Truck Won't Start....Flaky alarm system?

So my truck won't start since Monday. I turned the key that morning and I just heard a "thunk" and nothing. My dash lights went all crazy flickering and dimming and my gauges were jiggling around like there was a short or bad ground. I noticed the little red light for the alarm system was still blinking too. I clicked unlocked a couple times to make it go off and it finally does. I check the battery, 12.6 volts, good. Checked all fuses, good. Checked ground from battery post to frame and battery to body, good. Did a voltage drop test (turned on radio, blower fan, parking lights, headlights wouldn't turn on though which was odd) then checked from neg battery post to frame then to engine and voltage was less than half a volt so that was good. So now I'm stuck.

When I turn the key to On, the dash lights light up than slowly dim and then flicker and I hear a buzzing noise coming from the dash, I try to start the truck and no click or no noise. I attach a jump pack and truck starts right away. So I charge my battery overnight (just to be sure it's not low). And tried it again in the morning, and it still won't start. Same symptoms, flickering dash lights, gauge needles bouncing/jittery.

Another thing I noticed is that the unlock/lock beep sounds like half a beep instead of a solid beep (if that makes sense). And the door unlocks but the red blinking alarm light (next to steering wheel) doesn't go off like it should. Could the alarm system be acting up and disabling the ignition somehow? A bad ground somewhere I need to check? Odd how it will only start with a jump. I'll go get my battery tested at the auto parts store just to completely rule that out for sure. But what else am I missing or need to check?

 

Sounds like corroded cables. Did you do a voltage drop test from the positive battery post to the positive cable?

 

I cleaned it good, and checked resistance and checked good, but have not done the voltage drop test. I'll get that done soon as I get home from work. Thanks for the tip.

 

If the truck won't start, but starts with a jump, there's really only 2 things it can be. Junk battery or corroded cables. When you put the jump pack on, you're clamping on the cables and bypassing the connection between the cables and the battery.

 

Replace the battery. That’s the problem

 

Not the scientific way, but you could put a volt meter on the battery.
Try to crank the truck, and see what the voltage drops to.
It is quick and simple, it doesn’t tell you the exact issue.
But it gets you on the right path.

 

Here's a link for the alarm user manual:
https://drive.google.com/file/d/0B7jNp9uZ59w3NGYtS3RJbXVRV1U/view?usp=sharing

I did a write up on removing the GST alarm as well, here:
https://www.tacomaworld.com/threads...-removal-that-little-red-devil-button.675634/

This fixed my issue, as well as replacing a broken earth wire.

 

Tested battery voltage drop and that was terrible. 12.6 static voltage and 8.3v loaded (hi beam lights, radio, blower, wipers, and 4 way) . So drove to the auto parts stores to have battery tested and yup, battery was toast. Bought a new Deka battery size 27F, 840CCA, everything is back to normal now and truck starts up great. Glad it was not the alarm or a ground wire issue in the harness. Did not want to go down that rabbit hole in this summer heat. So relieved it was just the battery. Thanks for all the tips!

 

Just a reminder to those who don't know....heat kills batteries faster than the cold. So do whatever you can to keep your battery cool after wheeling or towing at slow speeds for extended times. If you've been working your truck hard in the summer heat, go park in the shade and pop that hood wide open to let it cool. I killed my battery by crawling in the summer heat up some trails with the ac on blast for miles and miles under the summer sun then came home and parked it in my hot driveway. It was probably over 100 degrees that day and no wind or trees around and I was crawling at slow speeds with high rpm. Perfect formula for excessive heat under the hood. I bet all that heat from the engine probably overheated the battery. I kept track of coolant temp, trans fluid temps, and all other temps in Torque pro, and nothing was alarming, but I didn't think about the battery. Should've took some breaks and parked under some shade with the hood open to cool the battery down. Also should've parked in the shade when I got home with my hood open to let the engine and battery cool. Hindsight's 20/20 I guess.

 

damn, I’m good!!!

 

I don't replace anything without testing it. Had I replaced it and it wasn't the problem, you can't return the battery. And a 27F battery ain't cheap.