electrical tech questions
Thread Starter
Drifting
Joined: Nov 2005
Posts: 1,795
Likes: 1
electrical tech questions
#1 installed the new radio last night, while i was doing that
the "while I'm at it kicked in"
replaced all the bulbs in the gauge pod with new ones, finished up
really late putting it all back together so i didn't get to check the
lights.
my low fuel light is on constantly now that there is a new bulb in there
and i have over half a tank of gas.
any idea where would i start looking or what would cause this?
by the way its nice with all the gauge lights working now.
#2 staying on bulbs,speedo is lit up nicely but the tach has nothing.
i verified that all the bulbs are good and that the sockets have continuity so that's not the problem.
am i looking at a bad circuit board?
as always any and all answers are appreciated.
yes, even yours nacho
the "while I'm at it kicked in"
replaced all the bulbs in the gauge pod with new ones, finished up
really late putting it all back together so i didn't get to check the
lights.
my low fuel light is on constantly now that there is a new bulb in there
and i have over half a tank of gas.
any idea where would i start looking or what would cause this?
by the way its nice with all the gauge lights working now.
#2 staying on bulbs,speedo is lit up nicely but the tach has nothing.
i verified that all the bulbs are good and that the sockets have continuity so that's not the problem.
am i looking at a bad circuit board?
as always any and all answers are appreciated.
yes, even yours nacho
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
LOL, ok, #1, find and disconnect the float switch at the tank, light will go out or jump the connector and it will go out.
#2, did the tach lights work before? If so, pull it out again and check it out, bad connection somewhere
#2, did the tach lights work before? If so, pull it out again and check it out, bad connection somewhere
Thread Starter
Drifting
Joined: Nov 2005
Posts: 1,795
Likes: 1
Originally Posted by SIXFOOTER
LOL, ok, #1, find and disconnect the float switch at the tank, light will go out or jump the connector and it will go out.
#2, did the tach lights work before? If so, pull it out again and check it out, bad connection somewhere
#2, did the tach lights work before? If so, pull it out again and check it out, bad connection somewhere
no they didnt work before and thats why i figured it was the bulbs.
but i tested them all with my digital meter and all the bulbs and sockets
are good to go.
thats why im thinking the circuit board may be bad.
Thread Starter
Drifting
Joined: Nov 2005
Posts: 1,795
Likes: 1
Originally Posted by Bullshark
Just guessing here, but did you put the wrong light socket in the wrong spot when you put in new bulbs? I am not familiar with the 78
Bullshark
Bullshark
i almost positive i put them all back in the socket where they came out
although there was a mixture of blue and gray sockets.
would this make a difference if a blue and gray got mixed up?
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
Those low fuel lights get flaky after a while...mine never shuts off. About a year ago, someone posted the schematics for a circuit that allows you to adjust the point at which it comes on.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
best I can remember the gray and blue are different, ran into that on my 77 but that was a long time ago. be sure all the instrument lights are the same kind and the warning/indicator lights are the same...I think...
Thread Starter
Drifting
Joined: Nov 2005
Posts: 1,795
Likes: 1
one thing i didnt mention was that the tach has not worked since i bought the car. i figured it was the circuit board on the tach itself.
so,does the circuit board for the bulbs also power the tachometer?
also i can get to my speedo cable and unhook it without a problem
so how hard is it to remove the speedo tach bezel after i unhook the cable?
so,does the circuit board for the bulbs also power the tachometer?
also i can get to my speedo cable and unhook it without a problem
so how hard is it to remove the speedo tach bezel after i unhook the cable?
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Instructor
Joined: Dec 2005
Posts: 116
Likes: 0
From: Snellville Georgia
bulbs
The grey bulbs go in the four corners....same on the speedometer. You have a blue wire that goes in at the top...or maybe bottom...with the blue/pink opposite ( I do not have my pages in front of me). When you pull the tach the color of the wire that goes in a particular hole is stamped on the housing. They should all use the 1835(?) bulb.
I just finished re-wiring the entire dash....if you have an assembly manual, one of the pages in p.235 area clearly indicates the color coding for each hole.
rt
I just finished re-wiring the entire dash....if you have an assembly manual, one of the pages in p.235 area clearly indicates the color coding for each hole.
rt
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
On your tach lights there is a black wire that grounds the tach housing its at the bottom where you can reach it.If you put a regular socket in the low fuel it will be lit all the time.There should be a circuit board on that socket.
Last edited by ...Roger...; Jun 13, 2006 at 04:39 PM.
Thread Starter
Drifting
Joined: Nov 2005
Posts: 1,795
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Originally Posted by dwncchs
On your tach lights there is a black wire that grounds the tach housing its at the bottom where you can reach it.If you put a regular socket in the low fuel it will be lit all the time.There should be a circuit board on that socket.
i may have inadvertantly switched a blue socket with a gray socket
for the low fuel light so i will have to pull that again and double check it.
i will also have to check for that ground wire below the tach.
no tach and no lights on that side of the dash thats why i was thinking the main circuit board may have let go.
Thread Starter
Drifting
Joined: Nov 2005
Posts: 1,795
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took out speedo tach assembly
and found
looks like the outer circuit board is shot.
besides the gauge lights would this board also cause the tach not to work?
also they look clean because i did clean them up a little to see if it would
get the lights to come on
looks like the outer circuit board is shot.
besides the gauge lights would this board also cause the tach not to work?
also they look clean because i did clean them up a little to see if it would
get the lights to come on
Thread Starter
Drifting
Joined: Nov 2005
Posts: 1,795
Likes: 1
Originally Posted by dwncchs
There is just a little clear film peeling off.Did you try the grond wire?
could not find any other wires attached to this unit other than the main plug.
where is it supposed to be?
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
Ok I think I see it in your center pic lower right hand corner.No maybe not--Ijust cant see good enough.Let me check my diagram.Yeh thats it
Last edited by ...Roger...; Jun 13, 2006 at 10:10 PM.
Thread Starter
Drifting
Joined: Nov 2005
Posts: 1,795
Likes: 1
Originally Posted by dwncchs
Ok I think I see it in your center pic lower right hand corner
i need to decide now if i just want to buy a circuit board or try to
get a whole assembly off of ebay or in our C3 for sale section as im not sure if thats whats wrong with the tach also.
is there any way to test the tach?
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
Just a printed circuit will work but if your tach is bad it might be wise to get whole thing.I would try to fix that long enogh to see if that will fix the tach.can you trace that part of the circuit around to the tach leads?I'm trying to trace on diagram to see if that is a ground that is common to the tach.
Last edited by ...Roger...; Jun 13, 2006 at 10:24 PM.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
OK that break is probably responsible for tach lights being out.If you have gauges that work and a brake warning light that works then you have power to the tach.the tach ground is shared with the lights around speedo so that should be good.Check your feed from distributor.Try to bridge that little tear in the circuit.The low fuel warning light socket will not look like the others.