No voltage on gauge, 11.5 volts on scan tool, whats wrong?
07-25-2009, 08:40 PM
#1
No voltage on gauge, 11.5 volts on scan tool, whats wrong? Been doing some work on the 98 TA, all was well the other day. Had nearly 14 volts running, gauge worked in dash, etc. Today, I fire it up to wash it and have no movement at all on the volt gauge (like the cars off), the scanmaster reads 11.5 volts max, car runs but I think its just running off the battery. It did this before I washed it, mind you, so water isn't the issue.
The other weird thing is my security light is blinking in the dash. Never noticed that before. Like I said, the car runs. I drove it and the longer I drove the lower the volts got on the scantool, hence why I think its just running off the battery. Car has barely any electrical draw, basically a race car.
Checked the fuses and other obvious stuff, can't find a problem? Thought maybe the alternator went bad, but shouldn't I still read battery voltage on the gauge?
Thanks for any help!
The other weird thing is my security light is blinking in the dash. Never noticed that before. Like I said, the car runs. I drove it and the longer I drove the lower the volts got on the scantool, hence why I think its just running off the battery. Car has barely any electrical draw, basically a race car.
Checked the fuses and other obvious stuff, can't find a problem? Thought maybe the alternator went bad, but shouldn't I still read battery voltage on the gauge?
Thanks for any help!
07-26-2009, 01:22 PM
#3
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check your alternator; possible voltage regulator issue.
It's odd that your dash voltage is not reading. Maybe you have a short to ground. I think tracing the power lines with a multimeter is a great idea.
if you have questions about how to check for voltage drops...
http://www.aa1car.com/library/voltage_drop_testing.htm
good luck
It's odd that your dash voltage is not reading. Maybe you have a short to ground. I think tracing the power lines with a multimeter is a great idea.
if you have questions about how to check for voltage drops...
http://www.aa1car.com/library/voltage_drop_testing.htm
good luck
07-26-2009, 09:54 PM
#5
If I jump power to the exciter wire on the alternator it starts charging, so apparently either the pcm/wire/gauge cluster has crapped out. I am going to run a new wire with resistor from an ign source I guess, can't see any other way to fix it?
07-26-2009, 10:11 PM
#6
i am having a similar problem. with key on engine off i am getting over 9 volts to the signal wire. this is the second alternator in two weeks on the car and they both have less than 5 hours on them. apparently this wire only needs 5v or less?
anyone have a schematic on where the reisistor is for the alternator signal wire?
anyone have a schematic on where the reisistor is for the alternator signal wire?
07-26-2009, 10:39 PM
#7
I meter'd a buddies f body today and got 10.4 volts on that wire, I thought it was supposed to be 5 but that didn't work.
From what I've read, you need a 12V ign source with a 470 ohm 1/2 watt resistor inline. I think my gauge cluster went bad or something, causing this issue.
From what I've read, you need a 12V ign source with a 470 ohm 1/2 watt resistor inline. I think my gauge cluster went bad or something, causing this issue.
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07-26-2009, 11:05 PM
#8
I meter'd a buddies f body today and got 10.4 volts on that wire, I thought it was supposed to be 5 but that didn't work.
From what I've read, you need a 12V ign source with a 470 ohm 1/2 watt resistor inline. I think my gauge cluster went bad or something, causing this issue.
From what I've read, you need a 12V ign source with a 470 ohm 1/2 watt resistor inline. I think my gauge cluster went bad or something, causing this issue.
this is what i have gathered in the search as well. most of the threads say that exicter wire should only see 5v or less and if it sees more than that the alternator will cook. both alternators i have taken in have had the welds on the rotor pop.
i am going to do one of two things. tomorrrow i am going to ask the guy that builds my alternators if he can put a self-exciter on it for me and see if that eliminates the problem first.....if he can't then i am going to run a separate 12v trigger(ignition wire) and wire the reisistor in line.
07-27-2009, 08:07 PM
#10
well you had better luck than i did. i tried three different resistors and all of them were garbage.
i ended up getting a self exciter for it and soldered it in. works like a champ at 14.4 all day now. 25 bucks and i'm done.
07-27-2009, 10:06 PM
#11
Got a pic or link? Wouldn't mind seeing that. I just got a resistor like everyone mentioned here (the hybrid/swap section was a good place to search) 470 ohm 1/2 watt and put it inline with an ign 12+ source to the red wire on the alternator.
07-27-2009, 10:25 PM
#12
i dont have a pic or a link. i went to a local place that does all the work on electric motors for my company. they showed it to me before they sold it to me. it looked exactly like the regulator that was in there except the guy told me it was a self exciter and didnt need a signal. i asked him several times as it looked the same as the one i had replaced by the "other" company(earlier in the day) and he assured me it was indeed a self exciter.
10 mins later i installed it and it was good to go. it is now a true "one wire alternator."
i tried the 470ohm 1/2 watt resistor and it wasn't droppping the voltage on the signal wire. i even tried running a separate 12v source wire and it didnt drop it on that either. i dont know what the hell was happening but it wasn't working like a resistor was suppose to.lol.
