Volvo dash help -

[Txriverrat2001]

Greetings from Texas ! I'm currently updating my Cruisers 3020 Aria which has KAD42's in it. I've recently purchased a pair of Garmins to update the dash and move the analog gauges to digital within the screens. When I removed my dash panel I found what appears to be 2 test light housings wired in-line on the ground circuits of each tachometer. Anyone have a clue why they would do this ?? Pic attached - TIA

 

[BruceK]

Bit of a long shot guess. Given the age of the engines, thus boat, they may be a suppressor of sorts so as not to interfere with DECCA navigation before the widespread use of GPS.

 

[superheat6k]

I wonder if they are the ballast resistor loads to excite the alternators via the VP modules that show the Oil, Water temp, Generator and other alarms.

 

[julians]

Yeah I'd go for them being alternator exciters, but don't know for certain.

 

[Txriverrat2001]

I know the only way to get the tach's to read - is to bump the throttles past 1200 RPM or so - then they start to work.

 

[BruceK]

well they're not there to excite the alternators then. If they are not suppressors to shield DECCA systems then the only other thing I can think of is do they warm up? Particularly when the dash lights are activated. If so, I have similar but in plates behind my dash and switches. It's to prevent water condensation forming around gauges and switches. You know misted gauge prevention.

See one here on top of my dash switch diagram