Automative

For any electrical component to work properly, it must receive the correct current flow. Low current to a light bulb, for example, makes the light dim. Low current to a compressor clutch coil reduces the magnetic field and may allow the clutch to slip or not engage at all. For proper current flow to exist, the circuit must have the correct source voltage applied, and be free of any “unwanted” resistance in the circuit. And the best way to test this is to measure voltage drop with the circuit “working”.

Here are the steps to take to perform a voltage drop test:

1. Connect your DVOM negative lead to the battery’s negative post.
2. Connect your DVOM positive lead to the battery’s positive post and measure its voltage. Record this reading.
3. Connect your DVOM positive lead to the positive side of the load being tested, as close to the load as possible.
4. Operate the circuit, and record your measurement.
5. Connect your DVOM positive lead to the negative side of the load being tested, as close to the load as possible.
6. Operate the circuit and record your measurement.

Let’s take a closer look at these steps. First, we want to test the integrity of the ENTIRE circuit so placing your test leads at the battery is a must. You can make an extension lead for your DVOM so you can always connect to the battery ground terminal with your negative meter lead. Second, it is important to know the source voltage available. If the battery is weak to start with, your circuit is already working with a handicap. Even better is to measure source voltage with the engine running, and use that as your baseline.

In the third step, you are making sure all that source voltage is arriving at its ultimate destination…the load. Getting as close to the load as possible insures you are testing the entire path. On the positive side of the load, you should read within 0.50 volts of your source voltage, i.e. if you started with 14.56 volts you should read no less than 14.06 volts. This applies to most basic circuits. If you are diagnosing a control module related circuit, you may want to look for even less than that.

In step #5, you are looking for unwanted guests robbing your load downstream. Remember, all the voltage potential should have been used by the load. If you get a voltage reading of 0.50v or more here, there is someone else at home stealing potential from the primary component. This unwanted source may be ultimately found way “downstream” of the load, maybe even at the battery connection itself. Even so, it will still cause the voltage reading at the load to be over 0.50v. This is due to the available voltage being split proportionally between the two, and tends to throw techs new to voltage drop testing off. Remember, current flow is instantaneous throughout the circuit. Again, in the case of module related circuits, a little less is better. Stay as close to the load as you can to make sure you check the entire ground path.
Remember, current flow is only going to happen with the circuit turned on and working. Don’t forget to operate the circuit when taking your measurements.

My Reading Is Out Of Range. Now What?

Experience is a guide here, as in all things. Typically, unwanted resistances are the result of poor grounds or poor connections, either in a harness connector or switch contact, and will result in an obvious, out of range measurement. To find the little unwanted guest, all you have to do is “backtrack” from your load back to the battery. Here, you will need to spend some time with a schematic for the circuit you are working on and use a little common sense. For example, if there are parallel branches on the circuit, are all branches affected? If so, focus on that section of wiring common to all. If not, focus on that section that is unique to the component you are diagnosing. Move back towards the battery at logical points (harness connections, switch contacts, splice points, etc.) until your DVOM reading is back to normal. That means you passed the unwanted guest and all you have left to do is narrow the search between your last two test points.

Some voltage measurement on the ground side of a working load is normal. If no ground exists at all, you will measure source voltage on both sides of the load. If the ground side measures 0.0 volts on the money, and the component is receiving correct source voltage, then the load likely has an internal open.

What if both sides of the load test just fine, but it still doesn’t work right? If you tested right at the load, there is only one area left untested…the load itself. In this case, you most likely have a failed component. A good example of this is a solenoid that is failed mechanically, not electrically.

Remember, too, to not take shortcuts in your initial tests. It is vitally important that you test the entire path the current is taking from and back to the battery. A common mistake is to use a chassis ground under the dash when testing inside the car. But don’t forget, that chassis ground point still has to make it back to the battery, typically through a few more connections, before the ground path is complete. That inoperative HVAC module could be simply a bad connection at the bulkhead connector or firewall ground eyelet, and you’ll miss it if you cut corners. Done properly, a voltage drop test will quickly isolate which side of the circuit has the problem, and save you diagnostic time in the process.

Automotive extended warranties should be a very important part of one’s budget. After the vehicle’s initial warranty expires it would be wise to extend it because unexpected breakdowns can be devastating for one’s finances. A warranty is collateral that is offered by the manufacturer or another insurance provider. This means that if the product or service fails you are entitled to have it repaired or replaced. Let’s look at some of the top providers for automotive extended warranties.

1. Mogi

Mogi is a very recent entrant into the market of insurance. With their technological advances in terms of web based protection and support, Mogi has become the convenient and reliable choice of many consumers. Mogi offers several coverage plans for new and used vehicles. Each plan is tailored to the specific needs of the customer at the lowest rates possible.

2. Warranty Direct

Warranty Direct is very popular due to its wide array of coverage plans at reasonable prices. With more of a track record than Mogi, Warranty Direct has been in the business for 30 years. In terms of reliability you will find no better automotive extended warranty among the other companies. Warranty Direct is one of the largest warranty companies in North America making it very appealing to buyers looking for a safe and reliable purchase.

3. CARCHEX

Another well-known name; CARCHEX provides several automotive extended warranties. Plans for new and used vehicles add to the diversity of this company.

4. Stop Repair Bills

Stop Repair Bills will cover almost any vehicle. Most of their customers have vehicles over 12 years old. This company’s boldness has earned it a household name for good reason.

5. U.S. Fidelis

U.S. Fidelis is one of the largest automotive extended warranty companies in the United States. U.S. Fidelis offers many economic plans for new vehicles. This provider is a wise choice for those looking for an established company.

6. U.S. Direct

U.S. Direct is another exclusive provider in the United States. This automotive extended warranty company boasts a solid track record and excellent customer service.

7. Fidelity Automotive

Fidelity provides extended warranties to both new and used cars. To go along with their coverage, Fidelity also offers excellent customer service with roadside assistance and repair.

8. Auto Protection

Auto Protection is smaller than the other providers; to compensate for this Auto Protection offers excellent customer service and makes their policies very clear.

9. Endurance Protection

Another small automotive extended warranty provider; Endurance Protection offers several incentives such as instant savings and roadside assistance.

10. Auto Service Warranty

Auto Service Warranty provides used and new automobile coverage. Automotive extended warranties are provided at very economical pricing.

If you need an online auto repair manual that can help you precisely fix your problem, the internet has an incredible amount of car care information. What you won’t find however, is a Chiltons or a Haynes auto repair manual, because they’re copyrighted material. You don’t need them anyway, because there are a lot of good car repair web sites with individual pages or articles that can solve your specific problem.

In fact, you’ll find articles on all kinds of car fix and vehicle maintenance topics, such as

auto body repairs automatic transmission replacement bleeding brakes car audio systems fix changing oil finding the causes for a bearing failure how to install a replacement ignition system how to upgrade an exhaust system troubleshooting car stalling troubleshooting car starting problems

and much more.

Here is a good place to search for vehicle fix manuals: Go to the search site at 10w40.com and type in the problem you want to solve – and the likelihood of finding the instructions you need is high. On this website you can also post your problem on an advice and discussion board, and get your problem solved almost instantly by an expert in this repair field or by an ordinary person who has experienced your problem and solved it already or might know where to go to get the answer you need. And it doesn’t cost you a cent.

There are many other good websites where you can get an online auto repair manual that will fit your needs. Go to Google.com and type in [the problem you want an answer to]+repair manuals, and you should find lots of valuable vehicle repair resources that might solve your problem.