Amp light stays on. Please help

[89sspcoupe]

Hey guys,

I just bought an 89 ssp couple with 130k miles on it. I've replaced the battery, the alternator, and the starting solenoid among other things. I'm mentioning these three because I thought they go hand in hand with my issue. My amp light stays on from start up and never turns off. I notice my car takes a while to start up when cold. Starter sounds good it just seems like there's a lack of power during start up. I don't know if these two are related but I figured I'd mention it in case they were. I'm wondering if this is a wiring issue or what. What does the amp light mean anyway? The amp light was on before I changed all the parts so I know its not the parts.

 

[ViperPunk]

maybe the car is throwing a code? have you tried to pull any yet

 

[Kdubslugga]

Amp light is on but the car is charging? Sounds to me like you may have an issue with a single wire coming out of the alternator. Heres a good diagram

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Wiggle some stuff around see if you can get that light to go off even for a second.

The amp light is there to notify you when your charging system is below normal. If you have a problem with that 14 guage single wire anywhere, its gonna toss that light on regardless. I see you have an SSP car so you may have a slightly different alt. Is your alt a 130 amp? If so youd be looking at the 1 wire plug in on the alternator.

 

[89sspcoupe]

I just put in a brand new PA performance alternator pushing 130amps, a yellow top optima battery and an msd blaster coil. The amp light was on before with the old alternator and with the new one. Haven't tried to pull any codes. Don't have any of the equipment. Should I take it to a mechanic to hook up to find a code?

On my car I noticed I have a seperate regulator for the alternator on the right side of engine bay. Two wires from that hooked up to the top of old alternator. I have wires all over the place. The engine is a bit of a rats nest right now. I'm not sure if some of the wiring was from the old cop sirens or what. The car was undercover so I didn't have any extra lights maybe some strobes but thats it.

Also, underneath the steering column is a little black box that clicks every 20 seconds or so. When it clicks the volt meter goes down a notch and when it unclicks a few seconds later the meter goes back up. I've unplugged the harness that goes into in and the clicking stopped but the volt meter still shows it drawing.

Amp light is on but the car is charging? Sounds to me like you may have an issue with a single wire coming out of the alternator. Heres a good diagram

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Wiggle some stuff around see if you can get that light to go off even for a second.

The amp light is there to notify you when your charging system is below normal. If you have a problem with that 14 guage single wire anywhere, its gonna toss that light on regardless. I see you have an SSP car so you may have a slightly different alt. Is your alt a 130 amp? If so youd be looking at the 1 wire plug in on the alternator.

 

[Kdubslugga]

But mechanically there is nothing wrong with the car? You can drive it come home shut it off it will fire right back up? If so scanning it wont tell you a thing.

 

[89sspcoupe]

But mechanically there is nothing wrong with the car? You can drive it come home shut it off it will fire right back up? If so scanning it wont tell you a thing.

Yeah it drives fine. I take it out a few times a week and it drives and starts up every time. The start up does sound week though but someone told me because my cam is aggressive that I may always have that issue.

 

[89sspcoupe]

I figured it out guys. The car has an external voltage regualtor for the old alternator on the passenger side of the engine bay at the top. It's a small metal box with a harness plugged into it. I unplugged it and bingo amp light is off. So now I can get rid of that ugly box from the engine bay and clean up some of the wiring. It's a bit of a rats nest right now.

 

[Kdubslugga]

Awesome dude, good job!

 

[YawnY]

You should replace that voltage regulator instead of just removing it. Might clean up some wiring but now your alt. is putting out full 14.6 volts (give or take) and over charging your battery and electrical system.

 

[CandyRed 88]

I figured it out guys. The car has an external voltage regualtor for the old alternator on the passenger side of the engine bay at the top. It's a small metal box with a harness plugged into it. I unplugged it and bingo amp light is off. So now I can get rid of that ugly box from the engine bay and clean up some of the wiring. It's a bit of a rats nest right now.

Is this the box you're talking about? I'm having the same issue.

 

[Mustang5L5]

Is this the box you're talking about? I'm having the same issue.

that is the WOT (wide open throttle) relay.