ammeter ticking

95blktahoe · February 19, 2006

i have a 1995 chevy tahoe 2dr w/ 160k miles on it. there is an alarm/autostart and a stereo system in it. over the past year i have had a problem with killing batteries. i replaced the factory battery twice, and each one died after about six months.

then i replaced it with an optima red top. it worked better, but was still hard to turn over after sitting for a day or two. so i replaced the alternator. it was from autozone, a 105a heavy duty duralast. this certainly gave the truck a bit more pep, but the same thing keeps happening with starting it. the other symptom that i notice is a ticking of the ammeter, back and forth from about 11v to 13.8 or 14v. this happens when i put the blinker or flashers on. when i put the headlights on, reverse lights on, defroster on etc, the ammeter will go down to 11v. this should NOT take 3v out of the system, it must be grounding out somewhere. i know that it is not the wires for the amps, b/c i took them off the battery (at the battery) to isolate the problem. the other thing that happens sometimes is that the headlights won't work (but parking will) and the switch gets warm/hot to the touch. this morning i blew the ignition fuse. i think that it has to be a live wire (b/c it drains the batt when the car is off) that is somehow grounding out between the dash/steering column/wiring harness... any ideas?

i've got 160k on the truck and she's been good to me. i'd like to keep her on the road. thanks!

Jayock · February 19, 2006

Ok, so I assume you are talking about a Voltmeter, and not an ammeter???

Sorry, im an electrical engineer, so im probably a bit picky, but an ammeter measures current not voltage, so im a bit confused.

Secondly, are you talking about a voltmeter that you own and are using to measure while the car is stopped, or the one built in to the gauge cluster?

95blktahoe · February 19, 2006

Ok, so I assume you are talking about a Voltmeter, and not an ammeter???
Sorry, im an electrical engineer, so im probably a bit picky, but an ammeter measures current not voltage, so im a bit confused.

Secondly, are you talking about a voltmeter that you own and are using to measure while the car is stopped, or the one built in to the gauge cluster?

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my apologies, the voltmeter. and yes, the one in the guage cluster.

Jayock · February 19, 2006

Those are not typically connected directly to the battery, but to another circuit. Its is very common for those to be connected to a circuit shared by some of the other accessories. This might be why you see the voltage drop on that gauge. Try a stand alone voltmeter if you can get your hands on one directly from the battery.

Also, how many watts is your stereo system pulling? If its high enough, you should install a capacitor inline with the amp. This will help with sudden spikes in power needed by the subs. A nice 0.5 farrad, or even a 1.0 farrad cap if you are running a big system.

mmmikkke · February 19, 2006

You should also check for AC (alternating current) when checking your truck with a voltmeter. Try getting a cigarette lighter adaptor, and connect the wires from that to a volt meter. Then drive with the meter running. Verify that the DC voltmeter gage reading is accurate, and then switch the meter to AC and see how much AC voltage is getting through to your cigarette lighter. If it's more than a few millivolts, you might have an alternator diode failing, or your alternator might be toast.

95blktahoe · February 19, 2006

Those are not typically connected directly to the battery, but to another circuit. Its is very common for those to be connected to a circuit shared by some of the other accessories. This might be why you see the voltage drop on that gauge. Try a stand alone voltmeter if you can get your hands on one directly from the battery.

Also, how many watts is your stereo system pulling? If its high enough, you should install a capacitor inline with the amp. This will help with sudden spikes in power needed by the subs. A nice 0.5 farrad, or even a 1.0 farrad cap if you are running a big system.

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stereo system is pulling no more than 65 watts, that's what's fused on the amps, but i've eliminated this as the culprit b/c i totally disconnected the leads from the amps to the battery (at the battery), and the ticking still occured.

i guess that the voltmeter is telling me that there is a problem somewhere in the circuit that it is attached to.

95blktahoe · February 19, 2006

You should also check for AC (alternating current) when checking your truck with a voltmeter. Try getting a cigarette lighter adaptor, and connect the wires from that to a volt meter. Then drive with the meter running. Verify that the DC voltmeter gage reading is accurate, and then switch the meter to AC and see how much AC voltage is getting through to your cigarette lighter. If it's more than a few millivolts, you might have an alternator diode failing, or your alternator might be toast.

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i'll check on that. but i think that the alt is good, this was happening with the old one as well. find it to be a real big coincidence to have 2 bad alts back to back (but yes, possible)

Jayock · February 23, 2006

Those are not typically connected directly to the battery, but to another circuit. Its is very common for those to be connected to a circuit shared by some of the other accessories. This might be why you see the voltage drop on that gauge. Try a stand alone voltmeter if you can get your hands on one directly from the battery.

Also, how many watts is your stereo system pulling? If its high enough, you should install a capacitor inline with the amp. This will help with sudden spikes in power needed by the subs. A nice 0.5 farrad, or even a 1.0 farrad cap if you are running a big system.

<{POST_SNAPBACK}>

stereo system is pulling no more than 65 watts, that's what's fused on the amps, but i've eliminated this as the culprit b/c i totally disconnected the leads from the amps to the battery (at the battery), and the ticking still occured.

i guess that the voltmeter is telling me that there is a problem somewhere in the circuit that it is attached to.

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Fuses are usually in AMPS, not WATTS. 65 on a fuse means 65 AMPS. Which is anywhere from approx 700-1000 watts, depending on voltage. Now if you calculated the wattage already from the current, then ignore what I just said.

But regardless. the only true way to find out if your electrical system is f*ckin up is to test it directly, in a non-fused standalone circuit.

Also, the next culprit down the line from the alt. should be your regulator/rectifier. They can cause problems similar to this when they are on their way out.

asepgrad98 · February 23, 2006

there is an alarm/autostart and a stereo system in it

there's your problem right there.

When the truck is off there is a parasitic drain on your battery. You can change alternators and batterys from now until the truck body rusts off but until you fix that drain on the battery you will still have problems.