Hi,
I have a 1990 Volvo 240 GLT which has a rather frustrating issue. On an irregular basis the Tachometer and other instruments ( excepting the Speedometer) either fail to register or stop working during normal use.
By pure trial and error or basic luck I have found that turning on the heater switch the instruments burst into life. On occasions the heater has been operating for a short time before the instruments begin to work.
I considered that this issue may be an earth problem.
Has anyone any idea what could be causing this issue?
Any assistance will be gratefully received.

 

Have you done a wiring check on the wires that go to the dash board?