Voltage-drop testing properly
The cable looks perfect and continuity says it is good, but the starter still cranks slowly.
What this lesson covers
CORE TEACHING Difference between continuity and loaded voltage drop; positive-side drop; ground-side drop; connection resistance; mV vs V; testing while the circuit is working. PRACTICAL DEMONSTRATIONS AND TESTS Battery positive post to starter B+ while cranking; starter case to battery negative while cranking; test across a corroded terminal before/after cleaning. ADVANCED / SCAN TOOL LAYER Use current clamp alongside voltage drop to relate current demand to losses. Scope capture of cranking voltage can be an optional advanced insert. KEY DIAGNOSTIC QUESTIONS Where should voltage be used? Where is it being lost? Is the loss on positive or negative side? MUST-COVER CHECKPOINTS Circuit must be loaded; positive side; ground side; connection-by-connection split; compare post-to-terminal; retest after repair.
What you will be able to do
The cable looks perfect and continuity says it is good, but the starter still cranks slowly.
Where it sits in the programme
- Builds on
- Lesson 3: Grounds and bad earths
- Feeds into
- Lesson 5: Multimeter use without blowing it up