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98 Eldorado Loaded
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5 Posts
Discussion Starter · #1 ·
Hi guys, here is what I got. blinkers working strong and bright, third light working strong and bright,.... no tail brake lights working at all. " I have" checked the brake pedaL switch ( works fine>with third light that is). Ground at rear is fine as evident of "when disconnected blinkers or parking lights don't work) All possible senerios of lighting all around the car work fine.

If brake lights run through the signal blinker (I didn't unplug and replug to a bad connect) but then blinkers work strong.

what you gentlemen think?

Matt
 

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NONE
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2,027 Posts
have you ruled out the possibility of bad/incorrect bulbs back there? One wrong bulb can screw everything up. I had similar problems on my '97 SLS.
 

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1997 Cadillac STS (BOSE w/AUX In, Massage Seats, URPAS, "Z")
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6,405 Posts
Let's recap:
1. Turning signal fine
2. 4-way flasher fine
3. Parking lights fine
4. 3-rd brake light fine
5. No break lights
Sounds like the switch in the steering column to me.

 

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98 Eldorado Loaded
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5 Posts
Discussion Starter · #4 ·
thanks... yes I have good bulbs because all other lighting senarios work fine..

and.... ahhh the diagram I was hoping for! THX
 

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98 Eldorado Loaded
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5 Posts
Discussion Starter · #5 ·
OH.. and which switch are we talking about? do you have a link I can get that diagram from ..it is a little blurry to me..thks...
 

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98 Eldorado Loaded
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5 Posts
Discussion Starter · #6 ·
ok I think you are speaking of the signal switch assm. ? Is the "third light" switched differently than the tail brake lights then?
 

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1997 Cadillac STS (BOSE w/AUX In, Massage Seats, URPAS, "Z")
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6,405 Posts
As per schematics, the turning signal switch also handles the brake signal.
Notice on the diagram when the turning signal stalk (wand) is in the central position (no signal) that is the NORMAL position. While in normal position the turning signal (GREEN) goes nowhere, so do the 4 way flasher (YELLOW). If brake is applied in this situation the brake signal (RED) goes to E and F (seen as BLUE), where E are rear left turn/brake light bulbs and F (BLUE) are rear right turn/brake light bulbs. The 3-rd brake light (not shown in the diagram) goes straight to the LED strip from S200 (look carefully below the stop switch on the RED line). So the turn/hazard switch has NOTHING to do with the 3-rd brake light.
Now on the upper switch row of the turn/hazard switch observe the arrows. If you turn on the hazard switch then the turning signal (GREEN) is disconnected, so do the brake signal (RED), while the hazard signal (YELLOW) is directed to E and F (follow the thin yellow/red lines inside the turn/hazard switch). So in this situation the turning signal (regardless the direction) and the brake signal are disconnected and the hazard signal is all that gets to the light bulbs.
If hazard is OFF, brake is OFF then observe the turning (GREEN) signal the top switch is close (normal position) and the turning signal is directed to D&E or F&G (depending on the position of the stalk - left or right - observe the arrows).

Hope that helps.
Sorry for the quality of the picture, is scanned from FSM. I am sure I posted a better image but that's what I found first. You can use my CF ID (N*Caddy) and some key words like "turn signal", "brake light" in Google Images, should show up in the first few pages. You can use the CF search as well.
 

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98 Eldorado Loaded
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5 Posts
Discussion Starter · #8 ·
thanks... got it... I would guess dealer only item right... I can get Wholesale pricing so I guess I will get that price tomorrow. couple of hundred I suspect

thanks so much..!!
 

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1997 Cadillac STS (BOSE w/AUX In, Massage Seats, URPAS, "Z")
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6,405 Posts
First diagnose the circuit with a multimeter, no point purchasing parts unless you are REALLY sure you need them.
 

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2007 Cadillac SRX V8 AWD
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1 Posts
I have the same issue... only with mine, the brake and blinker work, but I got nothing when I just have the headlamps on... I work at a Chevy dealer...after parts and labor it's like 5 bills... any ideas?
 

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1995 deville concourse, 97 Seville SLS
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10 Posts
Same problem here, except I have no CHMSL. I do have one bad bulb, which I checked by swapping known good for it. Then, when I was readying to go to the parts house for a bulb, left it out, and THAT"S when I noticed no brake lamps at all....
 

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1997 Cadillac STS (BOSE w/AUX In, Massage Seats, URPAS, "Z")
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6,405 Posts
You don't have the same problem; yours is most likely the brake pedal switch.
Any codes like "no brake pedal detected during deceleration"?
 

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92 sts
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1 Posts
Had the same problem no brake lights, turn and hazards worked, turn signal switch solved the problem.....
AutoZone, orielys, pepboys carry switch under $55
Be sure to get steering wheel puller and lock plate remover.....
 
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