A reversed pair occurs when the polarity of one wire pair is reversed at one end of the link (also called a tip/ring reversal). A crossed (or transposed) pair occurs when the two conductors in a wire pair are connected to the position for a different pair at the remote connector. Split pairs occur when pin to pin continuity is maintained but physical pairs are separated. Refer to the figure below for an illustration of correct pairing, a reversed pair, crossed pairs, and split pairs.

Results Interpretation
In most cases you will expect to see straight through connections. With simple tools, such as LED display testers, a lamp will light up indicating a short or open. Advanced tests, such as reversed or split pairs, are often not available in such equipment. While these tools are usually adequate, it must be noted that a passing result does not necessarily guarantee a correct wiring installation. For example, split pair detection requires the measurement of NEXT or Impedance, which is beyond the capability of low-end testers. Split pairs will cause a high degree of NEXT (typically over 22 dB) which will severely limit available bandwidth on the installed cabling.

In the case of Screened Twisted Pair cabling you will need to verify screen continuity. This is usually only available on more advanced certification tools.

Wire map is a fundamental test, but it is important to note that correct wiring does not verify bandwidth performance. Frequency-dependent tests such as NEXT, attenuation, and return loss are key to ensuring cabling is capable of supporting high-speed applications.

Troubleshooting Recommendations
In the case of a wire map failure, a careful examination of the installation (IDC block or connector) will usually show that one or more wires have been transposed. Inspect and re-terminate as necessary.

If conductors are missing, it could be because they are unnecessary for the intended application. For example, 10BASE-T and token ring each require only four conductors. Some wiring designs purposely use one four pair cable to supply two RJ45 connections each with two pairs. The important issue is to ensure the installed cabling meets the required design criteria.

If an open conductor is found, use the length measurement capability of your cable meter to determine whether the open is at the near or far end to speed fault isolation and repair.