19 replies to this topic

[NLinPEN]

I suspect there's some resistance upstream of the brake switch and it's creating a voltage divider when you operate the brakes.

 

 

Looking at a wiring diagram there's nothing on the same feed, via the top fuse in the fuse box (white to green). Tracing it back through the ignition switch (first suspect) there's a circuit via a line fuse that feeds the instruments: Ignition & oil lights plus voltage regulator. There might be an earth short, but you'd expect the lights & gauges to show something too. Another branch off that line fuse operates the fuel pump relay, the emissions purge valve (switched to ground at ECU) and connects to pin  11 on the ECU, presumably just as an ignition on signal - that would be my 2nd suspect, including everything back to the line fuse. You could bridge the fuel pump relay terminals to eliminate that - then swap in another relay to test for relay or wiring if required.

 

...and,

 

The reverse lights do share the brake light supply & have the same load, so they ought to cause the same fault.

Ethel, thank you for your reply. Are you referring to the attached schematic diagram? This is the only diagram I have that shows brake lights, so I hope it is the correct one. I did notice the connection from the white wire to the green wire via fuse C6 (this fuse is okay, I have inspected it). There is however a notation in the schematic that I don't fully understand. The green wire has a connection point with a black arrow where it says "see power distribution (A)". The white wire has the same. Does this mean that power is coming into joints SJ5 and SJ7 from the power distribution schematic? Or does the direction of the arrow indicate the direction of the current? I'm not sure how to read this.

You might be correct that the reverse lamps would cause the same issue (engine stalling) as the brake lights if it is a bad connection upstream. Unless the green wire has a bad connection at SJ7 going into the switch, then the problem is limited to the brake lights only. To be honest: I have not tested what happens if I put the car in reverse, thus far I have solely focused on the brake lights. Now that that has a workaround with the LEDs I might be able to put the car in reverse. Side question: where would SJ7 be located in the car? I don't have drawings that show where junctions and connectors are located.

If the current is flowing from the brown wire, via the white wire, to the green wire that supplies the brake pedal switch I would need to search for those wires. And probably check the ignition key in the steering column?

Attached Files

•  schematic.png   194.71K   1 downloads

[viz139]

Your theory of a bad connection upstream of the brake switch makes sense and can easily be checked by switching on the reverse lights or heated rear windscreen. for this connection to effect the ignition also it would have to be before the fuse box. If operating the the wipers also cut out the engine the fault would be from the starter motor to ignition switch (brown wire) . If only the rear windscreen heater or reverse lights it would be between the ignition switch and fusebox ( white wire). Could be ignition switch itself. I wouldn't consider the fault even temporarily fixed.

[Ethel]

I was looking in the 69-01 Haynes. Your diagram looks to show the MPI blade fuse box, but it's essentially the same - without seeing what "power distribution A" is about.

 

 

 

Since you mention checking fuse C6, can we assume it's a Japanese export model? I don't know if I have a wiring diagram, but it's likely close enough to the MPI for what we're interested in.

[Ethel]

We have this

 

in here

 

...and also from the depths of TMF...

 

(1996) 24 Fuse Engine Bay Fuse box: -

1 -- 15a -- Rear screen heater
2 -- 15a -- Reversing lamps, stop lamps, headlamp dim-dip, indicator relay
3 -- 15a -- Auxiliary cooling fan
4 -- 15a -- Headlamp dim-dip
5 -- 15a -- Heater blower, sunroof where fitted
6 -- 15a -- Wash / wipe
7 -- 20a -- Headlamp flasher, horn, alarm
8 -- 10a -- Tacho, ECU, fuel pump relay, alarm
9 -- 10a -- Stereo, cooling fan relay, auto gear selector lamp
10 -- 10a -- Stereo memory, interior lamp, indicators, hazards, alarm, brake fluid warning
11 -- 10a -- Fuel pump
12 -- 10a -- Starter relay
13 -- 10a -- Side and tail lamps left hand, number plate lamp
14 -- 10a -- Side and tail lamps right hand, instrument lamps
15 -- 10a -- Main beam headlamp left hand
16 -- 10a -- Main beam headlamp right hand & warning lamp
17 -- 10a -- Dip beam headlamp left hand
18 -- 10a -- Dip beam headlamp right hand
19 -- 20a --}
20 -- 15a --}These fuses reserved for overseas spec systems
21 -- 10a --}and accessories (A/C system, front fog lamps etc.)
22 -- 20a --}
23 -- N/C
24 -- 10a -- Rear fog lamp

[NLinPEN]

I was looking in the 69-01 Haynes. Your diagram looks to show the MPI blade fuse box, but it's essentially the same - without seeing what "power distribution A" is about.

 

 

 

Since you mention checking fuse C6, can we assume it's a Japanese export model? I don't know if I have a wiring diagram, but it's likely close enough to the MPI for what we're interested in.

You are correct. The car is an SPi car, but it does have an MPi-style blade fuse box in the passenger compartment. I believe that it was indeed a Japanese export car, which somehow made its way to Malaysia. I'm the owner of this car since about one year and don't know much about its history. Finding the appropriate manuals takes some time and effort as there have been so many variations of the Mini over the years. Your follow-up post, with the reference to the wiring diagrams is therefore very helpful. Thank you for that.