Dash issues-where should I start?

Gotta love that wiring . . .
Posts: 9
Joined: Sun Jul 03, 2011 6:40 pm
Your car is a: 1983 Pininfarina Spider
Location: USA

Dash issues-where should I start?

Postby mldmat » Sun Sep 17, 2017 7:52 pm

1983 Pininfarina Spider

Fuel gauge increases with RPM
Speedometer inoperative
Brake indicator light works but bulb is melted in socket, some damage to speedo plastic
Oil pressure pegs 110 with key on
Directional signals work but dash indicator won't light
Dimmer switch blown. When bypassed, fuse blows
No dash lights, new bulbs recently installed.

Too many issues for it to be one problem. Not sure how to start.

Everything else works fine. Guessing short to ground and I'm not sure how old the melted socket problem is. I can't seem to find replacement sockets for dash lights to eliminate that unknown.

Any help appreciated.

Posts: 2118
Joined: Fri Jan 27, 2006 11:45 pm
Your car is a: 1981 Spider 2000
Location: Wallingford,CT

Re: Dash issues-where should I start?

Postby spider2081 » Mon Sep 18, 2017 8:07 am

I doubt there is a common cause for your problems.
First thing I would check is your alternators output voltage. It should be between 13.75 and 14.5 volts.
The speedometer not working often occurs after dash removal if the center of the cable does not properly mate in the speedometer.
The dimmer and dash light fuse failing would most likely be caused by a short in the dimmable light circuit after the dimmer. Did you replace the bulbs with the correct part number bulb?? Was anything added to the light circuit?
Signals work but dash indicator does not: either dash indicator bulb defective or wrong signal flasher installed.
Brake indicator melted plastic melted: Alternator output voltage too high or wrong part number bulb installed. This light should only be lit continuously when emergency brake handle not full down or brake fluid low. It lights for about 5 seconds when key is first turned on.

Oil pressure gauge pegs: wire from oil pressure sender shorted to ground would cause this. Disconnect the wire from the sender and see what happens
Fuel gauge: Its common for the fuel gauge sender int he tank to loose its ground through the tank. Some people add a ground wire from under one of the sender mounting studs to a good ground in the trunk. Also check the instrument cluster ground above the ignition switch behind the dash.

Posts: 9
Joined: Sun Jul 03, 2011 6:40 pm
Your car is a: 1983 Pininfarina Spider
Location: USA

Re: Dash issues-where should I start?

Postby mldmat » Tue Sep 19, 2017 9:10 pm

Thank you for the response.

Ordered the correct bulbs-received the wrong ones! Didn't notice. Between that and the flasher relay replacement, I'm halfway there.

Thanks for the help, I would have unplugged and plugged in the wrong bulbs a hundred more times before noticing they were wrong...

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