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Topic: Ammeter to Voltmeter...? (Read 2028 times) previous topic - next topic

Ammeter to Voltmeter...?

How can I use the wiring already in my Turbo Coupe to run the voltmeter in an SN95 cluster??
1988 Thunderbird Turbo Coupe
'89 5.0 w/ ported intakes, Mallory Adjustable FPR, BBK shorties and H with 2.5" Flows, 130 amp 3G, 89 Mustang comp/wiring, Aluminum radiator w/ elec fan, T5 trans, King Cobra clutch, 3.55 gears, 13" Cobra brakes (front), Wilwood prop valve, Mustang A-arms, Front Coil-overs, MM CC plates, Silver 17x9 R's, 03 Cobra IRS, Aluminum DS, 2002 Mustang dash/console etc..., custom leather seats

Ammeter to Voltmeter...?

Reply #1 –
Simply connect the voltmeter to any ignition-switched 12V power source. If I were doing it I'd tap into the ignition feed for the cluster itself.
2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

1988 5.0 Thunderbird :birdsmily: SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

Ammeter to Voltmeter...?

Reply #2 –
Sweet, it's easy!!  :hick:

ok, and what do I need to do with the ammeter circuit without having the gauge in there? Anything?
1988 Thunderbird Turbo Coupe
'89 5.0 w/ ported intakes, Mallory Adjustable FPR, BBK shorties and H with 2.5" Flows, 130 amp 3G, 89 Mustang comp/wiring, Aluminum radiator w/ elec fan, T5 trans, King Cobra clutch, 3.55 gears, 13" Cobra brakes (front), Wilwood prop valve, Mustang A-arms, Front Coil-overs, MM CC plates, Silver 17x9 R's, 03 Cobra IRS, Aluminum DS, 2002 Mustang dash/console etc..., custom leather seats

Ammeter to Voltmeter...?

Reply #3 –
Connect a 470-ohm 1/4 watt resistor between the two ammeter circuit wires. This will simulate an ammeter in the system and will allow the alternator to charge.
2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

1988 5.0 Thunderbird :birdsmily: SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

Ammeter to Voltmeter...?

Reply #4 –
Beautiful!  Thanks  :D
1988 Thunderbird Turbo Coupe
'89 5.0 w/ ported intakes, Mallory Adjustable FPR, BBK shorties and H with 2.5" Flows, 130 amp 3G, 89 Mustang comp/wiring, Aluminum radiator w/ elec fan, T5 trans, King Cobra clutch, 3.55 gears, 13" Cobra brakes (front), Wilwood prop valve, Mustang A-arms, Front Coil-overs, MM CC plates, Silver 17x9 R's, 03 Cobra IRS, Aluminum DS, 2002 Mustang dash/console etc..., custom leather seats

Ammeter to Voltmeter...?

Reply #5 –
Quote from: Thunder Chicken;206132
Connect a 470-ohm 1/4 watt resistor between the two ammeter circuit wires. This will simulate an ammeter in the system and will allow the alternator to charge.


Not a bad idea, but probably unnecessary... The TC/Sport use a shunt type charging system... Yet to see one that will not charge without the cluster installed...

If you're going to install the resistor though, use at least 1 watt... While a quarter is fine, physically it's rather fragile and easily damaged...

Ammeter to Voltmeter...?

Reply #6 –
Quote from: TurboCoupe50;206172
Not a bad idea, but probably unnecessary... The TC/Sport use a shunt type charging system... Yet to see one that will not charge without the cluster installed...

If you're going to install the resistor though, use at least 1 watt... While a quarter is fine, physically it's rather fragile and easily damaged...

Actually you're right - I was thinking of base cluster cars with a TC instrument cluster swap (like mine). There is no shunt with base cluster cars - the "I" terminal on the alternator gets its feed through the "BAT" light and will not charge with a cluster swap unless you put a resistor in that circuit in place of the bulb. The base cluster has a built in "shunt" to allow the alternator to charge if the bulb burns out, but if you take the cluster out entirely it won't charge.
2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

1988 5.0 Thunderbird :birdsmily: SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

Ammeter to Voltmeter...?

Reply #7 –
470 ohm?

Isnt that basedon a max voltage drop of about 5mvdc?.  Ive always been curious that if a 3g were done that the resistor value would need recalibrated.

Of course all this is a ratio anyway but still.  I suppose you could use your clamp on and compare the cluster reading to the actual reading.


My stock 20th and stock 351 bronco draws 44 amps with everything on exluding the movement of door locks, seats, and other various transitional current draws.

Ammeter to Voltmeter...?

Reply #8 –
I base my 470 ohm figure on what I measured across the two terminals (10 and 11, plug "A") on a base cluster. I think it was actually around 500 ohms but a 470 ohm resistor is easier to come by.
2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

1988 5.0 Thunderbird :birdsmily: SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

Ammeter to Voltmeter...?

Reply #9 –
As I recall from those 3G alternator threads awhile back , the ammeter shunt wire was in the wiring harness near the alternator not in the instrument cluster.

In my car I installed a Radio Shack volt meter and hooked it to the cigarette lighter. It is hot all the time so I can see the differance in voltage before and after starting.

But if your cluster is like the one in my 01 GM you can't tell what the voltage is, just whether it's "normal" or not.

Ammeter to Voltmeter...?

Reply #10 –
Quote from: softtouch;206227
But if your cluster is like the one in my 01 GM you can't tell what the voltage is, just whether it's "normal" or not.

Yeah the mfgrs have dummied down the gagues in many cases till they are no more useful than idiot lights(maybe less so)...

Ford has been using a switch and resistor to operate the oil pressure gage since about '90... No matter what the temp, engine speed etc, always read approx 2/3-3/4 scale... My '93 Lightning has this setup...

A friend had the front cover recall on his 4.2 F-150 done by Ford and they managed to dump coolant in the oil... It started knocking the next day, but the gage still read 3/4... luckily they admitted their goof and installed a new engine...

Ammeter to Voltmeter...?

Reply #11 –
Quote from: softtouch;206227
As I recall from those 3G alternator threads awhile back , the ammeter shunt wire was in the wiring harness near the alternator not in the instrument cluster.

.


yeah but that was isolated to the TC only iirc.