How to measure resistance of a cable harness connector

[james_p_martin]

Hello All,

I have a cable harness for an automotive to be tested for continuity and resistance, it has a connector at one end(having multiple pins-12 nos.) and open-end at the other which connects to a control unit. The connector pins are supposed to have 50ohm resistance connected to the pins. I have to verify that whether the operator has soldered/connected the 50 ohm resistances with the connector pins. How can I do it?

I was thinking to power the connector pins with 12 V DC and putting a shunt resistance(s) in series with the individual connector pins supposedly having the 50ohm resistance, and then I am planning to measure the 'mv' drop across the shunt to know the circuit current to find out the resistance value connected with connector pins. Can I do it this way?

Please suggest/advice.

Thanks

James

[santo_13]

You could do it multiple ways based on what instruments you've access to,

1. Use a DMM and a Switch Matrix or Multiplexer - use DMM in resistance mode, switch between multiple pairs in your connector and measure the 50 ohm
2. Use a power supply or SMU - source a known small current and measure the voltage required to force that current, calculate the resistance
3. Your method - power up with 12V DC with a shunt in series, measure across the shunt, be mindful of the power rating of resistor and cabling, if there is a short, you might burn the whole harness based on your 12V DC source current capabaility

In general, to measure resistance, you need some kind of current source and voltmeter (this is what happens within a DMM too). A voltage source and ammeter will also work as long as you can limit the current going through the DUT.