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Neither the oil pressure gauge nor temp gauge are working on the truck I just purchased.
Just double-checking - is the purpose of this connector to supply 12v to oil pressure sender, temp sender and coil? Coil is getting power as truck runs so just figuring out if this connector is to blame.
If so can I cut it out, reconnect the sender wires and give each one 12v?
Your guessing. Why do you "think" your connector is bad?
Temp gauge all the way to the right, oil pressure all the way to the left, alt gauge in the middle and none of them change. Thought the connector might be the cause but could it also be the ICVR?
Temp gauge all the way to the right, oil pressure all the way to the left, alt gauge in the middle and none of them change. Thought the connector might be the cause but could it also be the ICVR?
ICVR applies to fuel, temp and oil pressure (if applicable) gauges, has nothing to do with the amp gauge (that usually hardly moves).
f it does turn out to be the connector (which it does not seem to be at this point by the way) then there is nothing wrong with your suggestion to just cut it out and make your own.
I once even used a simple Radio Shack terminal strip mounted to the firewall and put ring terminals and hook terminals on the wires. Worked fantastic for many years.
Originally Posted by prs143
Do you know why one terminal is isolated from the other 2?
If you mean why is one a female pin encased in the the plastic of the connector, that is just their way of "keying" the connector so you can't put it on backwards and create all sorts of drama.
But it also can be one way of isolating a circuit from possible short-circuiting if not careful. In this case though, it's likely just to create a keyed connector.
Originally Posted by prs143
Temp gauge all the way to the right, oil pressure all the way to the left, alt gauge in the middle and none of them change.
Does the TEMP gauge needle go back down to the low side when the key is off? Or is it stuck all the way to the right (full?)?
You say none change, but is that with the key too, or just no change under any conditions? This clue may be important, and would indicate against a problem with the connector.
Originally Posted by prs143
Thought the connector might be the cause but could it also be the ICVR?
Also depends on the answer to the question above. But yes, it "could be" an issue as well.
Originally Posted by prs143
Can anyone advise the best way to test the Instrument Cluster Voltage Regulator?
Well yours certainly looks the age! But if you can get a test probe on both input and output sections/circuits, you can see 12v coming in from the chassis wiring, and as mentioned a reduced voltage of approx. 5-6 volts to the gauges themselves.
These are also typically adjustable so if your output is low or high, it can be altered with a crew or pin.
Also, it's hard to test an original with a digital volt-meter due to it's pulsing output delivering an average voltage. You can watch an analog meter's needle swing, but the numbers on a digital readout don't always follow a consistent path.
Good luck. Let us know if the gauges change with the key or not.
Also, when all the other things are working as expected, in general you can count on a zeroed needle meaning that the 6v signal is not making it out to ground through the sending unit. And a pegged full needle means that the sending unit wire is grounded fully, or almost fully.
The sending units are essentially a variable ground (to the engine) with a range of from 73 ohms (empty/low) to 10 ohms (full/high) or thereabouts. I think there is a finer range rating, but most are just rounded off to the 73-10 range.
You can re-connect the main connector and measure for voltage at the sender connectors (little 90 degree push-on thingies) and you will be looking for that same pulsed signal from the IVR. You may already have done that(?) and found nothing at the sending unit ends? If so and there was no voltage signal at the sending wires, then it can still be multiple things.
In no particular order (or not):
Since you just purchased the truck, have you checked for good grounding yet? Naturally the main ground cable is good or you would not be able to crank the starter. But what about a body ground?
There should be at least two on any of our trucks. One from the battery negative to a nearby body part, and another one from the back of the engine block/intake manifold to the body/firewall. This last one is quite important now that our trucks are 40-50 years old.
Getting a good grounding bond between the body near the instruments, then to the engine block, which is well connected to the battery, is a critical step in any old vehicle like this.
Early Broncos ('66-'77) are a perfect example of why this is important. Unlike many other vehicles, Ford never saw fit to add the additional ground from engine to body at the firewall. This was perfectly fine when they were new, and maybe even ten years old. But rust and general corrosion of parts impeded good connections to the rest of the body. I'm sure they figured "good enough" because all the main body parts were welded together as one unit. But spot welds leave gaps for moisture between the panels and after a few years things started going wonky with electricity.
So even if your truck has them, make sure they've got good clean contact points. And if it does not have the extra ones (they get removed all the time!) then add your own.
And make sure the instrument cluster has a good ground connection to the steel dash if it does not have it's own dedicated ground wire.
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