Aggressive Method (Skilled Technician)
- Manage trailer brake application using the manual slide to seat brake components without lock-up.
- Verify heat generation using standard methods following a sustained half-mile drag.
- Recognize conditions requiring a stop and qualified review before a burnishing test.
- Brake Controller — Set GAIN to max and utilize the manual slide to apply trailer brakes independently of the tow vehicle.
- Tow Vehicle — Maintain speeds of 60–70 mph while overcoming trailer brake drag during the procedure.
- Temperature Gun/IR Thermometer — Check for heat at the wheels as specified in the standard method after the drag period.
How It Works
Aggressive Friction Seating
The aggressive method utilizes high-speed drag to burnish the drum and shoe surfaces. By maintaining a speed of 60–70 mph while applying the brakes for one-half mile, the technician generates the heat and friction necessary to seat new components quickly.
Controlled Drag vs. Lock-up
Application must be performed with the trailer brake slide while holding vehicle speed. The goal is consistent friction; locking the wheels must be avoided to prevent flat-spotting tires and ensuring even heat distribution across the drum surface.
Environmental Safety Requirements
Due to the speeds and heat involved, this procedure requires specific conditions: dry pavement, low-traffic areas, and strict adherence to posted speed limits to ensure safety during the high-load drag phase.
Interpret heat as evidence, not proof
This skilled-technician source method is planning material, not authorization for an unsupervised road test. Review the complete source and the standard-method heat check with qualified supervision. A cold brake requires electrical and adjustment diagnosis rather than simply assuming more brake drag is the solution.
Step-by-Step Procedure
0/5 doneDiagnostic Chart
| Symptom | Check | Spec / Expected | Likely cause & fix |
|---|---|---|---|
| Insufficient heat generated after one-half mile drag. | Verify that the brake controller GAIN was set to max and the slide was fully engaged without locking the wheels. | Per the applicable manual | GAIN was not set to maximum or the manual slide was not held for the full one-half mile duration. Basis: Lippert TI-086 Electric Drum Brake Break-In Period (Rev 08.13.2019) |
| Trailer tires flat-spotted or skidding during procedure. | Observe brake behavior; ensure brakes are applied only to the point of heavy drag, not lock-up. | Per the applicable manual | Excessive manual slide application or low-traction road conditions causing wheel lock-up. Basis: Lippert TI-086 Electric Drum Brake Break-In Period (Rev 08.13.2019) |
| Safe test conditions or qualified supervision are unavailable. | Review the complete source method and test conditions with the responsible qualified technician. | Do not proceed without the applicable safe conditions and authorization. | The source-specific test is not appropriate for the current conditions. Basis: General shop practice — test planning and supervision |
At the Bay: Diagnose the Case
CASE 1 / 3
Insufficient heat generated after one-half mile drag.
- Test
- Compare
- Correct
Select the next check
Basis: Lippert TI-086 Electric Drum Brake Break-In Period (Rev 08.13.2019). A likely cause is a hypothesis; confirm it with the applicable service procedure before repair.
Common Bay Mistakes
- ✕ Exceeding posted speed limits while attempting the 60–70 mph range.
- ✕ Applying brakes until they lock up rather than maintaining a drag.
- ✕ Attempting the procedure in wet or high-traffic conditions.
- ✕ Failing to set the GAIN to maximum before starting the high-speed run.
- ✕ Neglecting to pull over and perform the heat check immediately after the half-mile drag.
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 #9107B Electric Brake Force Meter
Plugs into the truck's 7-way socket on a 25 ft cable; simulates a trailer load and shows controller output on 10 blue LEDs
🛠 Equip your bay for this test →Symptom: Customer wants the truck checked before buying a trailer.
Spec limits used
- 1–10, each 1.0–1.5 V — Gain LEDs (IPA #9107B manual, p.5)
- 15 s — Max time holding brake pedal (IPA #9107B manual, p.4)
- set-up step 5 — Connect the 9-pin only after the engine is running (IPA #9107B manual, p.3)
- hold brake pedal during ECU detection — 2016–2017 'Trailer Connected' not shown (IPA #9107B manual, p.3)
- faulty brake control module or relay — ECU light never lights on a vehicle with a controller (IPA #9107B manual, p.5)
Simulated readings for practice. Always follow the manufacturer's procedure and values on a real trailer.
Source: Lippert TI-086 Electric Drum Brake Break-In Period (Rev 08.13.2019) — 2