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July 19, 2026 4 min read

1. QUICK SPECIFICATIONS & BENCHMARKS MATRIX

Electrical System Benchmarks

  • Operating System Voltage (Battery Model):24V DC

  • Solenoid Valve Terminal Voltage: 21.4V - 25V DC(when handle lever is pulled)

  • Power Board MOS-FET Thermal Cutoff Limit:150 Celsius

  • Board Mounting Screw Torque:3 NM(Must apply thermal conductive paste to back plate)

  • Brush Motor Mounting Bolt Torque:  9 NM 

  • Brush Head Pivot Bolt Torque:23 NM

Motor Current Draw & Wear Limits Table

Component Test Condition Min Current Max Current Wear Threshold / Replacement Limit
24V DC Brush Motor

No Load (Brush Raised)

 

2 A

 

3.5 A

Carbon brush length< 8 MM
24V DC Brush Motor Light Load (Empty Tank)

 

7 A

 

9 A

Replace all 4 carbon brushes simultaneously

24V DC Brush Motor

Full Load (Full Tank, Standard Brush)

 

9 A

 

11 A

Cutoff threshold: > 15 A for 20 sec
24V DC Suction Motor

No Load (Tank Removed)

 

13 A

 

17 A

Carbon brush length< 6-8 mm
24V DC Suction Motor Overload Limit —

 

> 30 A

Cutoff threshold: > 30 A for 20 sec

2. DISPLAY DASHBOARD ALARM CODES & METER FLOWCHART

 

NOTE: Internal motor thermal trip, blown individual motor fuses, or severed motor power cablesdo not display dashboard error codes. 

                     DASHBOARD LED ERROR IDENTIFICATION
                                     │
    ┌───────────────────┬────────────┴───────┬───────────────────┐
    ▼                   ▼                    ▼                   ▼
2 FLASHES           2 FLASHES            4 FLASHES          FAST FLASHING
(Brush LED)         (Suction LED)        (Brush LED)        (Both LEDs)
    │                   │                    │                   │
Short Circuit /     Short Circuit /      Brush Motor         Power Board MOS-FET
Peak Current        Peak Current         Internal Thermal    Overheating
    │                   │                Protector Tripped   (>150°C)
    │                   │                    │                   │
    ├─► Check motor     ├─► Check motor      ├─► Check for       ├─► Allow 15 min
    │   wiring short.       wiring short.        motor binding.      cool-down.
    │                   │                    │                   │
    └─► Verify rotor    └─► Check fan        └─► Test continuity └─► Check current
         spins free.         rotates free.       on 4-pin purple-    draw on both
                                                 black wires.        motors.

Detailed Error Troubleshooting Steps

2 Quick Flashes — Brush Motor Short Circuit Protection

  1. Disconnect battery power.

  2. Rotate brush manually to ensure motor is not mechanically locked/jammed.

  3. Disconnect power harness from brush motor terminals.Check for continuity/short to frame.

  4. Test motor directly with isolated 24V source.If motor draws excessive peak current, inspect rotor/commutatoror replace motor assembly.

2 Slow Flashes — Motor Overload 

  • Brush Motor Limit: Exceeding 15 A for > 20 seconds

  • Suction Motor Limit: Exceeding 30 A for > 20 seconds

  • Fix Action: Check brush pad aggressiveness/friction on floor surface, inspect carbon brushes, and check for string/debris bound in the drive reduction gearbox.

4 Flashes — Brush Motor Thermal Protector Tripped

  1. Motor thermal cutout is aNormally Closed (NC) switch operating between80 - 110 degrees Celsius.

  2. Bench Check: Detach the 4-pin connector on the main harness and check continuity across the twopurple-black wires.

  3. If open-circuit while motor is cool, replace the internal thermal protector.

3. COMPONENT DIAGNOSTIC DECISION TREES

Tree A: Machine Completely Inoperative (No Display LEDs)

  1. Check Battery Voltage: Ensure voltage across main terminals is > 21.5V DC

  2. Check Fuse F1: Inspect 30A Main Fuse on battery model (8AFuse F1 on corded model).

  3. Verify Charger Lockout Relay: Disconnect battery charger bullet connectorsE1 and bridge harness connectorsE2 to bypass charger interlock relay.If control panel powers on, replace charger module.

  4. Check Ribbon Cable: Test 10-pole flat ribbon cable for continuity pin-to-pin between function board and power board.

 

Tree B: Solution / Water Flow Failure 

                          NO WATER AT BRUSH HEAD
                                     │
      ┌──────────────────────────────┴──────────────────────────────┐
      ▼                                                             ▼
[ SOLENOID CLICK AUDIBLE ]                             [ NO SOLENOID CLICK ]
      │                                                             │
      ├─► Clean inline solution filter (if equipped).               ├─► Verify 21.4V-25V DC across valve
      │                                                                 fast-on terminals when lever pulled.
      ├─► Flush solution dispensing cock under tank.                │
      │                                                             ├─► IF VOLTAGE PRESENT: Solenoid coil
      └─► Disassemble solenoid valve & clear diaphragm                  faulty or valve membrane seized.
          outlet hole E.                                                Replace solenoid coil/assembly.
                                                                    │
                                                                    └─► IF NO VOLTAGE: Test output from
                                                                        power board contact J3 / check 10-pole
                                                                        ribbon cable continuity.

4. POWER BOARD & CHARGER SERVICE PROTOCOL

Replacing the Power Control Card

  1. Thermal Dissipation Safety: Clean mounting plate thoroughly.Youmust apply a fresh layer of thermally conductive silicone paste to the back of the new power card prior to mounting.

  2. Torque Spec: Tighten all 4 board mounting boltsE to 3 NM.Do not over-torque.

Battery Charger DIP Switch Configuration (SW2)

When swapping battery chemistry, configure switchSW2 on the internal charger board: 

      EXIDE GEL (Default)           DISCOVER AGM                 LEAD-ACID (WET)
        [ SW2 Board ]               [ SW2 Board ]                [ SW2 Board ]
        ┌───────────┐               ┌───────────┐                ┌───────────┐
     1  │  ■  OFF   │            1  │  ■   ON   │             1  │  ■  OFF   │
     2  │  ■  OFF   │            2  │  ■   ON   │             2  │  ■  OFF   │
        └───────────┘               └───────────┘                └───────────┘

  • Confirmation Verification: Upon plugging AC power into wall, observe status LED:

    • 2 Green Flashes: Configured for Gel / AGM profile.

    • 2 Red Flashes: Configured for Wet / Lead-Acid profile.

Looking for Replacement Parts or Technical Support?

Whether you need replacement squeegee blades, brush motors, filters, or battery care supplies, keeping OEM-spec parts on hand ensures minimal downtime. Contact our service team or explore our catalog for exact-fit replacement parts for Tennant, Nobles, and other leading floor scrubber brands. Shop Tennant CS16 Parts