Wires to master cylinder and ?

[Gordon Watkins]

I'm struggling to make the wiring connections beneath the dash with my old wiring harness and have question about the wires which go through the front bulkhead to the master cylinder. I see the two wires which connect to the MC but in that same loom there are two brown ground wires. Where do they attach?

I have a dual circuit MC from Klasse 356 which has two spade connectors. Does it matter which wire goes where? I'm sure simple trial and error will show if brake lights work properly.

Thanks!

[Bill Waite]

I am not sure about those ground wires. But, re. the two female spade connectors to the master cylinder brake light switch, they just both need to be connected. It does not matter which goes to which post on the switch. Switch merely makes the connection between the two.

In the YNZ harness they are labelled #29 and #33 as follows:

#29: In-line connector for tail light/engine harness to stop light switch (either terminal). Connects with #29 in fuse box to under dash harness.
#33: Stop light switch (terminal opposite #29) to in-line connector for signal/dimmer switch (Match wire colors in switch with wire colors in harness).

YNZ 29 AND 33 REV. 2.jpg (175.58 KiB) Viewed 1223 times

[Doug McDonnell]

wiper wiring.JPG (60.34 KiB) Viewed 1196 times

I think the 2 grounds got to cigar lighter and base of mounting for windshield wiper.

[Jim Liberty]

No ground wire on the lighter. ……………...Jim.

[Hugo Karasawa]

Here two wire loom diagrams that appeared in the Registry's magazine.
I do not see the two grounds close to the brake switch connectors.
Hope you can identify those cables.

[Gordon Watkins]

Thanks for the responses! I've been making my way through Greg Bryan's wiring series but hadn't gotten to the one with Bill Romano's great drawings of wiring harnesses so thanks for bringing those to my attention, Hugo. I'll definitely print those out. My suggestion is to include those drawings in the tech articles. Even better, a compilation of Greg's articles.

But unfortunately they don't answer my question. My two brown ground wires are in approximately the location of wire #17 for the hand break switch except that they "Y" out of loom AL, not out of AE, as shown in the upper drawing. The grommet shown in Bill's photo of the brake switch spades in my harness (with old grommet still in place) covers the combined AL/AK looms so I'm sure those grounds went somewhere under the fuel tank and not under the dash.

These drawings are for a C car and mine is a T6B. Wasn't the Hand Break Switch for the C only?

Still scratching my head.

[Doug McDonnell]

Yes handbrake switch was C only

[Mike Wilson]

And the C doesn't have a wire for an accessory switch as it didn't have one.

[Greg Bryan]

Gordon - Is your car a '62?
Perhaps those wires have something to do with remnants of the bottom sending unit harness for the fuel tank - it would be one brown and one green. I know a lot of '62s have been converted to top sender units and I assume it would require some rewiring - abandon the old sending unit wires and install new wires to the new upper sending unit.
Just a guess …..

[Kevin Wills]

Gordon - Is your car a '62?
Perhaps those wires have something to do with remnants of the bottom sending unit harness for the fuel tank - it would be one brown and one green. I know a lot of '62s have been converted to top sender units and I assume it would require some rewiring - abandon the old sending unit wires and install new wires to the new upper sending unit.
Just a guess …..

You might be on to something there, Greg. On my 62 with an original harness, only 4 wires come out above the bulkhead on the driver's side. Two for the gas tank sender and two for the master cylinder. No other wires nearby...

[Gordon Watkins]

I'll bet you're right Greg. My car is a '62 with a replaced fuel tank with top sender. But both wires look brown (although one could just be especially grimy) and both have continuity to ground.