There's two black wires coming out of pin 14, which should be power through the IVR and then to the gauges. But I'm not sure where it comes from on its way to the dash connector?

 

There's no power to the IVR because there's no power to pin 14 on the connector, as far as I can tell. So the issue is somewhere between the battery and the instrument cluster connector, before it gets to the circuit board. I'm not sure where pin 14 comes from, but it's some kind of ignition-switched 12v power cable to power the gauges through the IVR.

 

I believe my key was in "run" but I could be wrong... I assume the fuel tank selector must also be on that particular tank? Or do they both get power at all times? I will test it again to be sure.

My assumption is that none of the sending units will get power if the IVR isn't getting power. I would venture to guess that the power comes in through PIN 14, through the IVR, through the gauges, and back out to the sensors through ground wires, and that the movement of the gauge is based on the impedance of the ground wire? But I'm just making assumptions here. If that's the case, that would explain why none of my sending units show voltage. I just wasn't sure about the fuel tank, since it's got two wires rather than one. Seemed like maybe it always had power?

Also how do you get the "Originally posted by ____ " on your quotes?

 

Here's the Instrument Cluster Connector Pin-Out that I found, I think it's mostly accurate:



I have power to 11&12 at all times, 1, 11, 12 with the key on, and 1, 7, 10, 11, 12 with the headlight switch and key both on. Never have power to 14.

Apparently I'm getting power to the right turn signal when the headlight switch turns on... My blinkers don't always work as they're supposed to, which I don't really care about (mostly an offroad/farm truck). But I figured I'd point it out in case it's relevant to another issue.

 

Press the "Quote" icon at the lower right of a post you want to quote.

I looked at the diagram and it looks like the #30 black/green goes to the ignition switch connector, where it gets joined/shares a terminal with #297 blk/grn, which comes from the fuse box and appears to power various accessories in the dash.

I'm guessing that you can route some accessory power to that wire in terminal position 14, and the gauges will probably work - but definitely continue to do your own research...

 

Correct. The only sender you will see power to is the one selected by the dash switch. Which by the way, are sometimes a failure point with gauge problems.
The earlier switches were more problematic though. The later ones were actually quite reliable. But if the IVR does not get power, then nothing else after it does either. So yes, you're on the right path.

correctomundo

Correct again. First is 12 to 15 volts in (depending on whether the engine is running or not) and a pulsing voltage out that averages out to somewhere between 5 and 7 volts. The factory gauges are heavily dampened so you don't see the pulsing. If you were to connect an aftermarket gauge to a factory IVR like ours, you'd see the needle pulsing all over the place.
Next in line is out of the IVR to the three gauges. The Water Temp and Oil Pressure then go out to their respective sensors. The fuel gauge in your case next hits the selector switch.
After the switch, it then goes to whichever tank is selected. Which means, as you suspected, that only the sending unit selected sees the signal passing to it.
From the sender's input wire, it runs through the variable resistor and then out to ground. So the resistance is in the sender, and any added resistance in any of the wires will increase that, and lower the reading on the gauge.

I think it was mentioned that you can test the wiring to make sure, simply by pulling the 2-wire connector off the sender and jumpering one to the other. If the gauge needle goes to a level above FULL, then the wiring is fine and a sending unit could be bad.
This assumes power is getting there however, which in your case you've already determined that it is not. So back up to the instrument cluster and dash wiring.

I would pull all the fuses out (yes, ALL of them) and brush the contacts clean, then reinsert the fuses. Just in case one of them has built up some hard-to-see corrosion and is not allowing power to pass through.
Just a good maintenance practice with these old rigs. Might not help here, but it won't hurt, and might lead you to a fault somewhere.

As was mentioned, you first start by using the "quote" button before making your reply. This takes you to the "Go Advanced" page automatically and will show a begin-quote and an end-quote for the entire post.
You've probably seen two ways to use this if you want to separate it into multiple sections and answers. Some will simply enter their answers where appropriate and change the font color to make them easier to read. I do that too sometimes, but prefer this method for separating each of the sentences I want to answer separately.
Just highlight the first quote (looks like this: ""). If you don't use both the begin quote and end quote, you won't see them highlighted. You'll just see a string of characters written out instead.

Clear as mud?

Paul

 

If you look at your notfication e-mail, you'll see that I forgot, as I often do, to put the end-quotes (" [/QUOTE] ") at the end of each of the sections I wanted to quote.
Oops!
Went back and corrected it though, so all you'll see here is the proper setup.

Paul

 

Your chart corresponds with what I have found on my test plug. 11 & 12 are for the alt gauge (surprised they show power, how many volts?).

14 appears to be a resistance wire, at least that is what is coming out of the plug I use to test gauge clusters. I am not sure how much this resistance wire steps down the voltage, if I ever have the cluster out of my personal truck I will measure it. I can't recall right now where the power comes from for pin 14. Is there a fuse marked gauges???

 

Without looking, I'm guessing that 11 and 12 are for the ammeter. I tested those terminals when I was troubleshooting my formerly non-working ammeter. With the engine and accessories off, they should both show (the same) battery voltage. But it would be interesting to get two identical volt meters and connect one to each of those terminals, and see if they differ at all during vehicle operation.

 

I think it was around 12v for 11&12. Should be the battery voltage. I'd assume it goes up with the alternator on, or down if you're using power without the alternator running.

There's a fuse marked "INST. PNL" but it has power only with the headlight switch on, so it's just for lights. Other than that, I'm not sure. But I don't think the gauges go through a fuse. Though if I remember right, I have power to both sides of every fuse at the appropriate times anyway. So I have no idea why I'm not getting power to PIN 14 (IVR). I also can't figure out why I wouldn't have dash lights, since I DO have power to PIN 10.

 

 

I went to the junkyard yesterday and I grabbed a matching instrument cluster from a 1985 Ford Van. So now I have a hard plastic backing, as well as a spare set of gauges and printed circuit board, and so forth, for just $20.

I tested the gauges off the newer one with the battery, and I tested the PCB for continuity in various locations. It appears to be working fine. Same part number printed on the new PCB. My original backing was in good shape when I first removed it, but every time I touched it (or looked at it too hard) it broke a little. So I swapped it out for the hard plastic backing last night, and got everything put back together. Also tried the other PCB, and neither change made a difference to my situation (still no gauges or gauge lights). But glad to have the hard plastic backing now.

 

What is that number?
Maybe you have the wrong PCB from the start. I kind of doubt that Ford was still using the same PCB nine years later - they sure changed them a lot in the '79-'86 Mustang/Capris.
Your truck is a '76? I'd be expecting to see a PCB with something like a D4, D5, or D6 engineering number on it. Your truck for sure did not roll out of the factory with an E4 or E5 PCB in its dash. I'll bet money on that...

Even the one or two letters and numbers (suffix) at the end are the same?

 

The gauge lights are on a different circuit than the voltage to/from the ICVR. I'm sure you've checked the bulbs.

 

The old PCB is stamped with D6TF10C956 and the new one is D6TF-10C956 (only difference is the dash). So both my '76 F150 and this '85 Van had a D6 number.

The old one has an ink stamp of 6B62P and the new one is 1178520072 (or so it appears, it's half worn off).