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Brake light on dash stuck on, and electrical woes


rufurt

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Hi All,

 

The Brake light on the dash is on and won't go out in my 1976 Automatic. I checked the connections that are supposed to trigger it. I disconnected the brown/blue wire to handbrake switch, the brake fluid reservoir, and the brake pressure balance switch. The light stayed on even with all those wires disconnected. Since it is a 1976 the Brake light won't light up for low fuel as there isn't a connection for that. Only 2 wires to fuel tank for the gauge.

 

My first thought is that there is a break in the Brown/Blue wire's insulation and that is grounding itself somewhere. When I tested the Brown/Blue to ground I got continuity. I started looking through wires for a break. Haven't found one yet. 

 

Next I took out the instrument cluster. I disconnected the large circular connector. I plugged my multi-meter into the 5 hole (Brown/Blue wire) and then to ground. No connection. That leads me to think that the Brown/Blue isn't grounding itself through a break. I checked 5 to handbrake wire end (Brown/Blue) and got continuity, just to be sure.

 

I then stuck the probe into the 6 hole, Green/White (this is power from the fuse 12) to ground and got the beep of continuity. What? If that already has ground why would the Brake light even be on, wouldn't it short to ground? I checked a few other holes on the circle connector and a few more seem to be grounded to the body?

 

I turned the ignition switch, the lights work, signals work, even the wee lights that light up the gear selector came on. 

 

I am so confused. 

 

Any ideas?

 

thanks,

1976 2002A

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Here's a 75 wiring diagram:

SchPl75.thumb.JPG.1ca256c14447d4af749854973d8dfc6d.JPG

 

#70 manual choke;

#71 soldering spot;

#72 hand brake lever;

#74 fuel sender.

So maybe the soldering spot found ground somehow. It's located at the inner rocker in front of the driver's seat. Did you recently have to weld your car, wherever?

2nd idea: The connector to the manual choke is not hooked up in a 76. Have a look if it's hanging around and if its insulation is still present. These get brittle with the years and can cause short cuts.

Checking the brown/blue for continuity from cluster to lever doesn't tell if it has irregular ground but it seems to be intact.

Check also if the hood release lever and its cable touch something they must not touch. Did you install stereo speakers in the kick area?

I have no idea why fuse 12 has ground. Normally, nothing in the ignition circuit can work then.

 

h

 

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Ok, so BIG thank you for mentioning that this is a '76, as that makes the circuit quite a bit different from the earlier models (including my '75!)  Secondly, your testing method was definitely on the right track, but I think you missed one place that brown/blue wire goes, which I also think is where your issue probably lies, and that's that loathed seatbelt timer relay.  BOTH that brown/blue AND green/white wires go to it, so if it were 'stuck shut' or something I think it would exhibit exactly your symptoms, including the hole 6 reading low resistance to ground.  I think it's somewhere up under the dash, maybe the best way to find it would be to trace the yellow/brown wire from the 'fasten seat belt' dash pod down to it.  Should have 5 wires: yellow/brown, brown/blue, brown/white, white/green, and a solid brown ground.  See if you can find that bastard and if disconnecting it solves your problem!

 

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The Owner’s handbooks may mention a low fuel light, but I’m not certain any U.S.-spec ‘02’s had one. In 47 years of ‘02 ownership (‘67 through ‘76 U.S. models), I’ve never seen the low-fuel light (a.k.a., brake warning light) illluminate for a low-fuel condition.
 

Regards,

 

Steve

 

1976 2002 Polaris, 2742541 (original owner)

1973 2002tii Inka, 2762757 (not-the-original owner)

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1 hour ago, AustrianVespaGuy said:

Ok, so BIG thank you for mentioning that this is a '76, as that makes the circuit quite a bit different from the earlier models (including my '75!)  Secondly, your testing method was definitely on the right track, but I think you missed one place that brown/blue wire goes, which I also think is where your issue probably lies, and that's that loathed seatbelt timer relay.  BOTH that brown/blue AND green/white wires go to it, so if it were 'stuck shut' or something I think it would exhibit exactly your symptoms, including the hole 6 reading low resistance to ground.  I think it's somewhere up under the dash, maybe the best way to find it would be to trace the yellow/brown wire from the 'fasten seat belt' dash pod down to it.  Should have 5 wires: yellow/brown, brown/blue, brown/white, white/green, and a solid brown ground.  See if you can find that bastard and if disconnecting it solves your problem!

 

That was it (I think) the little seat belt that relay. I disconnected it after I found it above the hood latch. The Brake light went out. 

 

Plugged it back in to see if it would replicate the problem. About 3 seconds after I turned the key the relay clicked and the light went out. My guess is it got stuck on after when I moved it around laying carpet. In my struggle to disconnect I think I unstuck it.

 

I am leaving it disconnected as my car doesn't have any of the other bits that make it work anyway. It was a vestigial relay that didn't do anything. 

 

I rechecked and am still getting about 10 Ohms from Brown/Blue to ground. Everything seems to work though.

 

Thanks a bunch. 

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1976 2002A

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2 hours ago, Conserv said:

The Owner’s handbooks may mention a low fuel light, but I’m not certain any U.S.-spec ‘02’s had one. In 47 years of ‘02 ownership (‘67 through ‘76 U.S. models), I’ve never seen the low-fuel light

Me either--I don't think they were fitted to US cars because they would have used the same warning light at the low brake fluid light, and the Feds said that was a no-no.  Same reason US cars didn't get the choke cable with an incorporated switch warning that the choke was on...It too would have used the brake warning light.  

 

mike

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'69 Nevada sunroof-Wolfgang-bought new
'73 Sahara sunroof-Ludwig-since '78
'91 Brillantrot 318is sunroof-Georg Friederich 
Fiat Topolini (Benito & Luigi), Renault 4CVs (Anatole, Lucky Pierre, Brigette) & Kermit, the Bugeye Sprite

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