The machine initializes, but closing the operator door produces S158 with the text hi res.meas.sys. input alarm. The same installation also reports E01 for low lubrication-pressure-switch status; earlier intermittent door events produced S153 or E130. Follow the signal from the door mechanism through the interlock and enable chain before condemning the spindle drive.
Where does the signal path stop?
Closing the door creates a physical state change at the door actuator and interlock. That state passes through the machine wiring and safety/control chain. If all required permissives become valid, the control can enable drives and begin monitoring measuring-system inputs under operating conditions.
The timing matters: initialization completes with the door open, and S158 appears only when the door closes. That makes the transition into the enabled state the diagnostic trigger. It does not identify the spindle drive as the failed component. A worn interlock, disturbed wiring, missing permissive, measuring-system fault, drive fault, or power-supply disturbance can all become visible at that transition.
Check before proceeding: repeat the sequence without moving any other mechanism. Record whether the alarm occurs at the instant the door actuator changes state, after a contactor operates, or when a drive begins enabling.
Is the door mechanism completing its full travel?
Layer one first. Isolate machine power using the established lockout procedure, then inspect the operator-door actuator, interlock body, mounting hardware, cable, connectors, and moving linkage. Look for loose fasteners, misalignment, damaged conduit, contamination, bent brackets, or an actuator that reaches the switch inconsistently.
Intermittent S153 and E130 events had already occurred while opening or closing the door. That history raises the priority of the door mechanism and its wiring. An automatic tool-changer door also previously failed to open completely and drove against its obstruction with maximum force. Inspect the affected door area and nearby cable routes for displacement or impact damage before testing electronic assemblies.
One reported candidate in a similar safety-switch investigation was labeled 16k1, but the identifier was not confirmed for this machine. Use the electrical drawings and cabinet labels to identify the actual operator-door and rear safety devices; never substitute an assumed device number.
Do not hold, jumper, or bypass a safety contact to keep the machine running. Manual operation of a de-energized switch may expose sticking, but it neither proves correct alignment under load nor validates the safety function.
Check before proceeding: verify that every actuator reaches its normal seated position smoothly and that the corresponding device changes state repeatably without manipulating the wiring.
Does the interlock state reach the control?
Open the control’s diagnostic or input-status display and locate the door-related signals using the machine electrical documentation. Observe the state with the door fully open, during travel, and fully closed. A physical switch can click while its electrical signal fails to reach the input because of a worn contact, broken conductor, loose terminal, failed intermediate device, or missing supply.
| Observed behavior | Most direct cause class | Next check |
|---|---|---|
| Input never changes | Actuator, switch, supply, conductor, or input-channel problem | Trace the circuit from the field device toward the control |
| Input flickers near the closed position | Misalignment, worn contact, vibration, or intermittent wiring | Check mechanical overtravel and continuity through normal door motion |
Input changes cleanly, then S158 appears |
Downstream permissive, drive-enable, power, or measuring-system problem | Follow the enable sequence and identify the first status that fails |
S150 and S158 appear immediately at power-up |
Fault exists before a door transition | Start with supply, diagnostics, connectors, and measuring-system readiness |
Where the circuit passes through relays or safety-control elements, compare the input and output states at each hop. Qualified personnel can measure voltage at the documented terminals with the specified test equipment; use the drawing’s nominal value rather than assuming a control voltage.
Check before proceeding: prove that the commanded door state arrives cleanly at the control and that the next device in the chain changes state once, without chatter.
Is E01 blocking the enable sequence?
E01 identifies a low state from the lubrication pressure switch. Treat that signal as an active fault, not as supporting evidence for a failed spindle drive. A controller may withhold a motion permissive when lubrication status is invalid, and the resulting enable sequence can expose additional alarms.
- Check the lubricant level, visible leakage, damaged lines, and pump operation using the machine service procedure.
- Observe the lubrication pressure-switch input during a commanded lubrication cycle.
- Determine whether pressure is physically absent or the switch circuit merely remains low.
- If pressure develops but the input stays low, trace the switch, connector, cable, and input channel.
- If pressure does not develop, diagnose the lubrication system before requesting drive enable.
Do not adjust or replace the pressure switch solely to clear E01. Confirm actual lubrication delivery first; masking a genuine low-pressure condition can damage lubricated components.
Check before proceeding: verify both physical lubrication delivery and a stable, correct pressure-switch state at the control.
What changes electrically when the door closes?
Once the door chain is accepted, the control may energize contactors, release inhibits, enable a drive, or begin validating a high-resolution measuring input. A weak supply, oxidized connector, marginal shield termination, or failing feedback channel can remain quiet while disabled and fault as soon as that transition occurs.
Use the event sequence and indicator states to identify the first downstream change. Listen for contactor operation only as a timing reference; confirm the result from documented status signals. Inspect relevant drive and measuring-system connectors with power isolated. Check for loose locking hardware, contamination, damaged pins, cable strain, and disturbed shielding. Do not disconnect or reseat feedback connectors while energized.
| Alarm timing | Diagnostic priority | Interpretation |
|---|---|---|
| Exactly as the door input changes | Door circuit and safety-chain transition | The state change itself is unstable or rejected |
| When an enable output changes | Enabled device, supply rail, contactor, and feedback readiness | The downstream subsystem fails its operational check |
| Immediately after startup, before door motion | Persistent supply, connection, drive, or measuring-input fault | The door is no longer required to reproduce the condition |
| Only after mechanical motion begins | Cable movement, encoder/measuring input, bearing, or mechanical load | Motion or vibration is required to reveal the defect |
Check before proceeding: identify one specific electrical event that immediately precedes S158; if no event precedes it, return to the input-state trace.
How should the measuring system and spindle drive be separated?
The alarm text points to a high-resolution measuring-system input, but the machine documentation must identify which axis, spindle, or channel owns that input. Read the complete diagnostic display, drive indicators, and any channel designation before removing the spindle drive.
- Record every active alarm in order, including
S158,E01, and any simultaneousS150,S153, orE130. - Use the electrical drawings to map the named measuring input to its cable, interface, and drive or control module.
- With power isolated, inspect both ends of that feedback connection and the full accessible cable path.
- Check whether the input reports a valid stationary position before enable and whether its status changes when enable is requested.
- Read the drive’s own diagnostic indication. A control alarm alone does not prove that the power section has failed.
A separate DMU50V case associated an S173+ alarm with a bad upper bearing. That code and failure must not be transferred to S158. Investigate bearings when the machine provides matching mechanical evidence such as abnormal noise, rough rotation, heat, runout, or a motion-dependent signal failure.
Check before proceeding: establish whether the measuring input is absent before enable, disappears during enable, or fails only with mechanical motion.
When is drive removal justified?
Remove the drive for repair only after the fault boundary reaches the module. The case is strong when its documented supplies and incoming enables are correct, external connectors and feedback wiring pass inspection, required permissives remain valid, and the module’s own diagnostics identify an internal failure.
The case is weak when moving the door changes the alarm, an interlock input chatters, E01 remains active, a supply collapses during enable, or the measuring-system cable has not been checked. Shipping the drive under those conditions can return a serviceable unit while leaving the actual fault in the machine.
- Save the alarm sequence and diagnostic states.
- Mark and photograph connector positions before removal.
- Record module identification directly from its label; do not infer it from the machine model.
- Provide the repair facility with the exact trigger: startup, door closure, enable transition, or motion.
Check before proceeding: confirm that the fault remains assigned to the drive after the door chain, lubrication permissive, supply, measuring-system cable, and external connections have passed their checks.
How do you verify the repair end to end?
- Start with the machine de-energized and restore all guards, connectors, and safety devices to their documented operating condition.
- Power up and capture the alarm list before acknowledging anything.
- Confirm that
E01is absent and that the lubrication pressure-switch state changes correctly during its cycle. - Observe the door input while opening and closing the door several times; require one clean transition in each direction with no flicker.
- Initialize the machine and close the door while monitoring the safety-chain, enable, drive, and measuring-input states.
- Confirm that
S158,S153,E130, andS150do not return during the sequence in which they previously appeared. - Run only the machine builder’s permitted commissioning motion, then verify that the measuring position remains valid while stationary and during motion.
Check: accept the repair only when the door state reaches the control cleanly, lubrication status is valid, the drive enables normally, the measuring input remains valid, and the complete startup-to-motion sequence finishes without the recorded alarms.
FAQ
Can I bypass the DMU50V door switch to test S158?
No. Observe the documented input state and trace the circuit with the machine in a controlled service condition. A bypass defeats a safety function and can also hide contact chatter or actuator misalignment.
Does S158 prove that the spindle drive is bad?
No. S158 reports a high-resolution measuring-system input alarm. Check the door chain, permissives, supplies, feedback connections, and the drive’s own diagnostics before assigning the fault to the drive.
Can E01 cause the drives to remain disabled?
A low lubrication-pressure-switch state can block a required motion permissive. Prove actual lubrication delivery and verify the switch state at the control before diagnosing the drive-enable path.
Does a previous S153 or E130 alarm point to the door switch?
When those alarms occur during door movement, inspect the actuator, alignment, switch state, and wiring first. Use the diagnostic input display to prove whether the signal changes cleanly rather than replacing the switch from the code alone.
Can I verify the fix without removing the spindle drive?
Yes. Repeat the original startup and door-closing sequence while monitoring the interlock, lubrication permissive, enable state, and measuring input; then complete the permitted commissioning motion and confirm that none of the recorded alarms returns.