March 1, 2022 by Jake Schell
More decades ago than I care to remember, some movie or folklore led me to start panning for gold in the dirt road outside our home. Slushing a pan full of dirt around in a pan with water from the garden hose rather quickly revealed the road to be a mother-load of GOLD.
The bright flecks floating to the top of the dirt in the pan glistened up at me in the sunlight. Carefully, I scooped the gold off the dirt and into my jar. As my gold dried, it turned black. No longer sure about this gold, I sought out the expertise of a higher authority, my Dad. With a chuckle he told me that it wasn’t gold at all but fool’s gold, or iron pyrite. My illusion as a rich gold miner quickly evaporated. “But how do you tell the difference between fool’s gold and gold?” I remember asking in despair. My Dad responded, “They test it.”
Spring forward a few decades. A service truck comes into the shop with a transmission shifting issue. A quick check reveals several shift solenoid low voltage codes. Going through the preliminary electrical diagnostic checks fail to identify what or where the low voltage condition originates.
I clear out the codes and take the truck for a drive. Sure enough, before long the problem happens again. Clearing the codes again, I monitor the voltage to the shift solenoids. Both solenoids operate correctly – cycling on and off with the corresponding gear – at least until the air conditioning cycled. Then the voltage dropped, and the low voltage codes reset.
The problem source was narrowing. Arriving back at the shop, I started looking at the wiring to the recently installed air conditioning system. Whoever installed the air conditioning system found a wire with key-on power and tapped into it to power the air conditioning compressor clutch.
While the circuit voltage provided enough power to illuminate a test-light, it was not enough to power the transmission shift solenoids and the compressor clutch. Finding a hot wire under the dash can be fool’s gold; it looks good but it’s really just creating a new problem.
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About the Author
Jake Schell
Jake Schell is the Associate Product Manager for Mitchell 1’s commercial vehicle product line. He has been with Mitchell 1 since 2001. Prior to coming to Mitchell 1, Jake spent 20 years as a technician, with Chevrolet Master certification in the transmission category as well as ASE certifications in both car and truck.
2022 Owned and Managed by John Lopez - Mitchell 1 Independent Sales Representative - (504) 289-0953 - john.lopez@mitchell1repair.com