Hello, my fuel and temperature gauge only work occasionally. Sometimes, the fuel works and the temperature doesn't and vice versa, or both will work at the same time. Occasionally, I can drive it around and one or more will randomly start working again. I'm assuming it's a bad connection somewhere because I know the 80's Volvo's had wiring problems, but I just wanted to get some feedback before I started hunting for it. Thank you for your time, and all feedback is appreciated.

 

First thing I'd do is take out the instrument pod and refloat the solder on the circuit board with a low voltage iron. There probably are microscopic cracks in the solder that act up at times causing the intermittent problems, refloating them should take care of it. But also, '87 are really bad for the disintegrating wiring, hopefully this is not your issue...

 

The nuts that hold those gauges to the circuit board come loose - and prevent an electrical connection. The terminals in the round plug get loose, and on the temp gauge the temperature compensation board has poor connections creating erratic temp readings. - many methods to solve that, a new temp compensation board, a bypass board (ipd sells one for $8) or this guy has easy ideas to make the temp gauge more reliable. Take care to not FRY your speedometer by plugging in the extra wire behind the cluster (on some cars) in the wrong place when you put it back together. And check the insulation on the wire to the temp sender under the intake manifold and the multi connector at the Firewall.


240 Temp Faker

 

All good advice for a 240 but the poster has a 740 so the 240 remedies won't work unfortunately as the instrument pods are quite different...

 

My bad - post was in the 240 /740 forum - I should have looked closer at the OPs signature.

 

Thank you I will look into that. Is 87 year models the only one with disintegrating wiring harnesses?

 

Sadly, no. From about 1983 to about 1987.5... but that's not etched in stone. Various conditions may contribute to bad wiring but those years are the worst. You can peel back the wrapping and see, usually under the intake manifold is a good place to check, or anywhere where the coating seems to expose metal strands of wire.

 

Oh I see, just wanting to get to know more about these cars. Again, thank you for the help and also for the information. Have a great day!