Possible Bad Dash Dimmer
05-19-2010, 12:07 AM
#1
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Possible Bad Dash Dimmer
Hows it going? My dash lights are out and have replaced the under-dash mounted rheostat. They worked fine for about 4 months and all of a sudden went out again. Could the dash mounted dimmer wheel switch be the culprit this time?? If it is, I'm s.o.l. since they're discontinued.
Thanks,
Phoenix
Thanks,
Phoenix
06-07-2010, 03:14 PM
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Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Use Some Wheel Polish On The Dimmer Wheel
It could be the dimmer wheel but first do some measurements.
Using a voltmeter or test light (the type for testing for voltage, not a continuity tester) probe the dark green wire with the WHITE stripe going to the dimmer wheel.
When you rotate the wheel back and forth — what happens on the meter or test light?
Then probe the brown wire.
When you rotate the wheel back and forth — what happens on the meter or test light?
Then probe the probe the plain dark green wire.
When you rotate the wheel back and forth — what happens on the meter or test light?
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Happy Racing!
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If People Drove Any Slower They’d Be Going Backwards
.
Using a voltmeter or test light (the type for testing for voltage, not a continuity tester) probe the dark green wire with the WHITE stripe going to the dimmer wheel.
When you rotate the wheel back and forth — what happens on the meter or test light?
Then probe the brown wire.
When you rotate the wheel back and forth — what happens on the meter or test light?
Then probe the probe the plain dark green wire.
When you rotate the wheel back and forth — what happens on the meter or test light?
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
If People Drove Any Slower They’d Be Going Backwards.
06-07-2010, 04:18 PM
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Car: 1988 IROC
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Re: Possible Bad Dash Dimmer
06-07-2010, 10:40 PM
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Re: Possible Bad Dash Dimmer
It could be the dimmer wheel but first do some measurements.
Using a voltmeter or test light (the type for testing for voltage, not a continuity tester) probe the dark green wire with the WHITE stripe going to the dimmer wheel.
When you rotate the wheel back and forth what happens on the meter or test light?
Then probe the brown wire.
When you rotate the wheel back and forth what happens on the meter or test light?
Then probe the probe the plain dark green wire.
When you rotate the wheel back and forth what happens on the meter or test light?
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
If People Drove Any Slower Theyd Be Going Backwards.
I appreciate the info guys.
Later,
Phoenix
06-09-2010, 08:47 PM
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Re: Possible Bad Dash Dimmer
Nina,
I used a probe test light to do this small test and my results were:
Dark Green/wht strp - on
Black - off
Brown - on
white - off
This must mean the rehostat I replaced is bad huh? I appeciate the info Nina now I know its not the switch. Quick question, I recently had to replace my + battery cable. It had exposed wires and wasn't held down by anything so it basically hung there and would swing when I made a sharp enough turn and probably touch the pully. Would this cause my rheostat to blow again in such short time? I do recall when they went out a second time, I did a u-turn to head the opposite direction and later that night noticed they were out. Thanks again in advance.
Phoenix
I used a probe test light to do this small test and my results were:
Dark Green/wht strp - on
Black - off
Brown - on
white - off
This must mean the rehostat I replaced is bad huh? I appeciate the info Nina now I know its not the switch. Quick question, I recently had to replace my + battery cable. It had exposed wires and wasn't held down by anything so it basically hung there and would swing when I made a sharp enough turn and probably touch the pully. Would this cause my rheostat to blow again in such short time? I do recall when they went out a second time, I did a u-turn to head the opposite direction and later that night noticed they were out. Thanks again in advance.
Phoenix
Last edited by The_Phoenix; 06-17-2010 at 10:01 AM.
06-14-2010, 08:56 AM
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Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Use Some Wheel Polish On The Dimmer Wheel
In your test you say on or off however if the remote dimmer was working correctly the test light or meter would have not been on or off as you rotated the rheostat back and forth but would have shown a smooth rise or fall of power in step with the rheostat.
Also, probe the INST LPS fuse while you rotate the rheostat back and forth.
What are your finding on the INST LPS fuse?
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Happy Racing!
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I Didnt Jump The Start, The Flagman Was Late
.
Also, probe the INST LPS fuse while you rotate the rheostat back and forth.
What are your finding on the INST LPS fuse?
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Happy Racing!
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I Didnt Jump The Start, The Flagman Was Late
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06-17-2010, 10:14 AM
#8
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Re: Possible Bad Dash Dimmer
Yeah when I would rotate the switch all the way up for the dome light, it would just come on and turn off when rotated on the 'off' position. I forgot to mention in my previous post (sorry) that I purchased a used switch in good condition locally from a guy here in my area from an '88 GTA. I installed it and no guage lights still. Thats how I came to the conclusion that the under-dash mounted transistor is bad but I could be wrong. I'll post later on what I found with my INST LAMPS fuse. Thanks again NINÅ.
Phoenix
Phoenix
06-20-2010, 05:50 AM
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Re: Possible Bad Dash Dimmer
Hey there 
Just wanted to say, its hard to trust the head light switch/dimmer once it is un-installed. I pulled mine out, and it fell apart in my hands. It was crusty and just trashed. Went and bought a new switch from AZ and fixed my problems. Had to do a lil work as a piece of plastic inside was busted but it worked great. The black plastic piece in the next posted picture had stripped threads so I drilled out a brass piece of hardware from Lowe's and used that as that in its place, as seen here:
Just wanted to say, its hard to trust the head light switch/dimmer once it is un-installed. I pulled mine out, and it fell apart in my hands. It was crusty and just trashed. Went and bought a new switch from AZ and fixed my problems. Had to do a lil work as a piece of plastic inside was busted but it worked great. The black plastic piece in the next posted picture had stripped threads so I drilled out a brass piece of hardware from Lowe's and used that as that in its place, as seen here:
Last edited by resinlake; 06-20-2010 at 05:54 AM.
06-20-2010, 11:08 PM
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Re: Possible Bad Dash Dimmer
Not a bad lil mod for those of you with camaros 
. Nina, I probed the 'INST LPS' fuse and rotated the wheel and ignition on. What I got was a constant 1.5-2 volts and nothing else, no gradual more-or-less on the voltage meter. The under-dash transistor is to blame in that case correct? I really appreciate the info.
Thanks alot,
Phoenix
. Nina, I probed the 'INST LPS' fuse and rotated the wheel and ignition on. What I got was a constant 1.5-2 volts and nothing else, no gradual more-or-less on the voltage meter. The under-dash transistor is to blame in that case correct? I really appreciate the info.Thanks alot,
Phoenix
06-21-2010, 12:14 PM
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Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Use Some Wheel Polish On The Dimmer Wheel
OK, disconnect the transistor, then probe the dark green wire with the WHITE stripe going to the dimmer wheel.
If the rheostat is powered and OK, you will now see the rise and fall in voltage when you rotate the wheel back and forth when you have the headlight switch in the parking lamps position.
Now probe the brown wire.
If the wire there is OK you will see the voltage go from zero to 12 volts when you turn off & on the parking lamps.
If all of the above happens replace the transistor with a Motorola OC28 or equivalent.
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Happy Racing!
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After The Fourth Barrel Roll I Lost Control Of The Car
.
If the rheostat is powered and OK, you will now see the rise and fall in voltage when you rotate the wheel back and forth when you have the headlight switch in the parking lamps position.
Now probe the brown wire.
If the wire there is OK you will see the voltage go from zero to 12 volts when you turn off & on the parking lamps.
If all of the above happens replace the transistor with a Motorola OC28 or equivalent.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
After The Fourth Barrel Roll I Lost Control Of The Car
.
06-23-2010, 09:25 PM
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Re: Possible Bad Dash Dimmer
Fixed! I Did the final tests and I did notice the rise and fall of voltage on the meter. Brown wire showed 0-12 voltage changes as well. Bad transistor! I went to the junk yard today and pulled 2 transistors off of an '88 and '86 firebirds. They're both motorola brand transistors, one is a 8B21 and the other which is already installed and working, is a 8B03 if i remember correctly. The unit I replaced was new when I bought it and is a Mallory brand BM0504; I bought it from rock auto. I appreciate the info and testing procedures NINÅ thanks a bunch. My lights now light up at night. Now the reason they burnt out in the first place has to be when I had my positive battery cable hanging by the pulley. If thats not bad enough, it had wire exposed on it so must of tapped the pulley when I did a u-turn to go to my friends house. Thats been fixed btw.
Thanks alot,
Phoenix
Thanks alot,
Phoenix
Last edited by The_Phoenix; 06-24-2010 at 10:36 PM.
07-08-2012, 02:20 PM
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Re: Possible Bad Dash Dimmer
Just wanted to ask how you were able to get that remote dimmer under the dash out. I took the trim panel off and pulled down the convenience center and am able to touch it. I can't even see the darn thing, let alone remove it. I need some tips from someone who's been there and done it.
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