Check all connections.
This post is part of a series describing the generic, high-level troubleshooting process. Side effects include, frustration, annoyance, hair pulling, possible bad language, and thinking out-loud.
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What is Troubleshooting?
Simplified Troubleshooting Overview
Step 1. Understand the correct inputs and outputs of the “black box.”
Step 2. Determine which output(s) are incorrect.
Step 3. Figure out which input(s) affect that output(s).
Step 4. Verify that those inputs are as expected.
Step 5. Analyze the path(s) from input(s) to output(s).
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Step 7. What are the devices in those path(s) that change the data?
Step 8. Eliminate the devices that could not cause this output.
Step 9. Test the remaining devices.
Step 10. Repair/Replace faulty device(s).
Step 11. Fully test the system.
Step 6. Check all connections.
”The Jim Sweet patented swiping action.” That’s what we called it in one of my previous lives, where I learned this “trick” of disconnecting and reconnecting connectors. Contacts in connectors will build up corrosion which can completely stop equipment from working. Sometimes it is the obvious, everything is green or white, level of corrosion, sometimes it is so little (maybe a piece of dust) that simply disconnecting and reconnecting a connector will dislodge the problem and fix everything. Sometimes a little contact cleaner will do the trick. Other times you will need to replace contacts or entire connectors to get rid of the bad connection.
I can’t tell you how many times that I have taken something apart looking for a problem, not found one, given up and put it back together, and like magic… it works perfectly. When this happens, it is both satisfying and annoying. I like to know what fixed it just as much as I like it to be fixed. Often what fixed it is like the number of licks to the center of a Tootsie Pop, “The world may never know.”
Whenever possible, disconnect every connector in the path (one at a time) looking for corrosion, broken wires, recessed pins, bad crimps on contacts, anything that is not right. Also take a look at any splices and replace any that are suspect. Fix or replace anything that you find in this step. Whether you find anything or not, its a good idea to put everything back together and test it again. You might have fixed it without knowing and you can buy a bag of Tootsie Pops to celebrate.