Once Again, Problems From Cheap Fuses! parts stores that your professional shop may be purchasing parts from! Even more bad news is the parasitic current draw test of using a mV voltage drop across each fuse to locate offending circuits is no longer a valid test with these fuses. As a matter of fact, you need to identify the presence of any of these knock off fuses before your customer 's wiring harnesses start having major melt downs. How do you identify these rogue fuses? Another update to this topic revolves around fuses themselves. Remember hearing about those knock off automotive fuses that were being sold by a particular discount DIY tool franchise? They were made in China and were super inexpensive. They had one major drawback though; they didn't blow when they were supposed to. One of those knock off fuses rated at 10 amps, for example, may actually withstand a partially shorted circuit drawing 30, 40 or more amps before it blows! Reports of wiring melting, vehicle fires, etc. weren't uncommon. The update on these knock off fuses contains more bad news. Their distribution has made its way past that discount tool store into some main stream auto Chart Courtesy PowerProbe 1. Knock Off Fuses Do NOT Have the Amperage Rating Stamped on Top (Fig. 12) 2. Knock Off Fuses DO Have Serrations on the Top of Fuse (Fig. 12) ■ Figure 13: This is a partial section of a multi page chart that has been around for years showing the measured mV of voltage drop (far left column) across a fuse's contacts. Follow the chart from left to right until you reach the size of the fuse you are measuring the voltage drop across. A Blue 15 amp mini fuse with a 0.1 mV voltage drop (key off after several minutes) would have a measured current draw of 22 mA. That's a bit high for a single fused circuit but still within specs if the entire vehicle's mA draw is not over 50 mA. Moving down the far left column to a measured mV voltage drop across the same fuse displaying 1.0 mV translates to 218 mA of battery parasitic current draw. This reading would then point you to a fused circuit that needs to have further diagnostics performed to see which item(s) on that circuit are drawing this excessive amount of current. All the charts are downloadable at http://info. powerprobe.com/fusechartsdownload June 2017 6 MACS Service Reportshttp://info.powerprobe.com/fusechartsdownload http://info.powerprobe.com/fusechartsdownload