Dash lights fuse keeps blowing

[rex LT]

Dash gauge lights fuse keeps blowing out in my 1984 944.

The dash lights up with a new fuse, once the car is started, blows out within a few seconds.

What troubleshooting would I perform to diagnose this issue?

Thanks in advance

[Jfrahm]

Check the tail lights circuit also.

[rex LT]

Originally Posted by Jfrahm

Check the tail lights circuit also.

could you please explain more

[sausagehacker]

IIRC there are a couple things on that circuit, including the gauges on the center console and maybe the cigarette lighter. Check the wiring diagram to be sure.

[pfarah]

Rex,

Have you always had this problem or is it a recent issue?

[rex LT]

Originally Posted by pfarah

Rex,

Have you always had this problem or is it a recent issue?

I've had the problem for about 4 months. Before then, in my previous two years of ownership the lights were good.

[Jfrahm]

If you have a decent ammeter see how much current the circuit is drawing. A small DMM might not be big enough.

Usually the tail lights circuit is connected to the dash lights so the driver knows if their tail lights are out. Look at your fuse diagram for related fuses and pull anything for the rear lighting, then see if the instrument lights start working, that will narrow things down. A bad bulb socket out back somewhere like the licence plate lights would be suspect to me. Any dodgy rewiring done back there should be looked at.

Ash tray and glove box lights are likely connected, lighter socket likely is not. Aftermarket stereo wiring should also be considered. Miswiring the lighting circuit to the head unit could cause this. Pull the harness to the head unit.

[guru944]

Rex Lt;

Does this happen also without starting vehicle and power + accessories is "on"

Reverse current and Ground loop is defiantly present.

Is vehicle store inside or outdoors?

If outside, rain may have grounded a printed circuit board or relay in fuse box; recommend start there...
keep us posted.
r

[rex LT]

Originally Posted by guru944

Rex Lt;

Does this happen also without starting vehicle and power + accessories is "on"

Reverse current and Ground loop is defiantly present.

Is vehicle store inside or outdoors?

If outside, rain may have grounded a printed circuit board or relay in fuse box; recommend start there...
keep us posted.
r

vehicle is stored outside. The lights work fine before the vehicle is started, once started, within a couple seconds the fuse blows

[Shifter]

I had a similar issue on a 968, and it was the dash light dimmer rheostat. Not certain if the early cars can have the same problem.