I'm baffled guys and could use some help... Weird tail light issue: While I was hooking up electricals in the cabin, I noticed the brake light switch on the brake pedal in the cabin was broken. I ordered a new one and went to look for the wires (green + green/purple as per the Book of Lies) to hook it up, but I can't find them anywhere (WTF?). According to the diagram, the lead INTO the brake pedal switch is a switched green lead that goes into the cabin straight from the fuse block, and the electrical current OUT OF the switch is carried to the tail lights by a green/purple wire. Right now NEITHER wire is connected since I can't find either one. Here's the thing... when I switch on the ignition MY BRAKE LIGHTS ILLUMINATE. According to the diagram, this is impossible, since the only way for current to flow into the green/purple stop light wires is via the brake switch. I checked the tail lights by switching the ignition off but then turning ON the main headlight switch and as expected the tail lights (not the brake lights) illuminated. Switching on the ignition immediately illuminated the stop lights, like there's a direct connection between the hot, switched green lead and the green/purple (which I can't see how happened). I tried tracing the wires from the tail/brake lights but they go up into the LH rear a-pillar (behind the gas tank) and I cannot follow them. It appears as if the green/purple wire reappears on the LH side via the front a-pillar hole and then passes through the firewall right near the wiper motor. Beyond that all the wires are wrapped in tape and can't be seen. Ideas? I can snip the green/purple wire up front near the a-pillar and then splice in a new lead to the brake light switch (along with a second, green lead to the switched hot), but I hate the thought of having some weird, random (possibly still hot and short-able) connection somewhere inside the harness... Thanks! --Matt
I'm confused. Instead of using a diagram, why not just use the wires to and from the broken switch to connect the new switch, exactly how the broken switch was attached? I have also never heard of the Book of Lies you mention, or a rear a-pillar, but that is irrelevant. Seriously, I'm not sure why a diagram is needed to replace an existing switch with one just like it. Perhaps you are over-thinking this repair. Did you make a note of which wires went where before removing the broken switch? I would focus on hooking the new switch up the same way the old one hooked up, regardless of what a diagram says. CD
When you get a back feed thru the lights like this it's usually a bad ground connection, I'd check those first. Did you replace the fuse panel as part of the rebuild? New fuse panels have a connective strip between two fuses that the originals did not have - if you did, all you need to do is cut that little connecting strip out. If you didn't then I'm back to the ground wire. Did you hook the switch up exactly like the old one, as CD said? Use your test light, find the hot lead at the brake switch and make sure you have power there, then go to the back and find the correct lead at the brake lights - see if it goes hot when the switch closes (press on the brake pedal)If you have power at the switch, and power at the brake lights when the switch closes, you have a bad ground.
Derp de dur... I got it. Here's what happened: Apparantly when I broke the old switch I snapped clean off the top half (with all the electrical connections) and left the plastic half with the plunger behind on the pedal. Then, when I lifted the cabin heater box, I trapped the (still connected) top half of the switch on top of the heater box - that's why the circuit was complete. I was thrown off by the presence of a green/orange wire with the correct terminal plug - I figured that was one of the wires and the diagram was incorrect (as I've heard can happen) in the Hayne's book aka "The Blue Book of Lies". It wasn't. I don;t know WHAT that wire goes to yet, but it's not part of the brake light circuit. I dug around on top of the cabin heater box, located and retrieved the broken plug, found the green and green/purple wires and connected them to my new switch and all is well! I've still got some things to do, but they're pretty pedestrian at this point, mainly re-connect some accessories like my stereo, driving lights, windshield wiper motor, etc. then renew the interior and the dash area. Oh, and dial down my hi-lows - they're WAAAY too tall. Crashton: no "magic smoke" issues yet, but I DID just install a fire extinguisher in the cabin today, just in case... :cornut: Thanks guys!!
Still lots of DC stuff to re-connect, but I actually LIKE working on electrical for some insane reason... it's meditative and extremely logical and you know right away if things work or not (or catch fire).
Green w/ Yellow tracer is the wire for your heater fan motor, could it have been yellow rather than orange? Glad you got the brake lights sorted.....another box ticked on the list!
Heater fan was (before the engine swap) driven by a temp sensor on the radiator, which triggered a relay on the firewall. The new radiator does NOT have a sensor port, so those wires are disconnected and I was planning on installing a cabin switch to toggle the fan on/off as-needed. Don't know why that wire would be in the cabin, given that the stock setup controlled the fan via the radiator temp sensor...
Oh... well that device is working correctly - by that I mean the fan turns on when the On/Off switch is toggled, anyway. Could it actually be for something else? I've been told that my car (1992, originally I believe) has a slightly wonky, non-standard wiring setup so the diagram can't always be 100% trusted. ALSO, can someone please do me a favor (different issue)? There was a grounding strap attached to the windscreen wiper motor on the LH side of the engine bay, which I removed when I took the motor out for cleaning/painting. Now I can't remember where that strap connected. There's a metal prong that's the usual size for a wiring clip on the housing as well, if someone can tell me what's connected there. ATM the grounding strap is disconnected and I can't find any disconnected wires near the wiper motor that have the correct-sized electrical plug, but they may be trapped underneath unnoticed (??) Thanks!
A lot of cars had a ground strap that went to the hood hinge for radio noise suppression, maybe post a pic of the strap for us? I don't know if I would agree with your characterization of the Haynes manual as a book of lies, rather there were so many running changes thru out the Mini's life, I don't know if any one book can catalog them all. For example, Haynes had a brake bleed procedure that wasn't in my Bentley manual, but it was the right one for Buzz. I don't know if I would have ever gotten the rear brakes bled on Buzz had I not found that in the Haynes book. Likewise the electrical schematic for Buzz doesn't show a rear fog light, but the wiring harness had the correct colour wires - as they were found in a later model year schematic and Buzz has one, and it looks factory installed.
BTW Matt, that light green/orange wire is the power lead for a factory tachometer - not that you couldn't use it for something else.....I've seen this in a lot of imports, they build one wiring harness, and whatever options aren't on the car, they just leave the extra wires dangling. The solid green wire powers the heater fan motor, and the light green/yellow wire goes to the windscreen washer pump motor. Hope that helps.
Re-hooked the wiper motor leads and the wipers work - the grounding strap (still disconnected) seems to do nothing. I re-connected the stereo (aftermarket) as well, and there's no electrical whine or feedback with the strap off. Not sure WHAT it went on at this point...
I think I've figured out why some of the new Lucas fuse boxes have a couple of the terminals joined (hidden from view on the backside of the box). Apparently there are two versions of the fuse box that look identical: One version is used by Minis without the hidden connector, and the other one used for some MGs that needed the terminals to be joined. Seems a lot of the suppliers of British parts stock just the MG one (which, as Minidave points out, needs to be modified for use in a Mini). As an illustration of the MG box with the extra connector you don't want for a Mini, see here: FUSE BOX , 4-FUSE, MGB FROM C187211, C187841 1970-1980. Lucas brand for MG MGB (1968 - 1980). #37552