Gauges Dead - and Generator Warning Light Polarity Reversed?

[pgicante]

All,

I recently replaced the instrument light bulbs for the fuel and water temp gauges on my 1970GTJr - used GE 12V 4W bulbs. Everything seemed OK, but, when driving the car this past Sat. all the electrical gauges went dead (oil pressure, water temp, fuel) and the Generator Warning Light stayed on/went brighter as I revved the engine.... Exterior and Interior Lights still work properly....

Any suggestions?

Thanks,
Phil Gigante
London, ON
1970 GTJr

[JoeCab]

Quote:

Originally Posted by pgicante I recently replaced the instrument light bulbs for the fuel and water temp gauges on my 1970GTJr - used GE 12V 4W bulbs.

[hinchey]

I have that same problem on my 85 Graduate. It started after some fool ripped out my radio. I still have not figured it out so if anyone has any ideas, feel free to pontificate.

hinchey

[Andrew]

Check the instrument circuit fuse, which might be corroded or blown. This has happened to me on a Giulia Super.

Andrew Watry

[pgicante]

The dead bulbs that came out of the instruments were 3W and looked original.. However if 1.2 or 2W is truly original then that's quite the jump.. I'll take a look at the fuse box on the weekend.. Thanks....

[rogerspeed]

Quote:

Originally Posted by pgicante All, I recently replaced the instrument light bulbs for the fuel and water temp gauges on my 1970GTJr - used GE 12V 4W bulbs. Everything seemed OK, but, when driving the car this past Sat. all the electrical gauges went dead (oil pressure, water temp, fuel) and the Generator Warning Light stayed on/went brighter as I revved the engine.... Exterior and Interior Lights still work properly.... Any suggestions? Thanks, Phil Gigante London, ON 1970 GTJr

[Gausie]

Are you losing power at high revs? I had something similar that turned out to be a loose power connection to the starter motor, causing the power to short against the block.

[MitchW]

Quote:

Originally Posted by pgicante All, I recently replaced the instrument light bulbs for the fuel and water temp gauges on my 1970GTJr - used GE 12V 4W bulbs. Everything seemed OK, but, when driving the car this past Sat. all the electrical gauges went dead (oil pressure, water temp, fuel) and the Generator Warning Light stayed on/went brighter as I revved the engine.... Exterior and Interior Lights still work properly.... Any suggestions? Thanks, Phil Gigante London, ON 1970 GTJr

[akitaman]

Just an FYI, but the warning light is so good, that it will illuminate on very low parasitic drain of power. Which means if you are starting develop wire insulation degradation (a short) it can came on. The light on my wife's spider came on and it was because the reverse lights were starting to short at the switch in the tranny. I own a mega-ohm meter so it was easy to find.
Anyway Joecab is 100% correct about over wattage bulbs can and will fuse the wires together. Check and make sure you have no wires under the dash that are blistered or melted together.

[hinchey]

thanks! I think you are right. My mechanic told me he could not get the reverse lights to work and now I read this...I will def take a look. I actually have massive elec. problems so anyone who wants to share a diagram will be blessed and have a candle lit for them. None of my gauges work, the alt. light is on constantly, the heater fan doesn't work nor does the light come on...the car is actually set with a/c but I am too scared to use it...so any help would be appreciated. Again..thanks..

[papajam]

Although doubling the wattage of two instrument light bulbs from 2W to 4W would double the current draw of these lights (from 0.34A to 0.67A), the total draw would still be less than 4A on the entire circuit, well within the 8A fuse rating (assuming that your wiring is as per the diagram). Additionally, the instrument lights (and some other stuff) are protected by fuse #5 while the gauges and warning lights are on fuse #6. Theoretically, one circuit has nothing to do with the other.
As has been suggested, I'd check for a blown #6 fuse.