Tool Briefing confirmed both the battery and charging system were within specifications. 3 TEST FOR BATTERY DRAIN There are numerous ways to test for current draw (amperage) at the battery. You could install a tester set to read amperage wired in series to either the positive or negative side of the battery between the cable and the battery. You can use a DMM, and it is a good idea to install a 7.5-amp fuse and holder between the meter and the battery. This will allow the 7.5-amp fuse to blow before the fuse in the meter, saving you time and money. Using a DMM works, but may not be the most efficient. Other tools we have found very useful and easier are the ESI Fuse Buddy and the Cal-Van Tools Amp Hound 2. These tools can be installed in the same manner as a DMM, but provide a digital readout that allows amp readings of an individual circuit, right at the fuse. In this case we used the Amp Hound 2, which allows you to read amperage on any circuit without needing to install the tester in series. This is beneficial because in the case of checking for an overall battery drain, disconnecting the battery to install a tool in series will lose memory and requires you to allow time for computer and radio memory circuits to recharge before reading residual current draw. Our tests determined there was no current drain at this time (See Fig.1). 4 TEST ALL LIGHTING, FUSES AND RELAYS Since we are still looking for an unknown cause of an issue at this point, it is not a bad idea to test all of the fuses to see if there are any issues such as either blown or missing fuses. One of the easiest ways to test fuses is by using a Power Probe. We use the Power Probe IV, which gives both a visual and audible signal when either ground or voltage is present. The Power Probe IV also has a built-in voltage drop test that indicates if there is excess resistance in a circuit. All of the fuses tested okay, except for fuse 25 in the main fuse box under the hood. 52 PTEN MAY 2016 www.VehicleServicePros.com For more information on the Cal-Van Tools Amp Hound 2, visit VehicleServicePros.com/12117390 For more information on the Hopkins Tow Doctor Trailer Wire Harness Test Unit, No. 50928, visit VehicleServicePros.com/12202018 For more information on the Power Probe ECT2000 Smart Circuit Chaser, visit VehicleServicePros.com/10099489 Circle 194 on card, or enter at “e-inquiry” on VehicleServicePros.com With four models available from Electronic Specialties, the Fuse Buddy can be installed in the same manner as a DMM, but provide a digital readout that allows amp readings of an individual circuit, right at the fuse. Pictured here is the ESI Max Fuse Buddy, No. 315. For more information on this product, visit: VehicleServicePros.com/10103238 This fuse supplies power to the running (tail) lights for a trailer. We replaced the blown fuse for the trailer lights, and since we do not currently have the customer’s trailer, we installed the Hopkins Tow Doctor into the trailer connector. This tool allows you to check the vehicle circuitry from the driver seat by illuminating lights on the handheld unit, indicating the correct light is turning on when the circuit is activated. Keep in mind this tool is great for testing the continuity of the circuit, but not if the circuit can sustain the load that may be needed to operate multiple lamps, or activate the brakes on a trailer. The tester showed the trailer/truck connection was correct and the fuse did not blow, which indicates the issue with the blown fuse is most likely in the trailer, not the truck wiring. We also will check all of the lighting on the truck and other electrical components to verify functionality. This step will assure there are no other issues and may assist in the diagnosis of the original concern, a parasitic battery drain. All other components worked without issue. We again used the Amp Hound 2 to verify there was no parasitic drain that could have surfaced after energizing all of the components which showed no amp draw. Since we needed to recreate the customer’s concern it was necessary to suspend all testing until we could have the trailer as well as the truck. 5 PERFORM TESTS WITH TRAILER HOOKED TO VEHICLE We had the customer bring the trailer in immediately after driving it for a period of time to duplicate the conditions of the original concern. We repeated the amp draw test, this time we showed a 2-amp draw. Using the Amp Hound 2 on the individual fuses in the underhood fuse box, we found the fuse to the trailer brake relay/controller (fuse 6) was drawing current. We also noted the trailer running lamp fuse was blown again. To confirm we were on the right path of our diagnosis, we disconnected the trailer connector and still had a 2-amp draw (See Fig. 2). Tools Used Circle 192 on card, or enter at “e-inquiry” on VehicleServicePros.com Circle 193 on card, or enter at “e-inquiry” on VehicleServicePros.com Circle 195 on card, or enter at “e-inquiry” on VehicleServicePros.com
Professional_Tool_And_Equipment_News_May_2016
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