AMP light comes on.

Topic: AMP light comes on. (Read 2159 times) previous topic - next topic

AMP light comes on.

October 14, 2008, 08:23:18 PM

I have a 86 ls 5.0 coug. I was just going to work and the AMP light come on with I'm on the pedal but if I stop or at very low speeds it's off. So my assumption finds that this occurance happens under a load. Now I have a ideal what it may be, but wanted you guys to do some brain storming for me to see if we concur on the problem. I would love to tell you guys what I think is the problem, but I don't want to sway ideals, Thanks in advance.

AMP light comes on.

Reply #1 – October 15, 2008, 12:15:27 AM

Belt slipping.

AMP light comes on.

Reply #2 – October 15, 2008, 10:25:12 AM

May guess is a bad alt connector. You give it some gas and it move the pigtail just enough to make a bad connection. Trust me I had it happen to me on my 84 T/c. Either that or the pigtail has just gone south. I know that in those years they tell you to replace the Pigtail each time the alt is changed. The one that I sold at the part store used to come with the pigtail and voided the warranty if you didn't install a new pigtail.

AMP light comes on.

Reply #3 – October 15, 2008, 09:56:49 PM

if you can afford it,,
change the alt and the batt as a matched set.

AMP light comes on.

Reply #4 – October 16, 2008, 08:55:41 AM

Quote from: jcassity;239534

if you can afford it,,
change the alt and the batt as a matched set.

That is some good advice that is if you need them both. Yes they do have a lot to do with each other and sometimes the alt going out can suck the life out of a battery but before you replace either get them checked. That way you know what is what. Not I'm having this problem I replaced the alt and battery now its fixed! Yeah that might fix it but that does nothing to let you know what the problem is. Now if you have a fat stack of cash or money isn't any concern to you go for it.

AMP light comes on.

Reply #5 – October 16, 2008, 03:51:24 PM

Well my neg battery cable insulator is badly cracked and the underlying wires are exposed, but today I tried to go to work the battery was dead (no sound or clicking) I am gonna start simple and replace the neg battery cable and terminal. Here's my question lets say the neg cable is fubar and when I last ran it it was running off the alt could the battery run down or go dead with the vechile off with this sinerio? I have no acc to draw current like that. how could the battery go dead. Once I change the cable and terminal I will have the charging system check, thanks for the help.

AMP light comes on.

Reply #6 – October 16, 2008, 04:13:35 PM

I thought this was a contest to guess the answer that you already knew.

Do you have any tools like a meter and a test light to troubleshoot with?

AMP light comes on.

Reply #7 – October 16, 2008, 04:21:32 PM

Well that's what I'm assuming. Hey what's the length on the neg cable. it says 20inch, but 20inch isn't enough.

AMP light comes on.

Reply #8 – October 16, 2008, 10:25:03 PM

The shortest one I see listed is 24" but the also list a 48" so like that is much help

AMP light comes on.

Reply #9 – October 16, 2008, 10:32:13 PM

Quote from: softtouch;239441

Belt slipping.

You know,,
after reading the "symptom",,, i have to agree.

the symptom is the opposite and i read or assumed backwards.

light comes on with gas applied,, i remember looking at this as an odd symptom and the belt should have been my first guess as well. I suppose its possible to slip the belt and not hear it slip.

or..............................how about this one,,,,,,,,,,,,,,,
the belt is stretched out too long and therefore the tensioner is max right now as she sits,,, which still equals slipping belt.

+10 for softtouch

AMP light comes on.

Reply #10 – October 21, 2008, 02:42:57 AM

Too much charging can can light it up, as well as too little.

A few weeks ago my battery went dead overnight, with nothing left on or open (I checked carefully). I got a jump start and noticed the light came on when the engine was revved, but went out at idle. My handy-dandy pocket voltmeter showed almost 17 volts with the RPMs at 2000 or so.

Managed to get to work by turning the lights on (as usual) and cranking the heater fan up to full blast to absorb the excess power. Our shops's charging system tester showed the alt was putting out too much voltage even with a known good battery installed. The old battery wouldn't hold a charge any more, obviously cooked by the excess voltage. New battery and alternator, and no more problems.

AMP light comes on.

Reply #11 – October 21, 2008, 08:27:54 PM

You are right Master Baster. My alt was tested today and it put out 16volts and had to get a new battery. Now I don't have the money to fix it until this friday (payday). I was wondering what would make it drain overnight didn't understand it.

AMP light comes on.

Reply #12 – October 22, 2008, 12:14:08 AM

its not that its draining in this situation,, its actually not holding the charge inside due to the chemistry of the way batteries are able to store a charge. The potential to store energy will simply vanish without a trace,, kida like the way the fizz goes away on an open can of pop the longer it sits.

if you get the car started,, let it run for a while ,, then while its running,, pop the top off one of the battery caps.

look for small bubbles fizzing in there.,, those bubbles would be hydrogen gas,, just a few steps away from theremal run away.

what you have here is a situation where you would need to replace the alternator and battery together as a matched set.,, not to sound like im repeating things. If one or the other is bad,, either can effect the other by over charging or demanding too much current. Incorrectly done jump starts will also effect the alternator as well.

never connect to the good car last when jumping someone,, always make the last connection on the bad car, and make that last connection the ground. In most all instances, a small arch or spark will happen with the last connection is made and you want that to happen on the broken car. You also want the spark to occure on the ground terminal.

when removing cables, always disconnnect the bad car first and make that first cable you disconnect be the ground. The spark will happen again on the bad car and on the ground side.

AMP light comes on.

Reply #13 – October 22, 2008, 03:06:25 AM

My new battery is rated at 880 cca and when I had the charging system check the alt was loading the battery at 1100 cca and of course the volts of the alt was at 16 (this is with the new battery). I just can't believe the battery can go dead like that. Once the light came on I imediatly turn the car around. I only went 3miles b4 the turn around home. Once I got home I shut the car off with all lights and didn't turn it over until 6 days later and the battery was dead. Just can't wrap my brain around it. oh yeah the old battery was a maint batt. The new one is maint free. I bought the new batt 2day and have it outside the car right now until I replace the alt.

AMP light comes on.

Reply #14 – October 22, 2008, 02:22:09 PM

The voltage regulator controls the output voltage of the alternator.
Is this a 1G Alt with an external Reg?