Troubleshooting

A bench test with the entire system wired up, but testing individual cues, revealed a strange condition; on all five slats the first two cue LEDs were lit when either the orange pair or blue pair were connected (cues 1 or 2). Keeping in mind the following protocol:

Orange / orange-white pair = cue #1

Blue / blue-white pair = cue #2

Green / green-white pair = cue #3

Brown / brown-white pair = cue #4

This pattern was found at the output of the jx box. Testing at the output of the panel is even stranger, with LEDs 2 and 3 lit when the orange or blue pair is sampled individually. Again, green and brown (cues 3 and 4) remain in fine working order.

The panel is opened up, and the entire internal wiring build is compared closely with the schematic plan. Everything seems to match perfectly. The same test as above conducted at the internal wiring level (before the CAT5 receptacle) and it performs without flaw. The CAT5 box is problematic!

The receptacle is tested for continuity in two places: the strip where the RJ45 is punched, and the tines that make contact with the cable crimp connector. This test yields an interesting result, that the punched strip, labeled 1 through 8, does not correspond with the tines. More like:

Strip positions: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8

which are cues: 1 - 1 - 2 - 2 - 3 - 3 - 4 - 4

coloured: O - Ow - Bl - Blw - G - Gw - Br - Brw

get moved to: 4 - 4 - 2 - 1 - 1 - 2 - 3 - 3

within the receptacle.

Assumed problem is sketched out, red ink indicates likely issue.

This seems to explain why orange and blue are affected. At some point, probably within the receptacle punching or cables that were crimped up, the blue/white and orange/white are crossed over between positions three and six. Thinking that each cue pair is simply doubled up for a halving of resistance, I need not pay fine attention to the pairing position! For example, orange and orange/white may have originated in positions 1 and 2 respectively, but terminated in positions 2 and 1 respectively, which would create a closed circuit for two cues due to the receptacle mixing up the pairing.

This theory is also supported by the condition found directly in the output of the ignition panel. By using the same receptacles on both transmit and receive sides, they should cancel each other out if the cables and punch strips are pinned out paying attention to the pattern with each pair.

The problem is with the cable as the testing seemed to indicate.  Pins 3 (blue) and 4 (blue/white) are reversed on one end. The end is snipped off, and re-crimped correctly.

One of these cables is not like the other...

The time consumption of this troubleshooting is costly, but I'm no data cable whiz, so as annoying as it is, it's still a learning experience.