Wire Harness Tester

Dont know about real time checking, but think about using 74hc138,

This is relatively inflexible, as it will show an error for all the wires that have not been connected, but can be easily expanded in groups of 8.

I'd use a micro, but I dont know if you know how to do that

martin

I've seen one microcontroller-based system that used sequentially timed pulses on each lead, such that no two leads were transmitting at the same time. This allowed for the usual detection of opens & shorts, but also showed mis-wirings and shorts because the timed pulse(s) code appeared on the wrong input.

I want to say it was a Circuit Cellar project a few years back. IIRC, it was targeted at 8-wire connectors, but the scheme could be extended.

Cheers, Richard

I wouldn't use a priority encoder on the input side of this checker. I'd use something like the 74HC151, so your driver can check each input individually. There are certain shorts that a '147-type would mask, which you can see from the truth table.

If it's a dedicated thing (one per harness), then just going one way should work, but you could do a universal thing by having a bunch of I/O pins that can be indivicually set as outputs and inputs. (this means a micro, of course.) Set one output at a time, and real all of the rest as inputs. Then, set that output back to an input, make the next one an output, and so on. Each cable will have a certain pattern to its I/Os.

Good Luck! Rich