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No Brake lights...  Rating:  Rating
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 Posted: 07-04-2005 03:30 pm
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JASPER
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Joined: 03-13-2005
Location: Valencia, California USA
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Still trouble shooting the rear brakes -

I have a dead circuit and can't find the cause - any help would be appreciated -

I have working front/rear indicators, reversing lights.

No lisence plate lights, brake lights or side lights.

The switch at the brake peddle is good.

Now what ? oh and I noticed that the wiring at the light switch DELTA replacement) and the switch itself gets VERY hot when the lights are on - is this normal or a fire waiting to happen !

cheers al

James + JASPER #18149

Attachment: Jasper.jpg (Downloaded 81 times)

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 Posted: 07-04-2005 08:46 pm
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Mark Rosenbaum
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The brake circuit is pretty simple.  You'll need a voltmeter to check things out.  The one in the dash won't do but almost anything else is acceptable.  I'll presume that both brake/tail light bulbs are known to be good, by actual test, and that the car has a good, charged battery.

1.  Starting with Fuse #2, you'll see three Green wires on one end of it.  Verify the presence of +12V on each of the wires -- do not merely check voltage on the metal part of the fuse clip, but puncture the insulation with a needle or sewing pin and stick your test lead to the needle or pin.  If one or more of these wires does not have voltage, the fuse block has gone bad, or the wire was once shorted to the chassis somewhere in the harness, and has burned up its connection to the fuse.

2.  Locate the brake switch on the pedal cluster.  There should be a Green wire on one of its pins.  Verify the presence of +12V on this pin.  If not, the car is mis-wired or the Green wire is broken inside the loom.

3.  The second pin of the brake switch should have a Green-Purple wire.  NOTE: this switch is normally open, and closes when the brake pedal is pressed.  With the brake pedal NOT pressed, there should be no voltage on the switch pin.  Press the brake pedal and verify the presence of +12V on the pin.  If no voltage, the switch may be defective,  or is not being mechanically activated, or there's a high-resistance path between Fuse #2 and the switch instead of a low-resistance wire -- e.g. a burned up connection as noted in step 1. 

4.  The Green-Purple wire runs to the rear of the car and directly to the socket of the LH brake/tail light, and coming out of the socket a second Green-Purple wire runs to the RH brake/tail light.  Have an assistant press the brake pedal and verify the presence of +12V on both of these wires -- again, use a needle or pin to check the actual wires.  If no voltage, the car is mis-wired or the Green-Purple wire is broken inside the loom.

5.  Now, with the brake switch still pressed, slip the voltmeter probe through the hole in the LH brake light socket's rubber boot and make contact with the metal shell of the socket.  If more than about 0.1 volt is seen, the ground is bad.  If this occurs, the socket spring prongs may be corroded, the conductive plating in the lamp assembly may be bad, the blade connector that connects to this plating may be bad, or the Black wire in the loom that connects to chassis may be bad.

6.  Repeat steps 4 and 5 for the RH brake light.

All of the remaining lights are on the same circuit, and the Beam switch in the turn signal assembly selects between Low and High beams.  Neither the Lights switch in the dash, nor its wiring, should ever feel hot, though on a cold day you might perceive a very slight warmth with the high beams on.  Odds are, you have a short or near-short in the wiring, one or more defective light bulbs, are using very-high-current light bulbs, or something of that nature.  The license plate light sockets tend to short out against the trunk lid if you use the wrong 'festoon' bulb -- the next smaller US size is just a bit too small and one must squeeze the little copper clips together a little so that it will fit.  The passenger door courtesy light has the same problem.  The correct British bulb isn't generally available in the US except from places such as Delta.

Finally, if nothing at all makes sense, disconnect all the lights in the entire car, and remove all the bulbs, then restore and test each connection/bulb, one item at a time, until problems start to occur.

 

Last edited on 07-04-2005 08:47 pm by Mark Rosenbaum

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 Posted: 07-04-2005 11:41 pm
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JASPER
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Thanx Mark

Looks like I've got my work cut out for me !!

I'll let you know how I get on -

cheers

James

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 Posted: 07-06-2005 12:00 am
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John Kimbrough
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Jasper, have you looked at my electical troubleshooting spread sheet on my web page.  It may give you some help.  http://home.comcast.net/~jrkengr2/

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 Posted: 07-06-2005 01:32 am
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JASPER
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Thanx John

I forgot about your excellent wiring diagrams -

I'm sure they will help a lot

cheers

James

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