon-pile battery tester, like this: http://www.harborfreight.com/100-amp...9888-9191.html

But no need to buy one; almost any auto parts store has one and they are more than happy to test it for "free."

RJR

Either an expired battery (not unlikely) or a corroded connection between the battery terminal and the cables. If you got the 4-8V on the battery itself when you turn something on, it's almost for sure the battery. If you were measuring on the cable clamps, go back and measure on the physical battery terminals. If there's a big difference, you've got connection problems.

xfactor203

I haven't written off a bad battery, but it seems a little unlikely. First of all, this came on suddenly. No slow cranking, dead batteries after sitting for a while, or other symptoms of a bad battery. The truck is driven infrequently, and always cranks hard when I start it after sitting for a week or so. Second, the battery is barely a year old, and it's an expensive one that's never been run down.

millball

xfactor203

OK, OK. I'll have the battery tested (hey, it's still under warranty!). It still seems odd that it would crap out all of a sudden like that. Also weird that it would take a charge off another car but not off a charger.

RJR

Your DVM will tell you everything you need to know to find out where the real problem is. Just to amplify on my earlier suggestion.

1) With the engine stopped and everything turned off, measure the battery voltage on the battery terminals, not the cable clamps. Should be about 12.5 volts. If it's less than 12, you have a discharged/bad battery. Go to step 4
2) Now turn on the headlamps. Measure the battery again. If the voltage drops below 12, you have a discharged/bad battery. Go to step 4
3) If the voltage stays above 12, measure the voltage across the cable clamps (ground cable to positive cable). If it is less than 11.5 volts, you have a bad connection to the battery. Could be the ground terminal or the positive terminal. To find out which, measure between the battery terminal and the attached cable clamp at both terminals. If either reads more than 100mV or so, pull the cable and clean up the connection.

4) To test if the battery is bad vs your alternator not doing its job, jump the vehicle and get it started. Let it run for 10 minutes and then measure the voltage on the battery terminals with the engine running at a moderately fast idle. If it's above 13.5 volts your alternator is doing its job and the problem is likely a defective battery. Get it load tested at Auto Zone to be sure. If the voltage is below 13V, the problem is likely with the alternator.

Keep in mind that, when you jump a vehicle, the assist vehicle is typically supplying power to the battery cables of the assisted vehicle, not to the battery itself. So the jump will start the engine regardless of connection quality to the onboard battery terminals. When you remove the jumper cables, the poor terminal connection quality prevents the onboard battery from supplying the necessary starting current.

millball

VOMs' are handy in a hundred ways, but are no substitute for a battery load tester.
Many times a battery can be charged to show good voltage, but will have no working capacity.
The volt meters on most of our Toyotas are useful as load testers.
The level that the dash voltmeter drops to while cranking, is a good measure of the batterys' condition, if the battery is being properly charged by the vehicles electrical system, or if the battery has been recently charged with a charger.

xfactor203

OK. Thanks for the detail. I'll re-test when I get home later. I sort of wonder if the alternator might be slowly failing. I've had some intermittent accessory noise for a while now that could be alternator crapping out. Also seems suspicious to me that I was only getting 12.8 across the terminals (with the truck running) when everything was going south last night, but getting 14.5 when everything suddenly worked great again.

So, everyone seems to think this is coincidental with the trailer wiring escapade, huh?

RJR

Precisely, which is why I specified testing the voltage with the headlamps on. The 10 amps or so of headlight current will smoke out most weak batteries and/or poor connections. If not, as you pointed out, turning the key to START activates the built-in battery load tester (aka the starter). Make those same measurements with the key turned to start, and you'll know exactly where the weak spots are in your circuit.

millball

Could be that your alternator is charging intermittantly.
One reason could be that the slipring brushes are worn short.

xfactor203

Thanks for all the insight. I'll report back once I have a chance to take another stab at this.

xfactor203

RJR was the winner:

Cleaned up the + terminal and it fired right up. Here's hoping it lasts. . .

dropzone

iTrader: (6)

Good deal..

Terrys87

iTrader: (1)

Good to hear you got it fixed. I see alot of problems from stereo wires and trailer wires. Here is a kit I use for my trucks. Solves alot of problems.
PN# 43315.