electrical problem

Lightspeed · 06-22-2003, 12:48 PM

my original voltmeter doesnt work in my mustang so i decided to put a new one in, i had been having problems with electrical stuff ever since i had the car, well when i put the meter in the needle just starting jumping...it wouldnt ever stay in a steady spot...did i hook it up wrong or what kind of problem could cause this?

PKRWUD · 06-22-2003, 04:21 PM

Where did you hook it up to? Were you opening and closing the door, or turning on the radio, etc?

Lightspeed · 06-22-2003, 07:30 PM

well first i hooked it up where my radio used to be and it read 12 volts without the key on...then it read 14 when i turned on the car...then i hooked it up to the wires that ran my gas gauge, oil pressure and temperature gauge and on all of those it wouldnt hold a steady pulse...where would the propper spot be to hook it up?

Lightspeed · 06-22-2003, 07:33 PM

sorry i meant it read 12 volts with the key off

PKRWUD · 06-24-2003, 08:08 AM

You want to attach it to a hot lead from the battery, and a good ground. Don't attach any other wires directly to that circuit, because if wired in series, it will include their direct load in it's measurement, whereas what you are trying to read is the total overall load.

Take care,
~Chris

Rev · 06-24-2003, 07:10 PM

Doesn't he need to hook up to the "on" post or "accessory" post of the ignition switch? That way the volt meter won't read at all untill the ignition switch is activated either in the acc. position or the on position.

Rev

PKRWUD · 06-24-2003, 09:50 PM

If he wants to. I run mine off the battery. I don't want to have to rely on the ignition switch working to get a reading. Besides, wiring it through the accessory terminal won't give you an accurate reading of the battery, because other demands will be on when the switch is in that position. If you want to read true battery voltage, it needs to come from the battery itself.

Take care,
~Chris

gofastmercury · 06-24-2003, 10:23 PM

Can you leave hooked up like this for long periods of time? How many amps(mili?) will this pull?

PKRWUD · 06-26-2003, 03:37 AM

I guess it depends on how fancy your voltmeter is.

If it's just a regular old dial gauge, the amount of energy it takes to hold that needle in place is a lot less than it takes to preserve your radio stations. I've left my truck by itself without being started for a couple months at a time, and it still started fine on it's own. Of course, I've left my headlights on before to, and had to jump myself from my auxilary battery, but that's another story.

Take care,
~Chris

Rev · 06-26-2003, 02:18 PM

I think the hot lead at my ignition switch reads the same voltage as at the + battery terminal. Of course mine is a simple, old car with few electrical accessories. The truth is that I still use my old stock amp meter, LOL. I only use the hand held multi-meter voltage meter is if I'm trouble shooting a problem.

Rev

Jeff65 · 06-30-2003, 02:11 PM

A voltmeter is added to the accessory bus. On '65-'67 Mustangs this is a screw in the center of the ignition switch. On '68 and later, I'd have to refer to schematic wiring for the model year.

It is not added to the IVR bus, which is the instrument regulator bus. This would cause a modern voltmeter to jump all around and never give a constant reading like you describe. The fuel guage and temperature guage are on the IVR bus on an early Mustang... you can't use this for your voltmeter.

06-22-2003, 12:48 PM	#1
Lightspeed Registered Member Join Date: Mar 2002 Posts: 49	electrical problem my original voltmeter doesnt work in my mustang so i decided to put a new one in, i had been having problems with electrical stuff ever since i had the car, well when i put the meter in the needle just starting jumping...it wouldnt ever stay in a steady spot...did i hook it up wrong or what kind of problem could cause this? __________________ 67 coupe, 289 ,c4, bored .40, flat tops, crane powermax cam,edelbrock torker 2 intake, edelbrock perf. 600 cfm carb, accel cleaner, ignitor 2 ignition, hooker comp headers, hooker aerochamber mufflers, H-pipe, b&m 2500 stall, b&m ratchet shifter...and more soon to come....

06-22-2003, 04:21 PM	#2
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Where did you hook it up to? Were you opening and closing the door, or turning on the radio, etc? __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

06-22-2003, 07:30 PM	#3
Lightspeed Registered Member Join Date: Mar 2002 Posts: 49	well first i hooked it up where my radio used to be and it read 12 volts without the key on...then it read 14 when i turned on the car...then i hooked it up to the wires that ran my gas gauge, oil pressure and temperature gauge and on all of those it wouldnt hold a steady pulse...where would the propper spot be to hook it up? __________________ 67 coupe, 289 ,c4, bored .40, flat tops, crane powermax cam,edelbrock torker 2 intake, edelbrock perf. 600 cfm carb, accel cleaner, ignitor 2 ignition, hooker comp headers, hooker aerochamber mufflers, H-pipe, b&m 2500 stall, b&m ratchet shifter...and more soon to come....

06-22-2003, 07:33 PM	#4
Lightspeed Registered Member Join Date: Mar 2002 Posts: 49	sorry i meant it read 12 volts with the key off __________________ 67 coupe, 289 ,c4, bored .40, flat tops, crane powermax cam,edelbrock torker 2 intake, edelbrock perf. 600 cfm carb, accel cleaner, ignitor 2 ignition, hooker comp headers, hooker aerochamber mufflers, H-pipe, b&m 2500 stall, b&m ratchet shifter...and more soon to come....

06-24-2003, 08:08 AM	#5
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	You want to attach it to a hot lead from the battery, and a good ground. Don't attach any other wires directly to that circuit, because if wired in series, it will include their direct load in it's measurement, whereas what you are trying to read is the total overall load. Take care, ~Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

06-24-2003, 07:10 PM	#6
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	on post / ignition switch? Doesn't he need to hook up to the "on" post or "accessory" post of the ignition switch? That way the volt meter won't read at all untill the ignition switch is activated either in the acc. position or the on position. Rev __________________ '66 Coupe, 306, 350-375 HP, C-4, 13.07 e.t., 104.8 mph, 1/4 mi. O.B.C. #2 '66 coupe

06-24-2003, 09:50 PM	#7
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	If he wants to. I run mine off the battery. I don't want to have to rely on the ignition switch working to get a reading. Besides, wiring it through the accessory terminal won't give you an accurate reading of the battery, because other demands will be on when the switch is in that position. If you want to read true battery voltage, it needs to come from the battery itself. Take care, ~Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

06-24-2003, 10:23 PM	#8
gofastmercury Registered Member Join Date: May 2001 Location: calgary alberta canada Posts: 366	Can you leave hooked up like this for long periods of time? How many amps(mili?) will this pull? __________________ 93LXcopcarSOLD14.3@96 @ 4500ft 2.02 60ft on street tires. my 67 ranchero NOT A 390 ANY MORE! 460! 3.70's cast manifolds, comp cams 262H, performer, 750DP 100K out of 79 F250 NEW(oct20/02)14.58@95mph 2.3 60 ft corrects to:13.86@100 66 merc comet351w, isky roller 600 lift 268/260@.050, vic jr. 700DP, 5000stall, 4.56's c-4, 3400lbs with driver 12.3@110 @ 4000ft 1.69 60 ft corrects to:11.69@115

06-26-2003, 03:37 AM	#9
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	I guess it depends on how fancy your voltmeter is. If it's just a regular old dial gauge, the amount of energy it takes to hold that needle in place is a lot less than it takes to preserve your radio stations. I've left my truck by itself without being started for a couple months at a time, and it still started fine on it's own. Of course, I've left my headlights on before to, and had to jump myself from my auxilary battery, but that's another story. Take care, ~Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

06-26-2003, 02:18 PM	#10
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	Same? I think the hot lead at my ignition switch reads the same voltage as at the + battery terminal. Of course mine is a simple, old car with few electrical accessories. The truth is that I still use my old stock amp meter, LOL. I only use the hand held multi-meter voltage meter is if I'm trouble shooting a problem. Rev __________________ '66 Coupe, 306, 350-375 HP, C-4, 13.07 e.t., 104.8 mph, 1/4 mi. O.B.C. #2 '66 coupe Last edited by Rev; 06-26-2003 at 06:21 PM..

06-30-2003, 02:11 PM	#11
Jeff65 Registered Member Join Date: Jul 2002 Location: Oklahoma City Posts: 208	A voltmeter is added to the accessory bus. On '65-'67 Mustangs this is a screw in the center of the ignition switch. On '68 and later, I'd have to refer to schematic wiring for the model year. It is not added to the IVR bus, which is the instrument regulator bus. This would cause a modern voltmeter to jump all around and never give a constant reading like you describe. The fuel guage and temperature guage are on the IVR bus on an early Mustang... you can't use this for your voltmeter.

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