Odd Electrical Gremlin in my 1980 280 SL

[1984 280SL]

a few years ago my 280 SL 110 motor 4 speed manual. started with a Gauge Problem in that when the left turn signal was on -- the Temp and Fuel Gauge would go wonky - the needles would move up and down with the on and off of the turn signal. only the left did this - the right no issues. And yes all the outside turn signals work properly. Additionally when the High Beams were on those two gauges went to peak readings. Standard Headlight no issues. Also when driving the car normally during the day with no headlights on or turn signals on the Temp Gauge would read 20 Deg higher than normal and the fuel gauge would not go below 1/2 mark. Now 3 days ago - all the sudden with no changes to anything in the car.. except very cold 10 deg F, the Gauges , Turn signals, High beams all work like it should - Fuel gauge is back to normal and so is Temp gauge. How can a car fix itself after 3 years of malfunctioning. The problem was not so bad enough to take it to a mechanic and have him trouble shoot, so I just left it alone since nothing other than an irritant was happening.. One mechanic did notice it and just shook his head.
Any ideas from you smart people?

[Sugar Bear]

I've encountered this on another make, the temperature variation is enough to make or break a low current/amperage electrical connection. it is most likely a hairline crack in a printed circuit board or a dirty connection. To fix it I'd remove the instrument cluster, it just pulls out and then clean and tighten electrical connections paying particular attention to ground connections.

It is common for the fuel gauges to act wonky upon their own but your situation sounds more like a dirty or loose connection causing high resistance or an open circuit.

[1984 280SL]

Originally Posted by Sugar Bear

I've encountered this on another make, the temperature variation is enough to make or break a low current/amperage electrical connection. it is most likely a hairline crack in a printed circuit board or a dirty connection. To fix it I'd remove the instrument cluster, it just pulls out and then clean and tighten electrical connections paying particular attention to ground connections.

It is common for the fuel gauges to act wonky upon their own but your situation sounds more like a dirty or loose connection causing high resistance or an open circuit.

Thanks for the reply -- I think at this point since everything is back to perfect -- and the temperature is back to normal around here. as in 45 deg F.. I wont try to fix it.. yes I have had the cluster out many times to see if I can fix it last year to no avail.. I think I will see how the next few months go.,..
I was asking the forum guys here if they ever saw this before and what they think think the problem could be if it comes back like an Ex- Wife.