Lesson 49In production35 min
Loaded circuit testing
Meter shows battery voltage. Connect the actual load and everything dies.
What this lesson covers
CORE TEACHING High-impedance meter; test lamp; substitute load; resistance under real current; voltage collapse. PRACTICAL DEMONSTRATIONS AND TESTS Measure suspect supply unloaded; connect lamp; observe collapse; trace drop toward source. ADVANCED / SCAN TOOL LAYER Scope voltage during load switching for transient drop. KEY DIAGNOSTIC QUESTIONS Can this circuit deliver current, not merely voltage? 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
Meter shows battery voltage. Connect the actual load and everything dies.
Where it sits in the programme
- Builds on
- Lesson 48: Test the connector before replacing the component
- Feeds into
- Lesson 50: Finding open circuits
More in Diagnostic Method
- 47Power–ground–signal: the default framework
- 48Test the connector before replacing the component
- 49Loaded circuit testing
- 50Finding open circuits
- 51Finding shorts to ground
- 52Finding shorts to positive and back-feeds
- 53Parasitic battery drains
- 54When pulling one fuse kills the drain
- 55ECUs and control modules
- 56The complete Voltzs diagnostic workflow