Breakaway Test Procedure
- Verify breakaway system functionality according to Cequent TB11-06.
- Observe safety limitations regarding breakaway switch activation duration.
- Identify mechanical and electrical factors that cause weak brake application during testing.
- Tow vehicle — Provide the hitch point and mobility required to perform a pull test on the trailer brakes.
- Battery charger — Ensure the breakaway battery is fully charged as required before beginning the test procedure.
- Voltmeter — Confirm the breakaway battery voltage status prior to system activation.
The breakaway battery must be fully charged before testing. Do not leave the pin pulled more than two minutes (Dexter).
How It Works
Prerequisite Battery State
The breakaway battery must be fully charged before testing begins. A low battery voltage can lead to weak brake application, providing a false indication of the system's mechanical health.
Switch Activation Limits
During the test, the pin is pulled to simulate a breakaway event. Per Dexter requirements, do not leave the pin pulled for more than two minutes to prevent potential damage to the system components.
Mechanical Verification
The pull test confirms that the electrical signal from the breakaway switch successfully translates into mechanical holding force. The wheels should rotate only slightly before the brakes lock to prevent free rolling.
Step-by-Step Procedure
0/6 doneDiagnostic Chart
| Symptom | Check | Spec / Expected | Likely cause & fix |
|---|---|---|---|
| Trailer rolls freely during the pull test. | Perform service on the breakaway system or trailer brakes and retest. | Wheels should rotate slightly, then brakes should hold so the trailer won't roll freely. | System failure, depleted battery, or brakes requiring mechanical adjustment. Basis: Cequent Technical Bulletin TB11-06 |
| Resistance required to pull the pin is significantly lower than expected. | Inspect the breakaway switch for physical damage or internal wear. | About 40 lb of pull. | Worn or damaged breakaway switch internal components. Basis: Cequent Technical Bulletin TB11-06 |
| Weak brake application during the pull test. | Verify brake adjustment, battery voltage, and trailer load status. | Per the applicable manual | Brakes out of adjustment, low breakaway battery voltage, or a heavily loaded trailer. Basis: Cequent Technical Bulletin TB11-06 |
At the Bay: Diagnose the Case
CASE 1 / 3
Trailer rolls freely during the pull test.
- Test
- Compare
- Correct
Select the next check
Basis: Cequent Technical Bulletin TB11-06. A likely cause is a hypothesis; confirm it with the applicable service procedure before repair.
Common Bay Mistakes
- ✕ Leaving the breakaway pin pulled for more than two minutes.
- ✕ Testing the system while the trailer is still electrically connected to the tow vehicle.
- ✕ Attempting the test with a partially discharged breakaway battery.
- ✕ Failing to reinsert the pin and reconnect the plug after testing.
- ✕ Pulling the pin at an angle instead of straight out of the switch.
Quick Check
Practice only — not scored.
Plan the Service Sequence
Planning practice only. Follow the applicable manufacturer's instructions, employer safety program and qualified supervision on real equipment.
Plan the first action. Compare the service steps with the bay mistakes.
Hands-on: Test Bench Practice
Symptom: Healthy trailer. Learn what good readings look like.
Tap a point to place the red probe.
Good system: ~12.6 V at pins, 3.2 Ω across a 12×2-inch magnet (unplugged), 3.0 A per magnet at 12 V full gain, and at least 10.5 V at the magnet — the chart values from the axle manuals.
Hands-on: Shop Test Equipment
IPA #9101 Light Ranger MUTT Trailer Tester
Battery-powered tester with a 7-way flat socket and rotary knob — powers one trailer circuit at a time, up to 10 A
🛠 Equip your bay for this test →Symptom: Pre-delivery inspection on a new utility trailer.
Spec limits used
- 10 A @ 12 V DC — Max output per circuit (IPA #9101/#9102 manual, p.5)
- 30 s — Thermal breaker cooldown (IPA #9101/#9102 manual, p.5)
- 11.5 V tester battery — Never operate below (IPA #9101/#9102 manual, p.6)
- 12.2 V — Verify battery charged to at least (IPA #9101/#9102 manual, p.10)
- battery on the trailer detected — Power LED on with knob OFF (IPA #9101/#9102 manual, p.6)
- 3.0 A each — Brake magnet current (warm) (Dexter magnet data (simulator basis))
Simulated readings for practice. Always follow the manufacturer's procedure and values on a real trailer.
Hands-on: Wire-Trace Overlay
Pin 2 · Blue
Electric brakes
- Left and right brake magnets
- Breakaway switch output
Check points
- Two brakes draw about 6.0 A (3.0 A per magnet) at 12 V full gain.
- Unplugged: 3.2 Ω per magnet; at least 10.5 V at each magnet under load.
Common failures
- Open magnet: about half the expected current and a pull to one side.
- Shorted magnet: very low resistance and controller overload.
- Wire chafed where it drops to the axle.
Colors shown are the most common RV harness colors; makers vary — always verify against the trailer's wiring diagram.
Source: Cequent Technical Bulletin TB11-06 — Testing Breakaway Systems (etrailer)