08 Sigma 150 brake lights sanity check please

[sigmasmith]

Just about to head out on a reward blat  (reward to myself for too many jobs around the house and garden today).

Did my now customary check of the brake lights before setting off, owing to many trips out being delayed a little by a trip into the pedal box to sort that annoying little brake light switch out).

This time, no brake lights but switch OK.

I'm just about to get a test meter out to check through it all methodically, but my question is connected to whether the brake lights should work even with the ignition off?

I've now convinced myself that the brake lights used to work without the ignition on, but now they do not.

Does anyone know from memory if they should or shouldn't work without the ignition?

 

 

 

 

 

[Jonathan Kay]

Mine need the ignition on, 1998 K.

This time, no brake lights but switch OK.

OK by what criteria? 

Jonathan

[sigmasmith]

Many thanks Jonathan.

There is continuity through the brake light switch, but I think the reason I thought something might be wrong is that the switch got very hot in just a few seconds.  Also both wires to it are showing continuity to ground with the ignition off and battery disconnected at the negative terminal.

Still felt sure that they used to work with the ignition off.  Maybe it was the tintop.

[Jonathan Kay]

... the switch got very hot in just a few seconds.  

There are quite a lot of recorded failures. And a recommended alternative.

Jonathan

[SM25T]

Definitely ignition on. Fuse shared with reverse light.

[sigmasmith]

Hi Ian 

 

Not sure for the sigma.  Fuse chart shows separate fuse for brake lights and reverse light.

 

Any sigma owners, just so that I can put the car away knowing for sure it's ignition on?

Thanks all for your assistance 

[Jonathan Kay]

Have you got a wiring diagram? Let me know if you'd like one.

Jonathan

[sigmasmith]

That would be great if you have sigma one Jonathan.   Have the one from the back of the build manual, but it's more so a schematic than wiring diagram.

[Jonathan Kay]

I've only got that and the layout of the fuses and relays in the Handbook. I really don't like the schematic style. The "standard" wiring colours sometimes help.

Jonathan

[sigmasmith]

Thanks jonathan.  That looks very useful.  I will attack it with fresh eyes tomorrow. 

 

[Jim 123]

I checked my Sigma this morning.  Brake lights only work with ignition on.

[sigmasmith]

Thanks for checking that Jim 

Great news for the car, but not so good for my sanity 

Good to know as the sigma seems to have been wired a bit differently with a separate fuse (even the build manual schematic doesn't show the brake light switch unlike diagrams for other models).

Spare brake light switch is now fitted  and not melting and ready to go 

Time to look into an alternative switch as suggested.

Thanks all.

 

 

 

 

 

 

[Jonathan Kay]

... the build manual schematic doesn't show the brake light switch unlike diagrams for other models...

The diagram I sent you is the 2016 and AFAIK current version including Sigmas. In the engine harness it has:

Please could you check the one you already had, and if it doesn't show that email me a copy.

... the sigma seems to have been wired a bit differently with a separate fuse...

Discussion of the mystery fuse layout.

Jonathan

[Martin J]

I fitted one of these seven or eight years ago & it works perfectly. 

https://www.carbuildersolutions.com/uk/mechanical-stop-light-switch

Threw the standard Mickey Mouse one in the bin.  Piece of junk. You shouldn't have to be cleaning contacts & watching for springs flying out.  

[sigmasmith]

Hi Jonathan,

I've checked my blatmail/email and not seen any diagrams from you, but many thanks anyway.

I was using a copy of the build manual that I scanned way back nearer the time that I built the car.  The electrical schematic doesn't mention the brake switch.  It never occurred to me that it would be on the engine harness schematic - and quite frankly still doesn't make sense! 

The reason that I mentioned the separate fuse is that 2 of my 3 owners handbooks (it was an early sigma after all, so documents were scarce) show that Fuse A = Brake Lights 7.5A and Fuse B = Reverse Light 5A. 

Thanks all and hopefully out in the car this week 

 

Hi Martin,

I think you're right.  I will get a replacement and add the original to my radiator collection. 

[Jonathan Kay]

Doh!

Private Mail sent.

Jonathan

[SteG]

Checked my Sigma - Brake lights only work with ignition on.

[sigmasmith]

Hi SteG 

Many thanks for checking