Electrical Diagnostic Procedural Lists [closed]

Post your general/specific Testing/Diagnostics Procedural Lists for Automotive Electrical Systems.

These procedures are intended to target vehicles with modern 12V systems.

The format of the site allows for each answer to have it's own separate thread, so each answer could be a procedure, and any information to add to said procedure can be a comment in that thread. Is there a better way to do this without posting it as a question?

Users would then be able to link to said procedure, which would reduce the repetitiveness of answers on break fix questions.

• You need to plan for a lot more answers... if you know how to use a meter... as per the comment I made to your previous question. What about the resistance ranges? The current ranges and safety issues? Testing diodes (used in alternators for example), testing capacitance? Frequency? Apr 20, 2018 at 13:17
• @SolarMike I am hoping for a lot of answers.=] Apr 20, 2018 at 13:45
• Sorry, but as this stands it's way too broad - I think it'd be better to post a number of more specific questions - Automotive Electrical Systems is a huge area to try and cover in one thing, covering everything from 6v analogue positive-earth right through to the latest canbus type things..
– Nick C
Apr 20, 2018 at 13:56
• @NickC it's intended to be a list/wiki to allow for reference. It's my intention that it be as broad as possible. Apr 20, 2018 at 14:00
• " It's my intention that it be as broad as possible" which is exactly why it was closed!
– Moab
Apr 20, 2018 at 14:08

There is this Guide, from /u/waynep712222 on Reddit, on Voltage Drop Testing:

How to Test Your Car Battery's Charge Using a Multimeter

1. First, set your voltmeter to 20 DC volts.

2. Touch the negative (black) battery terminal with the negative (black) meter probe.

3. Touch the positive (red) battery terminal with the positive (red) meter probe.

4. Ask an assistant to turn on the headlights to provide the battery with a light load.

5. Check your voltmeter reading, at a temperature of around 70°F (26.6°C) (+/- ~10°F):

• A reading of about 12.5 volts or higher means your battery has a good charge.
• A reading of about 12.3 volts means your battery is about 75% charged.
• A reading of 11.8 volts or lower means your battery is 25% or less charged.
• This is not always true - a battery can show 12.5 volts but have a damaged cell and not be able to deliver the power so the car won’t start... you need to check answers you post... Apr 20, 2018 at 13:20
• @SolarMike please feel free to post a complete procedure which is "more" correct for checking your batteries charge level, and any other procedural lists you might have/wish to contribute. Apr 20, 2018 at 13:41
• If I had the time to write a complete procedure with all the necessary info, knowledge, tips and tricks - I would publish it myself, not post it on here.... Apr 20, 2018 at 13:51
• @SolarMike I provided two answers as examples of what should be here. Things like the procedure checking an O2 sensor for another example, aren't any longer than the comments you've already posted. I realize that these procedures aren't common knowledge, which is the benefit of assembling a list of them here. Apr 20, 2018 at 15:07
• @SolarMike It's an example. It was copy pasta, anyway. I didn't throw you under the bus when you posted incorrect answers. Apr 20, 2018 at 15:39