How can I use the wiring already in my Turbo Coupe to run the voltmeter in an SN95 cluster??
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.
Sweet, it's easy!! :hick:
ok, and what do I need to do with the ammeter circuit without having the gauge in there? Anything?
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.
Beautiful! Thanks :D
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.
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.
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.
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.
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...
yeah but that was isolated to the TC only iirc.