I would consider my electrical knowledge about average. I understand the basics about relays, voltage,resistance, reading electrical diagrams etc.
But I would like to increase my knowledge on how to test specific sensors, relays etc. The diagrams I have used in the past show me the compenents in the electrical system, but for instance a relay has many wires running into and out of it. How do I figure out which wire to test to see if the relay is working?
Is there a general rule for the colors of the wires?
In the past when testing a relay, I would have to ask someone else which wire to test. Sometimes the GM Service Manual is confusing to me on how to test the electrical components.

Are there any books or videos one would recommend to bring my knowledge above average?

Thanks in Advance/

 

First thing necessary is a VOM with a high impedance. Most digital models sold nowadays have this already. I use a Sears Craftsman. Most relays I have ever seen have a painted or stamped functional schematic directly on the relay. As long as you're up on your symbology, you can tell which pins are the coil for the relay and which pins are the contacts. If not, the repair manual schematic diagrams shows the pin-out(s).
The schematics in the manual also shows wiring color(s) and even shows the gauge of wire as well as circuit number (helpful when a circuit drawing starts on one page and continues on to another).
Unlike years past, the wiring diagrams currently in use in the repair manuals are broken down into "cells" (or seperate sections illustrated on one page at a time). Gone are the days of the multi-page full color foldout wiring diagrams. One thing that has remained pretty constant though is the use of the colors for basic ground (still black) and power (still either red or orange)
Although the basic electrical/electronic symbology are pretty much the same, I have spent a lot of time reading the electrical section(s) of the manual in order to get used to GMs terminologies (i.e. power cell, ground cell, etc), schematic flows and how the circuit number and component locations, connector locations (and pin-out as well) can be helpful in following a given circuit.
All I can say is, work with manual in order to better understand the methods and techniques GM uses. Once you use, and maybe practice a bit, such as using the connector locations, etc and then finding them, you will find it all starts to make pretty good sense after awhile.
HTH,
Robert

 

WHen checking anything electrical with the battery disconnected, use a volt-ohm meter that's analog. digital still doesn't get my hopes up that i will find the problem.
for energized systems, digital volt meter is the best. it's more accurate.
On checking relays with out the symbology, usually there are two pins, blades, etc. that either are stand alone, or are positioned within the other pins/blades. THe two that are different should be the coil and have resistance, maybe 250 ohms, or more, depending on the size and windings in the coil. The lower resistance, the bigger the coil windings or fewer of them. If the resistance is less than 150 ohms, the windings may have begun to short out internally.
some relays have two or three "relays or switches" in them where the contacts for them are usually normally open, normally closed, and a common. Relays that have multiple contacts are operating more than one circuit or item at the same time. for instance, one set of contacts disarms the ignition system with the key off, and say turns on or arms the alarm so that the alarm works with the key in the off position, but you can't arm the alarm with the key on.
pick a terminal, and the ones usually in a row are one "relay or switch"
and probably the middle one is the common. you will have to probe the terminals, but mostly, the common is on one end., but it can be in the middle also.
if you determine which is the coil, the coil wires in the relay are usually above ground, in that the case is usually plastic, and need an external ground. A lot of the newer relays have a diode built in so energizing it doesn't give you a "click" in your radio. If they have the diode, you must observe polarity. if no diode, then it doesn't matter which is positive and negative if it's in your hand, and not installed. but just for checkout purposes.

 

The reason I recommend a digital VOM is that nearly all that I have seen are of the high impedence (10 MegOhm and higher) type nowadays, which is really the more important thing than actual accuracy. It can be used to read very low signal voltages as well as the higher voltages in some circuits, without risk of inadvertently frying your solid state goodies in the electrical system (ROMs, etc) as well as being useful for continuity checking, etc without fearing the same thing. Unlike the past, the batteries contained in a test meter can supply enough current and/or voltage to damage or destroy some of the more sensitive solid state devices in use these days if one were to inadvertently attach the probes/test leads to the wrong spot.
HTH,
Robert

 

We are in the computer age, and most things contained within do not appreciate being hit by the batteries voltage contained within an old style analog meter. So unless you are absolutly sure that you are not going to send some strange stuff to a location you are not aware of, stay with a DVM.

 

Is there an internet resource for C5 electrical system? I could really use a diagram with all the components.