Senior Diagnostic Technician
Marcus Holt
19
articles
Verified author
About
Fifteen years in automotive diagnostics, starting with warranty work at a Chevy dealer in Scottsdale — the kind of job where every comeback lands on your desk. Four years reading wiring diagrams before the coffee was hot, pulling ECM data on vehicles nobody else wanted to touch. Left the dealership in 2019, rented a bay in Tempe, and built an independent shop around the work most technicians avoid: electrical faults, intermittent failures, trucks and SUVs with gremlins buried deep in the body control modules. Trained at UTI Phoenix, ASE-certified across multiple categories including electrical systems and engine performance. The diagnostic approach here comes from the lift, not the textbook.
How to Find an Air Suspension Leak: Overnight Test, Soapy Water and Corner Isolation
Four tests in the order the dealers run them: the overnight height measurement with Mercedes 15 mm threshold, soapy water at the five places air gets out, a scan-tool hold per corner from the Ram procedure, and the moisture check that decides whether the compressor and valve block go too.
How to Test and Replace an Ambient Air Temperature Sensor
The outside temperature on the dash is the ambient air temperature sensor talking. Read the number it shows, rule out the display delay carmakers build in, then measure the circuit at the cluster before the sensor. Tesla, BMW, GM and Audi service documents as the examples.
Subaru “EyeSight Disabled” and “EyeSight Off Check Manual” Messages
Subaru shows EyeSight Disabled with a white temporary-stop indicator that clears itself, and EyeSight Off Check Manual with a yellow warning indicator that means a stored fault. The manual, five Subaru bulletins and two recalls separate glass, temperature, camera software, low voltage and the brake-pedal switch.
V2X and C-V2X Specs: Vehicle-to-Vehicle, Infrastructure and Road-Safety Communication
Published V2X figures with their sources: the 5.9 GHz band plan the FCC finalised in 2024, the 10 Hz, 300 m basic safety message, 3GPP latency targets for C-V2X, ETSI ITS-G5 channels and CAM rates, and what production cars in Europe and the US actually carry.
EU Vehicle Data Access: What Car Owners and Independent Repair Shops Can Access
What the EU Data Act and the type-approval regulation actually grant car owners and independent shops, article by article, against the Massachusetts and Maine laws, the federal REPAIR Act and the FTC order on GM.
Engine Coolant Temperature Sensor Location: Where It Sits and How to Find It
There is no single place to look: the sensor sits in the thermostat housing on one engine, the cylinder head on another, and MINI moved it into the upper hose entirely. Documented locations and how to find yours.
Bad Engine Coolant Temperature Sensor Symptoms
A wrong coolant temperature reading usually shows up as hard starting, rich running or a code, not as a temperature problem. Here is what separates the sensor from everything else that causes the same complaints.
How to Test, Clean and Replace an ABS Wheel Speed Sensor
Work out whether the sensor is passive or active before you touch a meter, because the wrong test produces a number that looks like a diagnosis. Then test, clean only what cleaning fixes, and get a seized sensor out without snapping it.