Why Is the Bomag BF 600 P-2 Screed Display Unresponsive After Startup?
Operators working with the Bomag BF 600 P-2 often encounter a blank or frozen screed display immediately after starting the machine. This issue typically originates from a voltage drop at the control unit, a blown fuse in the main electrical panel, or a loose connection at the CAN bus backbone. When the display does not respond, the paving screed cannot adjust mat thickness, extend wings, or monitor heating zones.
Begin troubleshooting by inspecting the 15-amp fuse labelled “CONTROL UNIT SCREED” located behind the left-side access panel. Use a multimeter to verify continuity; replace the fuse if open. Next, measure voltage at the display power input: it should read 12.0–12.6 V DC with the engine running. If voltage is below 11.5 V, check the alternator output and battery terminals for corrosion (clean using a wire brush).
For persistent issues, examine the CAN bus termination resistor. The resistor (120 ohms) is placed at the last device on the loop—often the left wing actuator. Disconnect the resistor and measure its value; replace if outside 118–122 ohms. A faulty resistor causes erratic communication, making the display appear dead. For additional electrical checks, refer to the Bomag BF 600 P-2 Daily Maintenance Checklist for Peak Performance guide for step-by-step fuse and relay inspection.
What Causes Intermittent Paving Width Control on the Bomag BF 600 P-2?
Intermittent width extension or retraction during paving operations points to a failing solonoid valve, damaged wire harness, or corroded connector pins at the screed extend sensor. The Bomag BF 600 P-2 uses a proportional control valve to adjust screed width from 2.5 m to 6.0 m. When the signal is interrupted, the screed may not respond or move jerkily.
Start by locating the width control solonoid valve under the rear guard near the hydraulic manifold. With a test light, probe the two wires at the valve connector while a second operator operates the width switch in the cab. If the test light blinks inconsistently, the issue lies upstream. Remove the connector and check for bent or corroded pins. Use electrical contact cleaner and dielectric grease to protect the terminals.
If the solonoid tests good, inspect the harness from the cab joystick to the valve. These wires run along the chassis, rubbing against sharp edges over time. Look for chafed insulation, especially near the pivot point of the operator platform. Repair damaged sections with heat-shrink butt connectors. For more insight on hydraulic component interactions, read the Bomag BF 600 P-2 Hydraulic System Maintenance: Essential Tips article.
How Do I Diagnose Short Circuits in the Bomag BF 600 P-2 Screed Harness?
Short circuits frequently appear after screen replacements or sensor swaps. The main harness, running from the junction box behind the cab to the screed, contains 24 wires for controls, heating, and sensors. A short to ground will blow a fuse, while a short to voltage can damage the control module. Symptoms include blown fuses on the “SCREED AUX” circuit or erratic warnings on the display.
Use the following systematic steps to locate the short:
- Disconnect all connectors at the screed (heater cables, extension sensors, and mat thickness potentiometer).
- With the engine off, set your multimeter to ohms and probe pin A1 (power) to chassis ground. A reading below 10 ohms indicates a short.
- Reconnect one connector at a time. When the reading drops sharply, the short is in that branch.
- Common failure points: the left extension sensor wire where it passes through the screed frame (chafing) and the mat thickness potentiometer connector (moisture ingress).
For persistent shorts, consider replacing the entire harness section. The cost of a new main harness for the Bomag BF 600 P-2 runs approximately £1,650 to £2,100, depending on the supplier. Yet, in many cases, a targeted repair using waterproof heat-shrink connectors (about £15 per kit) solves the issue. Pair this diagnostic with the Bomag BF 600 P-2 Screed Wear Parts Replacement Guide to keep the entire system in top condition.
Can Low Battery Voltage Affect the Bomag BF 600 P-2 Screed Performance?
Absolutely. The screed control system demands stable 12 V DC even under load. When the battery voltage drops below 11.0 V during cranking or idle, the electronic control unit (ECU) may reset, causing the screed to stop responding or display memory errors. The Bomag BF 600 P-2 uses a single 12 V battery rated at 110 Ah. After several seasons, capacity degradation accelerates, especially in colder climates.
Check the battery condition using a load tester. A healthy battery should hold above 10.5 V for 10 seconds under a 150 A load. If it fails, replace the battery (cost approx. £230–£320 at local dealers). Also examine the ground strap from the battery negative to the chassis: a corroded strap adds resistance, starving the screed electronics. Clean the connection points with a wire brush and tighten to 18 Nm.
Inspect the alternator output—should be 14.0–14.5 V at 1500 rpm. Weak alternators cause chronic low voltage, leading to intermittent screed freezing. Redress the alternator drive belt tension if squealing occurs. For a thorough check of related electrical components, consider the Bomag BF 600 P-2 Engine System Maintenance: A Comprehensive Guide.
| Symptom | Severity Level | Typical Repair Cost (GBP) | Common Cause |
|---|---|---|---|
| Display unresponsive after start | High | £80–£250 | Fuse or CAN bus resistor |
| Intermittent width control | Moderate | £60–£180 | Harness chafing or solonoid valve |
| Blown fuses repeatedly | High | £150–£600 | Short circuit in harness |
| Low voltage alarms | Low | £15–£40 | Battery or alternator |
| Erratic screed heating | High | £200–£700 | Short or bad sensor |
What Should I Check When the Screed Heater Elements Not Powering Up?
The Bomag BF 600 P-2 is equipped with diesel-fired heaters and electrical heating elements for the screed plate. If the heaters do not ignite or the electrical elements fail to glow, investigate both the control relay and the burner control unit. This system integrates with the electrical network, so a simple fuse can knock out the entire heating ability.
First, check the “SCREED HEATER” 30-amp fuse in the main panel. Replace if blown (cost about £5 per fuse). Then verify the heater relay under the right-side console: with the engine running and heater switch on, listen for a click. No click indicates a dead relay coil. Swap with an identical relay from the “SPARE” slot (common on Bomag machines). If the element still doesn’t power, use a non-contact infrared thermometer to temperature each heater zone. A zone reading ambient temp while others warm up signals a burned-out element. Replacement elements cost around £280–£450 each for the BF 600 P-2.
For a deeper dive into heater diagnostics, see the dedicated Bomag BF 600 P-2 Screed Heating System Troubleshooting Guide. That guide covers burner controller fault codes and fuel supply issues that often mimic electrical faults.
Why Does the Bomag BF 600 P-2 Screed Display Code “E-02”?
Code E-02 on the screed display indicates a CAN communication fault between the screed control module and the main machine ECU. This typically stems from a damaged CAN bus wire, a failed sensor node, or a loose connector in the screed junction box. Without proper communication, the screed defaults to a safe mode—locking all width and angle adjustments.
Inspect the CAN bus wires (usually yellow and green twisted pair) at the screed junction box, located behind the left extension frame. Look for cut or abraded insulation from repeated folding movements. Repair any damage using solder and heat shrink. Next, verify the sensor node for the mat thickness sensor—the most common node to fail. Unplug the sensor; if the code clears and changes to a sensor-specific code, replace the sensor (approx. £380).
Finally, ensure the CAN bus terminating resistor at the far end of the screed (right wing) is correctly seated. A loose resistor disrupts the entire bus. Torque to 2.5 Nm if it is a screw-in type. If the code persists after all checks, the screed control module may need replacement (cost near £2,500). But this is rare; 90% of instances resolve with wire repair or sensor replacement.
What Owners Say About the Bomag BF 600 P-2 Electrical System
Experienced paving contractors and fleet managers who use the Bomag BF 600 P-2 day in, day out report that the electrical system is generally robust but requires vigilant maintenance. One paving supervisor from a Midlands-based firm noted: “The CAN bus display is the first thing to show trouble if you skip the daily fuse and connector check. A blown fuse can stop the whole job.” Another operator mentioned, “We see width control issues every couple of years, but it’s always the same spot—the wire by the pivot arm. A good harness protector and you’re set.”
Many owners stress that the Bomag BF 600 P-2 vs Vögele Super 1800: In-Depth Comparison highlights the BF 600 P-2’s simpler electrical architecture, which makes DIY repairs more accessible. Some owners also share that investing in a spare wiring harness section for the left extension is wise, as downtime during paving season is costly. Overall, feedback underscores the machine’s electrical reliability when basic proactive care is applied.
Frequently Asked Questions
Q1: How often should I inspect the Bomag BF 600 P-2 electrical connections?
A1: At a minimum, inspect all connectors and fuses every 50 operating hours. For machines used in dusty or high-moisture environments, increase the interval to every 20 hours. Use dielectric grease on all exposed pins.
Q2: What is the typical lifespan of the Bomag BF 600 P-2 screed control module?
A2: With proper care, the module lasts 5,000 to 7,000 operating hours. However, repeated voltage spikes from weak batteries can shorten its life. Keep the battery and alternator in top shape to maximize module lifespan.
Q3: Can I use a non-OEM harness for the Bomag BF 600 P-2 screed?
A3: Yes, but only if it matches the gauge, pinout, and connector type. Non-OEM harnesses often use thinner wire (18 AWG instead of 16 AWG) which can overheat. For critical applications, OEM harness is recommended to avoid performance issues.
Q4: Why does my Bomag BF 600 P-2 screed heat only on one side?
A4: This usually indicates a failed heating element or a relay stuck open on that zone. Check the fuse for that side, then measure resistance across the element (should be 2–4 ohms). Open circuit means element replacement is needed.
Q5: How do I reset the Bomag BF 600 P-2 screed ECU after a fault?
A5: Turn the ignition off, disconnect the battery negative terminal for 60 seconds, then reconnect. This clears many transient fault codes. For persistent codes, a dealer diagnostic tool may be required to clear hard faults.
Q6: What is the cost to replace the entire screed wiring harness on a Bomag BF 600 P-2?
A6: The replacement harness costs approximately £1,800 to £2,400, plus about 4–6 hours of labour at £95 per hour. Total cost can reach £2,400–£2,900. Ensure you buy the latest revision to avoid compatibility issues.
