Alex Original recommends moderate tension on the belt.
Here’s the correct standard:

  • Stretch the belt tight enough that there is no visible sag between pulleys.
  • Then, check:
    • You should be able to press down on the belt with your finger about 5–7mm (about 1/4″) at the mid-span.
    • Do not over-tighten: the belt should NOT be guitar-string tight.
    • If belt is too tight, the motor will strain or cut torque detection.
    • If belt is too loose, the door won’t move consistently, especially uphill or on slight binds.

✅ Quick tip:
When the belt is properly adjusted, you should hear a light “whirring” noise from the belt moving under light load — no clunks, sags, or slack snapping sounds.

2. 🔒 Latch Does Not Engage at Door Close

This is a very common issue right after installing Alex ESD systems.

Here’s the likely causes (ranked):

Possible CauseExplanationFix
Latch alignment offElectric motor gets door near closed but not tight enough to trip the mechanical latch.Adjust the lock assembly position closer or re-check mounting slots.
Actuator cable slack or misadjustedThe cable connecting the ESD actuator to the factory door lock is too loose.Tighten/shorten the actuator cable at the adjuster bolt until it actively pulls at end of close cycle.
Belt tension wrongIf belt is too loose, door won’t push fully into striker latch at end of travel.Re-tension belt (see Step 1).
Microswitch incorrectly installed or pressed earlyMicroswitch inside door tells controller “closed” before it’s actually latched.Adjust microswitch lever or re-seat microswitch trigger points.

🧠 Real-World Installer Tip:

Tighten the actuator cable FIRST —
Then, only if still needed, nudge the latch mechanism closer to the door’s centerline.

If you only move the latch without fixing actuator tension, you’ll just mask the real issue.

📋 Step-by-Step Correction Plan:

  1. Recheck belt tension — tighten or loosen slightly as needed for ~5–7mm finger deflection.
  2. Adjust actuator cable tighter — until it slightly “pulls” when fully closed (not slack at resting position).
  3. Test door manually by hand closing — it should “click” solidly into latch.
  4. Adjust striker/latch plate if needed — move it slightly toward inside of van (2–3mm is often enough).
  5. Re-learn door travel in ESD system if latch engagement changes — (basic open/close programming cycle).

🎯 In short:

  • Belt = moderate, no sag, no over-tight tension.
  • Door latch = adjust cable first, then adjust latch position if needed.
  • If door moves but doesn’t “click” tight, the cable tension is almost always the real issue.