radio and dash lights don't work
Thread Starter
Junior Member
Joined: Sep 2010
Posts: 17
Likes: 0
From: Maine
Car: 1989 Formula 350
Engine: 5.7l
Transmission: auto
Axle/Gears: BW 9 bolt w/3.27 gears
radio and dash lights don't work
I have a 1989 firebird formula I just bought that has a strange problem. When i turn the headlights on the instument cluster goes dark and the radio loses power. Everything else works as it should and as soon as I shut the lights off the radio gets power back. Any ideas as to what could cause this?
Supreme Member
Joined: Jan 2006
Posts: 3,341
Likes: 12
From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Light Fright
Using a voltmeter or test light (the type for testing for voltage, not a continuity tester) probe the INST LPS fuse, while the switch is in the HEADLIGHTS ON position, and you are rotating the dimmer control back & forth.
Is there is power there?▬Steady or it varies?
Then do the same test with the switch in the ALL LIGHTS OFF position, and you are rotating the dimmer control back & forth.
Is there is power there?▬Steady or it varies?
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Happy Racing!
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I Didn’t Wreck, The Track Moved
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Is there is power there?▬Steady or it varies?
Then do the same test with the switch in the ALL LIGHTS OFF position, and you are rotating the dimmer control back & forth.
Is there is power there?▬Steady or it varies?
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
I Didn’t Wreck, The Track Moved
.
Joined: Jul 2002
Posts: 1,983
Likes: 6
From: Stamford, New York
Car: 80 SE/TTA;88 T/A GTA;86 T/A
Engine: 4.9L Turbo; LT1; empty
Transmission: TH350; T56; empty
Axle/Gears: 3:23 disk; 4:10 disk ; 3.42 disk
Re: Light Fright
Does this have an aftermarket radio? A hack job would be where to start if an aftermarket radio was installed. Just one more area to look into.
Supreme Member
Joined: Jan 2006
Posts: 3,341
Likes: 12
From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Light Fright
OK due to the fact there’s no power at the INST LPS fuse, but the instrument lamps illuminate when the headlight switch is OFF, makes it sound like there has been rewiring by the PO.
Let’s find out if the responsible part of the headlight switch is good.
Using your test light or meter, probe the dark green wire at the headlight switch, when the headlight switch is in the HEADLIGHT ON position, and you are rotating the dimmer control back & forth.
If there is power there, you have a broken connection from that point, to the INST LPS fuse.
If there is NOT power there, the headlight switch is defective and might have been bypassed by the PO.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
I Hit The Water Barrels Because My Car Was Dirty
.
Let’s find out if the responsible part of the headlight switch is good.
Using your test light or meter, probe the dark green wire at the headlight switch, when the headlight switch is in the HEADLIGHT ON position, and you are rotating the dimmer control back & forth.
If there is power there, you have a broken connection from that point, to the INST LPS fuse.
If there is NOT power there, the headlight switch is defective and might have been bypassed by the PO.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
I Hit The Water Barrels Because My Car Was Dirty
.
Supreme Member
Joined: Apr 2010
Posts: 4,337
Likes: 29
From: Aurora, OR
Car: 87 IROC Z28
Engine: 355 cid TPI
Transmission: Custom Built 700R4 w/3,500 stall
Axle/Gears: QP fab 9" 3.70 Truetrac
Re: Light Fright
Another possibility is a failing fuse link at the starter. There are three fuse links at the starter. One protects the alternator charge circuit, one provides power to the ignition switch, the other provides power to the light switch. If these fuse links are damaged or if there is a poor connection at the starter, it could cause excessive volt drop when the head lamps are turned on.
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