Find the missing evidence in a control sequence
Use an original control-state table and time-aligned input/output records to find the last supported transition, distinguish a missing proof from its unknown cause, and plan a bounded next step.
The short version
- A request, an output command and the physical condition it represents are separate evidence.
- Locate the first unmet transition using the matched state table and time-aligned records.
- Do not bypass a proof input or name a failed part just because the sequence stopped.
Read a state table with the circuit
Our fictional RPH-1 heat trainer has request R, blower command B, airflow-proof input P and heating permission H. It is not an OEM furnace.
The original table defines the sequence for this exercise. It does not supply a field timing, jumper procedure or gas-appliance service instruction.
Follow the request circuit and the state table together. Wire locations alone do not explain when the controller expects a change.
| Original trainer label | Role |
|---|---|
| R | Request input |
| B | Blower command |
| P | Airflow-proof input |
| H | Heating permission |
Separate the transitions
At idle, R is off and H is off. With a valid R request, the trainer issues B.
After the supplied airflow proof P becomes active, the trainer permits H. Without P, H remains off.
These are declared virtual rules. A real controller may use a different sequence, checks, delays or lockouts; use its identified documentation.
Read one event rather than a mixed timeline
Run H records request active and source 12.40 V at the controller pair. B becomes active, and a supplied observation says the blower turns.
P remains inactive throughout this captured event. H remains off, matching the original table.
Do not combine P from yesterday with H from today. Preserve run identity, condition and the point each record describes.
| Supplied record | Meaning |
|---|---|
| Run H source | 12.40 V at controller pair |
| R / B | Active / active |
| Blower observation | Turning |
| P / H | Inactive / off |
A proof signal is not the physical condition itself
An inactive P record shows that the controller has not received the declared proof. It does not by itself tell you why.
Insufficient physical airflow, a sensing problem, a connection issue or an incorrect reference could require different evidence. This file has not separated them.
The fact that a blower turns does not measure the airflow condition. Likewise, a signal change alone is not a complete physical safety verification.
| Supplied record | Meaning |
|---|---|
| Observed | Blower turns |
| Recorded input | P inactive |
| Established | Required proof absent at this point |
| Still open | Physical condition or signal-path cause |
Choose a question that separates possibilities
The next useful request asks for the applicable procedure and the missing comparison between the physical condition, sensing device and controller input.
Do not approve a board, order a proof switch or bridge the input because H is off. Those actions assume a cause or defeat a condition.
The desk case accepts a handoff that names the gap and leaves the repair decision open. That is a complete reasoning outcome, not an unfinished guess.
| Supplied record | Meaning |
|---|---|
| Known boundary | Before proof-to-permission transition |
| Missing evidence | Condition versus signal path |
| Wrong shortcut | Bypass or speculative part |
| Supported decision | Qualified diagnostic handoff |
Transfer without memorizing the answer
Run J differs: R is inactive, B is off, P is inactive and H is off. Which transition is now first unsupported?
The request is missing. Repeating the Run H proof-input investigation would skip the earlier missing condition.
A third run with all inputs present but an absent output would pose another question. The state table locates the question; measurements must establish the cause.
| Supplied record | Meaning |
|---|---|
| Run H | R active; P missing |
| Run J | R missing |
| Different next question | Request path versus proof path |
| Avoid | Same repair for every no-heat case |
Keep later evidence tied to the repair scope
A later supplied file may describe a qualified repair and a comparable complete sequence. Read that file as new evidence, not as proof you already had.
Record exactly which condition was reproduced and which transitions were observed. A single simulated run is not a blanket field release.
Use the proof activity to compare inputs and outputs, then solve the case without turning an unknown cause into a named component.
Turn a diagram into a defensible next decision
Match the equipment and reference, identify connector views, trace the complete circuit, and name the meter pair and condition.
Then combine that circuit evidence with the stated sequence. Separate request, command, physical observation and returned proof.
When the cause remains unknown, a precise evidence request is stronger than a confident part guess. This path remains desk training, not hands-on authorization.
Shop tip
Josh: Name the last transition the records support, then the evidence needed for the next one.
Where this comes from
- OMRON General Purpose Relays: Introduction; Undated live manufacturer page; no revision shown; HTML sections What Is a Relay and Structure and Operating Principle; checked 2026-11-04. Scope: Mechanical relay coil/contact distinction only. No rating, pinout or replacement recommendation for an RV relay. https://www.ia.omron.com/support/guide/36/introduction.html
- Fluke 110/113/114/115/117 Users Manual; March 2020; printed 2,4,7-9 (PDF 6,8,11-13), functions, terminals, resistance, voltage and current warnings; checked 2026-11-04. Scope: Distinguish the meter function, input and measurement pair. No live-equipment access, isolation or capacitor procedure is taught. https://media.fluke.com/5e1db354-3a6e-49cf-9edd-b10800c0e608_original%20file.pdf
- Original Rigprobe teaching examples, 2026-11-04. Identifiers, diagrams, connector layouts, timings and readings are invented problem data, not OEM drawings, specifications or universal acceptance limits.
Try it on a service call
Put the lesson to work on a hands-on troubleshooting case.