I've got a 1986 740 Turbo and I put in a 1987 Yazaki cluster with the old 1986 speedo in it. All gauges work except voltmeter barely moves, hangs in red. The wiring on the back looks nearly identical! True, the 87' blue circuit board is different, but very close. (for example, coolant gauges are made and wired different...)
From my research, it looks like a voltmeter just needs + (positive) source-- which it has in this case.
I did try the old 1986 voltmeter instead and the results were the same. So I know it's not the gauge. My battery is new last year and the old cluster voltmeter was working fine.
Any ideas for me out there??
Thanks, DaN
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