electrical system => wiring harnesses => Topic started by: mkoloc on March 14, 2020, 04:24:40 PM

Title: Brake Light Wiring / Light Switch
Post by: mkoloc on March 14, 2020, 04:24:40 PM
Just about finished with my wiring project.. everything on my dash works like it should to include volt meter,  instrument lights, rheostat, etc..   I did not realise that I have a 4 position light switch when I was setting my wire harness up and I would like to use it. My understanding of its purpose is to provide the brake light only option in the last position on the switch.  The wire diagram shows the number 14 wire ( from strip on firewall) going to the SW lug on the light switch.  That is one of the wires from the brake light switch..it currently is running to the TT lug on the light switch (3 position light switch).  The diagram shows broken/ slash dotted line running from the TT lug to the SW lug.  It states:  Dotted line connection to SW terminal with 4 position switch when TT terminal is not used. So it seems that I just need to move that wire from TT to SW terminal.  Just checking if I'm reading that correctly.  What does the TT do on the light switch?

Major issue: I replaced my VM main harness with a pristine original, but left the VM rear harness in place.  Hooked all my rear wire harness to the firewall strip (4-15) all checked out with the following exception.   I have one wire that does not fit into the schematic... it attaches within the harness to one of the two wires running to the brake light switch.  Wires # 14 and 15 run from the strip to the brake light switch on the rear harnesses.  This excess black wire is on the same circuit as my number 14 wire (circuit test confirms that) but I cant figure out where it goes on the strip. It's just sticking out at the end of the harness.  I can account for all the other wires and the only lights not working on the track right now are the service stop light and BO stop light.  Brake Light Switch:  #14 currently runs via the strip thru main harness to TT on the light switch.  #15 runs "   " to SS on the light switch.  Given that, I should have brake lights with the exception of using the SW position on the light switch.  What I can't figure out is where that additional black wire attaches on the strip??? And why don't I have brake lights.   

I am going to recheck all my wiring from the resistor to the trailer socket tomorrow to make sure that's synced up .. that may be the issue and I already confirmed that the 3 single connectors on the rear harness at back of the track more plugged in.  Even then I still have that extra wire that is tapped into my #14 wire running from the brake light switch.. has anyone else using a VM rear harness run into this issue .. My VM rear harness does not even match the wires diagram they sent with it (ISSUE) and of course they did not include the wire diagram showing the light pedestal system, so it's not reliable.

Any and all suggestions appreciated.
Title: Re: Brake Light Wiring / Light Switch
Post by: mkoloc on March 25, 2020, 09:58:14 AM
Have all issues resolved and that wire did not run to the brakelight wire, turned out my helper was touching the wrong wire when I was under the track doing continuity checks.  The wire in question turned out to be hot whenever the light switch was in the HT configuration.  All my lights work correctly to include blackout, dash, trouble etc so the harness was good to go with the exception of that single wire.

Fast forward to Monday when I recieved a voicemail from Joe Hall, the previous owner of Vintage Wire of Maine! 
Called and had a very pleasant conversation with Joe yesterday.  Joe is restoring a 1942 M2 and reads the forums, saw my post and called to assist.  That really made my day.  I had since figured everything out except for that wire with help of a pedestal light type schematic from Steve and Jon.  After conversing with Joe, we determined that the wire had probably been added to the harness by accident and was there to tie into the dipper switch. Of course I have no dipper switch on my model so its just excess and now tucked back into the harness. 

I so appreciated Joe's call and concern regards my issue.  Outstanding customer service from a gent who no longer owns the business but did when I purchased my harness years ago!