Electrical gremlins..

[Lo100469]

Hello all.

After months of works on papers and maintenance, i finally have the car back and took it for a ride.  What a pleasure to drive, power is enough, handling is light and precise, brakes are good, i joined a picture just for the pleasure of sharing.  The car was running a lot better at the end because it has been sitting for nearly 9 months without running much. 

Now of course i have a small electrical issue (note, my mechanic did install a kill switch under the glove box and a new ignition, the lights for the gauge are not working since then but that could be something else). Problem is that I had no gauge working (fuel and temp).  So i went to the fuse box and had high resistance on both fuses.  I cleaned the box and fuses with a a small wire brush and contact cleaner, retested, all good.  But after 2 min i lost the gauges again (and everything else on the same circuit, brake lights, indicators, ...). I stopped, reseted the fuses, gauges back for 5min then gone.  But after 20 miles, they were back and only moved back to 0 when i was braking, then after another 20 miles everything was working (indicators were ok and i can see the amp meter going negative when i brake) but I was home.  Is this car fixing itself when you drive?

I will recheck the fuse box again on the green wires, maybe i did not clean the bottom bracket enough.  I will clean the ground cable i see near to the fuse box.  Then i will search for the voltage stabiliser, maybe there is a bad connection there too.  Anything else obvious i'm missing? Everything on the other circuit work (lights, high beam) and the horn is working too but that is yet another circuit i believe.

thanks and have a great day!

Lo

 

 

[John Morrison]

Congratulations,

that is a lovely TR, and you have her back just in time to enjoy the Spring and Summer.

You are at the centre of this particular problem, the fuse/fusebox being the only common denominator on these circuits.

Did you change the fuse, or simply re-fit the old one?

Glass fuses can have an break inside the end cap that can cuse symptoms such as you describe.

John.

[RogerH]

Hi Lo,

defo replace the fuses with NEW.

 

Roger

[RobH]

1 hour ago, RogerH said:

defo replace the fuses with NEW.

 

Do make sure you get the rating right though.  As discussed in earlier threads, Lucas fuses are rated differently from modern glass fuses.  

 

[Chrisinstevenage]

Find the voltage stabiliser (footwell right of and above the accelerator pedal). Check the circuit there. Those two instruments are common to the VS. I had this issue (on / off at random) and it was a fractured wire coming from the stabiliser.

[keith1948]

Hello Lo

Check the fuse carrier holds the fuse securely. Had that issue on my car. The other thing is to check your earthing points. Bad earth is a common fault in my experience and can cause all sorts of unusual things to happen. Most 'interesting' one on my car was the high beam warning light coming on when I pressed the horn push. A bad earth on the horn circuit was somehow trying to earth via a different route. The earths on the gauges are connected to the threaded studs that hold the gauges in place. There are knurled nuts holding them in place that can come loose. Also more than one gauge can be linked together by the earth wires so it can affect more than one. The lights not working on the gauges could either be faulty bulb, faulty bulb holder or feed wire or bad earth. Pull the bulb holder out of the gauge, switch on lighting circuit and then use a bit of wire to earth the bulb holder. Bulb should light up. If it does then problem is earth on the gauge. If not then it is the bulb/holder.

Oh and check your fuse rating as mentioned above.

Keith

[Bfg]

Lights for the gauges not working might simply be the rheostat. or the white/red wire that connects to the daisy chain of instrument lights.   If I twiddle with the adjuster on mine, the gauge lights will come on ..but only with the dial in one or two places.  It's on my job list to thoroughly clean it.  Also if you have LED bulbs in all the instruments, the original Rheostat isn't keen.  I now have LED's in each of the minor instruments and filament bulbs in the speedo and rev counter.    For LED bulbs Bob recommends swapping the rheostat with a volume control from a radio.  I haven't tried it (yet) but I will.  Thanks Bob.

Issues I had with the fuel gauge and temp mis-reading was simply down to poor earthing of the voltage stabilizer. The inside of the car had been painted (albeit only in primer) and the stabilizer's earth is through its mounting bracket. The layer of paint was preventing a decent earth.  I removed it (just one screw at the bottom, and the top of the bracket hooks under), power wire-brushed the bracket on the side of the foot-well to remove that paint and any surface rust that had been painted over, smeared it in Vaseline to prevent corrosion, and refitted the stabilizer. All was then well.  

If it is the green wire from the fuse box to the stabilizer, then that of course can be loose (or dirty) at either the fuse box or the stabilizer.   Perhaps your pulling the wires off the fuse box, to clean those contacts, was just enough to pull the loom where it passes through the bulkhead grommet. The voltage stabilizer is just there, on the inside of the bulkhead, and any movement of the main loom, might well tug that green wire connection.  

NB. if it were the fuse itself or the fuse-box..  then other components on that green-wire switched circuit ( ie., the brake lights, the heater fan, the wipers, and the indicators) would also be having issues.

Pete. 

 

^ The voltage stabilizer positioned very awkwardly, in the top corner of the driver's footwell, just by where the wiring loom goes through the bulkhead, is earthed through its bracket. A layer of paint on the body's bracket can prevent that electrical contact ie., its earth.  There is just one screw to remove the stabilizer, as its top is hooked under the body's bracket.   

 

Edited April 17, 2022 by Bfg

[Lo100469]

thanks everyone! that gives me plenty of things to check this weekend.  Fuses i ordered from Rimmers were indeed 35A, so i ordered some 25A as per your advice.

will check fuse box again, put new fuses, check voltage stabiliser and all connections around there to start with.

cheers,

Lo

[Lo100469]

Hi all,

i cleaned the fusebox again and checked the voltage stabiliser, the problem was there.  Bad green cable connection from the fusebox and the screw attaching the stabiliser to the body was loose too, so probably bad ground connection.  100 miles done today, no issue, brake lights, indicators, gauges all working.

Now i can move to the next problem. I lost the speedo (refurbished with new cable and new angle drive) mid way. Annoying if we have to change the angle drive again as it is a long job.

Also had some engine hesitations in the first 5 miles (4 or 5 times small hic hups) but that went away completely so probably old fuel and lack of use as the car has been sitting 8 months without running with the same fuel in the tank and no stabiliser.  I thought maybe the fuel cap safety unit I bought from Marco could cause an air lock, i removed it and refitted later in the day realising that if Marco sells those, the problem is elsewhere.

Thanks ! Happy Easter,

Lo

[Bfg]

Well done for identifying and sorting out the voltage stabiliser wiring.  Must have been satisfying to sort something out and then to go for a good drive. One day I guess I'll get there ! 

Issues I've had with speedo drives on my motorcycles was that the inner was just a tad short, and so the square end didn't quite engage.  Maybe your cables will tighten up just a little, both ends. ? 

Happy Easter

[Lo100469]

Hi Pete, just saw your latest post, not fun to discover water in the oil.  We all follow your progress with great interest, you will get it right and the when you do this car will be great. You will get there!

[james christie]

Wrong thread

Edited April 18, 2022 by james christie
Wrong thread!

[Bfg]

4 hours ago, Lo100469 said:

Hi Pete, just saw your latest post, not fun to discover water in the oil.  We all follow your progress with great interest, you will get it right and the when you do this car will be great. You will get there!

Thanks Lo.,  I'm trying !

 

3 hours ago, james christie said:

Wrong thread

I've found lots of those on my car too