7 replies to this topic

[supersimono]

Hi all,

Sorry to raise another fuel/temperature gauge post. But I’m struggling to figure it out and I’ve got a deadline of getting it back in the road for my wedding in August!

I’ve had a project car for the last few years and I’ve replaced the front loom when the engine was out so I’m hoping that there are no faults with it. Prior to this, the gauges were working.

Both temperature and fuel gauge do not not appear to work so from what I’ve read this is a sign that the stabiliser is faulty. I have a ‘92 Italian job so this is with the integrated voltage stabiliser.

I’ve tried a bypass by fitting an external one from minispares (BMK1539A).I’ve put insulation tape between the contacts on the internal and connected the external one on the back. Even with this fitted, the gauges do not appear to work. I have tried running the car and put 10LIn the tank but the gauges still don’t move.

All fuses seem to be ok, all other instruments are working. Measuring the input voltage to the stabiliser says 0V.

I’m not the most experienced mini electrician so learning this as I go. I’m very much stuck at this point and it’s the only major thing to fix before I can finish getting MOT and tax done in time for my wedding.

Is anyone able to help and/or know of any mobile car electricians with experience of minis in the Berkshire area?

[alpder]

Input to the stabiliser = 0V would certainly stop it working. Since they were working before, it's also fairly unlikely that the old stabiliser is the problem. Probably worth undoing the changes you've made and then testing what voltage is going into the old stabiliser. If still 0V, then you've identified what's causing the problem and just need to trace back the wires to where the stabiliser should be getting its 12V input from.

[Spider]

Try connecting to Earth the wires that go to the senders, just do this briefly (less than 5 seconds), the gauges should shoot up to the top of the scales. That will 'prove' the wiring, stabaliser and gauges.

 

If that's a no show, then given everything else you have done, I'd next suggest checking you have 12V at the multipin plug on the plain green wire with the key on.

If you have that there, then I'd say it's probably the printed circuit board on the back of the gauges.

[supersimono]

Thanks both.

Unfortunately it’s a new loom so it would be a lot of work to refit the old one.

I try at the multi on connector again, I struggled to figure out which one to connect to but as I’m working o. It today I’ll give it another go.

[Chris1275gt]

I don’t know if the multi plug that connects to the instrument cluster is the same as an earlier 1975 1275gt but you can fit that plug in either way as I did and it throws every thing out. Once found (after what seemed like a lifetime) and put in the correct way all good with no issues.

[supersimono]

It is far to hot to be stuck in the garage today..

So a few things I have found:
The voltage stabiliser bypass I added does work. It is intermittently working because the instrument panel connected is 3D printed and a poor fit (this is how I bought it from Minispares). With ignition on I have no warning lights come up but as soon as I press it down/sideways they come on. I’ve measured 12V and 10v across the so confirmed working.

By pressing the connector in and earthing the temperature sensor feed out I can get the gauge working - confirmed working.

I’ve done the same for the fuel gauge however this does not appear to work. I’ve does a voltage reading on the green/black to battery and have 0V. I have continuity from the sender earth terminal to battery negative.

Am I right in my assumption that it’s basically a fault with the feed to sender (green/black) and is there a way to do a bypass to check the gauge works? I assume the green/black is part of the rear loom, would it be easier to replace the whole thing?

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[Spider]

Given what you've found here, I'm inclined to suggest the printed circuit has some cracks in it. These are hard to spot but under good light, can be seen. I have done repairs to these (when desperate !) by soldering across the cracks. If you do this, leave the PC in place so it takes up it's natural shape. It might give you a temporary fix so at least you can see where you are going with it.

[alpder]

It may well be broken traces. But first thing I'd do with any device like this, where there are lots of mechanical connections, is have each of the connectors out, a spray of contact-cleaner* and plug/unplug a few times while still wet with it to scrape the contacts clean. I'd also have all the screws out - both the ones with and without crimp-eyes on them - and give them the same treatment. Adding star-washers between each contact-point can help to make a better contact, too.

 

With everything unplugged and removed, it looks like it would be simple enough to check continuity of most of those traces. A helping hand to flex the board while testing might identify breaks.

 

*Not "WD40" - it will work at first but then slowly dries to a sticky insulating layer. Although, confusingly, the company also make a pretty decent contact-cleaner which they've also branded "WD40".

Edited by alpder, Yesterday, 08:41 AM.