Two test modes, one important distinction
The original GoTech article describes an engine-off test that uses vacuum developing as the system cools, and an engine-running test that uses purge to draw vacuum. In the latter, the controller evaluates switch reopening and vacuum decay. These are descriptions of the article’s system, not a calibration shared by every Chrysler, Dodge, Jeep, Ram or Fiat.
| Mode in the source | What creates vacuum | What the source describes observing |
|---|---|---|
| Engine off | Cooling of the sealed system. | ESIM switch response. |
| Engine running | Purge operation. | Switch response and subsequent decay behavior. |
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Match the explanation to the vehicle
Confirm the system diagram, required operating conditions and exact monitor description. The source does not establish verified thresholds, timing, wiring or application coverage for your vehicle.
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Sources, review and limits
Prepared by GoTech with AI assistance. Source wording and the bounded educational interpretation were checked in two reasoning passes by the same assistant. Technician review is pending; vehicle-specific service information and visual details have not been independently verified. Original source files remain unchanged.
- Two test modes, one important distinction
- Saved GoTech ESIM article, published 2022-06-01. Switch thresholds, timing and vehicle coverage remain unverified. Original GoTech article
About older links to this guide
This guide has been rewritten around the available source evidence. An older section link may land here; use “In this guide” above to find the revised explanation. Original source files are retained in GoTech’s review history.