I haven’t read all the responses yet, and I am not able to at the moment. However, I did see this question and thought it would help to be more specific.
I am interested in having the ability to test electrical components of a car before I put the parts in (in the case of something like a radio), or troubleshooting a problem (such as an electric motor on an automatic window regulator).
I want this for two reasons:
I am restoring a car, and a number of parts that I find on the secondary market are worthless to me unless they work properly. The radio falls into this category, as does something like a horn, which cannot be tested without a power supply.
I am interested in maintaining my current vehicles, and having the ability to troubleshoot where the problem is why I want to have this set-up. For example, I recently had my defroster die. After doing some preliminary research and testing (checking the fuses, for example), I narrowed the problem to two major components. Either the blower motor was dead, or the resistor was bad.
Having the ability to check if the blower motor was the problem or not would have helped pinpoint the problem, and I would able to buy only the parts I needed for the repair.
I hope this helps. if not, let me know and I’ll try to answer the question more specifically. I don’t know what else I can say, other than list specific parts that I may/will need to test in the future, like the window regulator motor, or a power antenna motor.
As to HOW i am planning on testing it, that is part of my question. I figure if I have a proper power source and have it hooked up correctly, I could test the items by hooking up wires to the appropriate terminals. However, I don’t know much about electricity (other than very basic concepts), so I thought asking the TM could start me down the correct path.
I agree. If I don’t have to take a part out of the car, that is the preferred option.
But how would I go about that? Wouldn’t I have to have a portable power source to hook up on the blower motor?
I would unhook the car battery first, then hook up the portable power source to the blower motor, correct?
Maybe I am missing something basic and fundamental here, but I would think in order to test something like the blower motor, I would first need to remove the current power source (the car battery). Then, I would need to hook in an alternate power supply to see if the motor is working or not.
You use a meter to see if there is voltage at the connector.
If there is, the assumption is that it’s a good connection (until proven otherwise), so if the motor doesn’t work, it’s the motor that’s bad.
This tests all the wiring and switches up to the motor.
You can also use a meter to see if the voltage drops significantly when the motor is connected, which would suggest that it’s bad connection (or bad switch, etc.). You can then use the meter to figure where the high-resistance connection is in the chain.
For this circuit a 12V test light and maybe a voltmeter is all you need.
Hook the alligator clip to ground
Key on
Check both sides of the blower fuse (fuses can blow and NOT be obvious)
Assuming this is not an automatic climate system and has a switch with individual speeds (1-2-3-HI)
Go to the back of the switch assuming 4 fan speeds there will be 5 wires. With the switch off, and the key on one wire should have power
On low a second wire will have power
On speed 2 a different wire
On speed 3 a fourth wire will power up
On Hi the last wire will get power.
Assuming all of those are OK go to the resistor pack. The wires from speeds 1,2and 3 will lead to that with one wire leading out to the fan motor. Sticking the test light on the wire to the fan motor you should have a dim light in position 1, brighter in position 2, brighter in position 3, and full bright in Hi.
If you have power to the fan motor bad fan motor. If switch works but no power to motor bad resistor.
If it works in all speeds but Hi you would need to check the max fan relay which would need a wiring diagram.
If it’s an automatic climate control system I believe the diagnostics are beyond where I perceive your abilities to be.
I think there is enough advice to get me started. I am going to look for something that will permit a variable amount of power, like a couple of devices linked to in this thread. For the purposes of my restoration, I think this set up will cover most of my needs.
I am not comfortable using a battery with a charger. I have heard of batteries exploding and/or not behaving nicely if something is hooked up incorrectly. I don’t know enough about batteries to feel comfortable with working with a used, underpowered battery, even if I can pick one up for $20. I am sure this would work just fine for those who know what they are doing, but I need something that is straightforward, and will work the way I expect it to. The units linked to, which can provide between 5-12 v (give or take) will be the best direction for me to go.
As to testing items inside a car (like the blower motor I mentioned above), I think Rick’s explanation of how to test it before removing it will work. I was confused with how to test something without providing a power source… I wasn’t thinking of making sure the device is receiving the proper voltage, which can be checked easily with a test light and volt meter. I was thinking I would have to take the blower motor out and send power through it to remove the motor from the list of potentially failed parts. :smack: Rick’s way is much easier.
Thanks again for all the help and advice.
SFP
Follow-up:
In case anyone was wondering, the blower motor was NOT the problem. It was the resistor. I bought a new one, installed it, and it is running just as it should.