Timer completely dead (no power / no display)
The timer shows no signs of life — no display, no LED, no output activity — so nothing it controls will ever operate.
Safety first
A dead timer can leave its output in either state. Confirm what it controls and whether that's safe before restoring power.
Isolate, lock out / tag out, and prove dead before working unless a live test is specifically required, authorised, and carried out under proper supervision. Always follow local regulations, your site procedures, and the equipment manufacturer's documentation.
Full detail — causes, the why, and common mistakes.
Likely causes
Ranked from most to least likely.
- 1
No supply to the timer
Most likelyThe timer isn't getting its supply — open upstream, blown control fuse, or a wiring fault.
- 2
Wired to the wrong terminals
#2Supply landed on the wrong terminals (some timers have separate supply and trigger inputs).
- 3
Wrong supply voltage
#3A timer fed the wrong voltage won't power up (or has been damaged).
- 4
Failed timer
Least likelyThe timer itself has failed internally.
Reports are saved on this device to reflect what you actually find.
Testing sequence
Work through one test at a time. Expected reading and what each result means.
Measure for the rated supply voltage at the timer's supply terminals.
Rated supply present at the correct terminals.
Powered but dead — suspect wrong terminals/voltage or a failed timer.
No supply — trace back (fuse, upstream, wiring).
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
Timer dead
→ step 2 - 2decision
Is rated supply present at the supply terminals?
Yes→ step 3No→ step 4 - 3decision
Are the terminals and voltage correct?
Yes→ step 5No→ step 6 - 4result
No supply — trace back (fuse/upstream/wiring).
- 5result
Timer failed — replace it.
- 6result
Wrong terminals/voltage — correct it.
Common mistakes apprentices make
- Landing supply on the trigger terminals instead of the supply terminals.
- Feeding the wrong voltage to the timer.
- Not tracing a blown control fuse upstream.
- Replacing the timer before confirming it actually has supply.
When to stop & escalate
If a control fuse feeding the timer keeps blowing, find the fault rather than replacing it repeatedly. Confirm the correct timer voltage against the design.
If you're past your competence, authorisation, or the safe limits of the job — stop and hand it on. There's no fault worth getting hurt over.
Related faults
Timer relay not switching its output
A timer relay is powered but its output contact never changes state — the delayed action (start, changeover, stop) never happens, or it switches at the wrong time.
No control voltage in the panel
Nothing in the control circuit will operate — contactors won't pull in, indicators are dead, the PLC may be off. The control voltage that should be there simply isn't.
Timer behaving as the wrong type (on-delay vs off-delay)
The timer switches at the wrong point in the sequence because it's acting as the wrong function — on-delay where off-delay is needed, single-shot where cyclic is needed, and so on.