3rd brake light

[Deleted member 138290]

Couldn’t get another test light locally so used multi meter. Tested pin 22 and got good earth aaa meter beeped. Then depressed pedal with ignition on and along with good earth got 11.96v s...... so what’s going on with my electrics ?

 

[Deleted member 138290]

And every time I try to upload photo s they are always to big ! Even after I shrink them !

 

[pmcgsmurf]

Couldn’t get another test light locally so used multi meter. Tested pin 22 and got good earth aaa meter beeped. Then depressed pedal with ignition on and along with good earth got 11.96v s...... so what’s going on with my electrics ?

You get 12volt at pin 22 on the rear SAM when pressing the brake pedal?

Trace pin 22 to the appropriate coloured wire, GreeN/YEllow (GN/YE ?), I'd find this close to the SAM and use a sharp probe to pierce the wire and check continuity then check this right up to the light unit.
If continuity is broke then you need to start stripping the harness down to find the break (what I'd do) or run a new cable (what I wouldn't do).

 

[pmcgsmurf]

And every time I try to upload photo s they are always to big ! Even after I shrink them !

Shrink them further then.

 

[Deleted member 138290]

Yes almost 12volts when pedal has been pressed. Lol pin 22 plug which has 2 thin wires no 2 and 3 and then there s a thicker wire on same plug ( I’m colour blind so I have to be very careful what I touch etc) which doesn’t seem to do anything when connected and there was no power to it when I stuck the red prong in it ? It’s all mind blowing to me lol and considering the actual 2 wires that go directly to the 3rd brake. One is to the earth along with all the other wires for the rear lights and the other (stripped) goes from another plug further down on the SAM..... I think my only option is to get booked in at the diagnostic bloke in Newark as he will understand it all and probly know exactly what to do..... £36 inc vat for an hour ain’t bad.....

 

[Deleted member 138290]

No idea how to make photo s smaller !

 

[Deleted member 138290]

 

[Deleted member 138290]

Well bugger me...... I need another trip to spec savers !

 

[Deleted member 138290]

Well, as of this morning my electrics just got worse ! Started car and put blower on and noticed steam coming from driver mirror ..... dropped window and put my fingers on the glass to find it warm..... well to say I hadn’t even put rear heated window/ mirrors on ! AND only the driver mirror was warm...... ffs this car will end up going up in smoke at this rate !

 

[Deleted member 138290]

So back to my brake light issue..... just tested the 3 wires that come out of pin 22...... when pedal depressed and tester connected the meter shows 0.03-8 volts ????? So I’m assuming power cut off to that bit of wiring ??? And I guess ideally I would need to trace those 3 wires all the way to the front of the car ??

 

[Deleted member 138290]

I’ve got that wrong I’m sure ! As pin 4 on the SAM shows 11.96 volts......

 

[Deleted member 138290]

So done some more diagnosing just now and my audio system is now draining the cars battery in approx 20 sec s !!! I did a voltage test and after disconnecting the unit from the dash the convenience warning didn’t come up for a good 15 mins I would say..... also the OCP module is now not communicating and when I tried the sunroof button it was as if the battery had been disconnected but the sunroof wouldn’t reset to the button so ordered another module. Still got to replace the wiring harness for drive side mirror as up/ down still not working but waiting on loom to be delivered..... also still trying to work out where the short/ open circuit could be causing the led brake light fault but I’m defo thinking a split in a wire somewhere....... between the rear SAM - the brake light switch..... going to see if my auto elecy mate has a better scanner that might pick up more fault codes than what mine will and see if he can find out exactly.....