1972 Granada Mk1 coupe build - Still going... 14-10-2024

I think the VR may be the issue here, but I'm not sure yet. It says 11.72 on the side and I get 11.89 so that would be pretty close. But that is assuming the VR should give 11.72v. It may also be another kind of designation. It is found on both VR's though.

I'll get out the wiring diagrams that will hopefully answer the question of what the VR should put out.

I do now understand why at first I didn't understand the workings. The coil that heats the metal pulls it apart, not closed. I figured it would be the other way around and seeing a permanent contact made me wonder if that was the problem. But I should have thought of that myself. Without the housing on it became a bit harder to test in situ and see what it would do.




So now I know the following:
The in car VR seems to regulate to 11.89v as that is what I measure on the power feed prong when held to ground. But it still over reads quite a bit (by approximately half a gauge).
The out of car VR seemed to have let the full 13.54v from my power source through. This did lead to over reading (and over heating of the gauge) as is happening in the car itself so that is somewhat encouraging. It's also a component both gauges have in common and as far as I can tell it's the ONLY common ground.

I'm not concerned with originality on this binnacle as it's not standard anyway as I fitted a different speedo that works with the VSS signal. So a solid state VR sounds like a good way forward. And if I can find out what one I need, I may even be able to get this changed over myself. Fitting in the original houding would make mounting it convenient so that is a good suggestion too.

So my mission for tonight: see if I can find out more about the regulator.

And thanks Sam for your continued (physical) support. Although with the car driveable I might just come to you this time!

Do you have a variable voltage power supply and a spare gauge / sender? If so take the regulator out and power the gauge directly from the power supply at 10 volts and see if it behaves as expected. That would at least confirm that you should be powering with 10 volts not 12+.

I did find different part numbers for different models of Granada dashes, also for cortina, taunus and fiesta so it would not surprise me. I did see that at least for the Granada ones it's mostly a shape thing. I suspect the innards to be the same.

Maybe a test would be to just keep adding a volt starting from 4 and just see how the gauge then responds to the min and max values of the float sender.

does the guage actually go to max when its grounded ?

p.s if you are struggling for vintage VR, land rover use a BL parts bin 12v > 10v used on smiths guages, readily available, circa 15 quid # 148876

I'll have a look at the link. Yes I thought the vr was also grounded, but looking at the setup and the cluster again I think I may need to double check and retest. The one in the car must be as the led's that are grounded at the ground post of the VR work.

Sounds like either the regulator or the earth is bad on the one in the car. You may find that when the VR also has the load of the temp sender on it that the readings change again.

I seem to remember that you had the LED warning lights glow slightly when they should be off? does that still happen.

I'm pretty much free all weekend this week, least nothing that can't be moved if you want me to come over and we can take a look together.

Hi Sam,

That would be my conclusion too so far. And it's easy enough to test. I also figured the readings would change with more load.

It's amazing, by the way, how the thing works. As it makes and breaks the contact ongoing, but in such a way that visually you can't even see it happening!


Yes, the oil pressure light never goes off completely. It's always on very very faint. But it's only that one, of the three in a row. I do think I used the original ground connection for the binnacle for any of the additions that needed grounding. But poor ground would suit this issue as well I guess.

I'll try and take out the radio, insert and binnacle again tonight and first confirm ground next add ground and then swap VR to see what it all will or will not help.

If I still am stuck, I can be at your place whenever you want. I don't really see the need for you to keep coming to me, unless you consider that more convenient. My storage unit is just that so working in it is difficult as no light even. Outside chances are it's going to be wet as rain is predicted from friday on all through the weekend. I could possibly see if the "isle" in the Barn is available so we could work covered, but there's no guarantee there ever.

Would be great if it all comes down to a poor ground connection though, lol. Been struggling with it for months on and off...

Well I found the time to do some tests in the car. There's good and there's bad....

I now am so experienced that taking out the dash took mere minutes. I thought it wise to just immediately swap the VR as I knew the spare was working right. I had put it back together prior. Swapping this was simple. I hooked the connector back up to the binnacle and switched on the ignition. Nothing, no movement of the gauge. I was just about to measure when a bit of smoke emerged. I quickly switched off the power, but the damage was already done. What seems to be the ground track on the flexible backboard has burned away over a 30 cm length.




I'm not quite sure why it happened. I didn't touch anything yet with the probes and the binnacle was stable.

As I didn't find anything wrong I adjusted how the VR sat on the connections as that was where the damage started. I tried the cluster again and now the fuel gauge read over immediately. I then added a ground wire between the VR and the body and the gauge dropped to empty, which the tank very well may actually be...



I then started the car as no more smoke and everything seemed to work normal. I now was focussing on the temp gauge that usually goes up quite fast too. But it always does take some time. I may not have been patient enough or something, cause the gauge would now not move at all. Even when I removed the additional ground wire to the VR the gauge stayed dead. I may have to be more patient though but I didn't want to kill myself in my garage... But the thinking is if one gauge now works, the other should too. They both share their feed. The temp may just need more time to register.

I don't understand why the ground of the VR would be bad. All ground wires are attached firmly to clean metal. Also other devices like the speedo take their ground from the same wire and that works fine. Same for the coil relay solution to get my tacho working. By the way, disconnect this and the faint glow in the oil pressure light is gone.

So I think I have found my problem and it's an easy fix, but I don't really understand why it is a problem. So for now I don't think I need Sam after all.

The bad is that I now have the fun job of fully dismantling the binnacle to change out the flexible board...on both clusters! Ah well, nice job for when it is raining this weekend... I do hope no more smoke after this and I will be adding that extra ground wire. Maybe this part was weak already and part of the problem?

Yes that is why I'm a little hesitant. But I looked around and nothing else shows any sign of an issue. I presume it must have been the cluster contacting something it shouldn't have as it was balanced on the steering column. Also I wasn't happy with how the VR sat. So the two combined?

You are always welcome! And yes weather has improved as opposed to what was predicted before. I'm going to try and swap the board tonight so I'll be ready whenever weather permits.