Experiencing cruise control problems in your 2000 Ford F-550 7.3 diesel? You’re not alone. Many owners of these robust trucks encounter issues with their cruise control systems. Often, the first step in diagnosing these problems is to reach for a scan tool. If you’re facing a situation where your 2000 Ford 7.3 Scan Tool Not Communicating with the cruise control system, or you’re simply unsure where to start, this guide is for you. We’ll explore common issues, diagnostic steps, and potential fixes, drawing insights from real-world experiences to get your cruise control working again.
One owner of a 2000 Ford F-550 7.3 manual recently encountered a similar problem. Initially, their cruise control, speedometer, and odometer were all non-functional. After replacing the Vehicle Speed Sensor (VSS), the speedometer and odometer were restored, but the cruise control remained stubbornly inactive. Let’s delve into the troubleshooting process for this common issue.
Initial Troubleshooting Steps
The first actions taken by the truck owner were logical and mirrored typical diagnostic procedures:
- VSS Replacement: As mentioned, a new VSS fixed the speedometer and odometer issues. This is often a starting point when dealing with speed-related malfunctions.
- New Cruise Control Buttons: Suspecting worn-out buttons on the steering wheel, new buttons were installed. Unfortunately, this didn’t resolve the cruise control problem.
- Brake Pressure Switch Jumpering: To rule out a faulty brake pressure switch, the owner attempted to bypass it by jumpering the connection. This also yielded no positive results, and the cruise control remained inactive.
At this stage, the owner noted that no cruise control indicator lights illuminated on the dashboard when pressing the “ON” button. The horn, however, was working, suggesting that the clock spring might still be functional for basic steering wheel controls.
Scan Tool Insights and FORScan
The next logical step, and one highly recommended by experienced mechanics, is to use a scan tool to read diagnostic codes and live data. In the forum discussion, the suggestion was made to use a “good scanner that speaks Ford.” This is crucial because generic OBD-II scanners may not access Ford-specific systems and diagnostic parameters effectively.
FORScan (https://forscan.org/home.html) was recommended as a valuable tool for Ford and Mazda vehicles. FORScan is a software application, often used with an OBD2 adapter, that provides enhanced diagnostics and capabilities beyond generic OBD-II scanners. It can access manufacturer-specific codes, run tests, and display live data streams from various vehicle systems.
Using FORScan proved to be a turning point in this troubleshooting process. While it wasn’t a case of the “scan tool not communicating” at all, it was essential for deeper diagnosis. The owner connected FORScan and ran a self-test, which revealed crucial error codes.
Diagnostic Codes and Brake Switch Circuit Issue
The FORScan scan revealed several error codes, including codes related to the brake system. Specifically, the code C1446 (Brake Switch Circuit Failure Open or Shorted to Ground) stood out as potentially relevant to the cruise control issue.
Cruise control systems are designed to disengage immediately when the brakes are applied. Therefore, a fault in the brake switch circuit can certainly prevent the cruise control from engaging or functioning correctly.
Further investigation focused on the brake switch circuit. The owner had already tried jumpering the brake pressure switch on the master cylinder. However, the C1446 code indicated a more persistent issue within the brake switch circuit itself.
Exploring Potential Causes and Solutions
Based on the diagnostic code and the symptoms, several potential causes emerged:
- Brake Light Switch: This is the switch located at the brake pedal itself. A faulty brake light switch is a common cause of cruise control problems. The owner in the forum thread actually replaced this switch as part of a parts sale, further emphasizing its potential as a culprit.
- Brake Pressure Switch: While the owner had tried jumpering this switch, a faulty switch or wiring issue to it could still be the problem. It’s important to note that there are often two brake-related switches: the brake light switch at the pedal and the brake pressure switch on the master cylinder.
- Wiring Issues: The C1446 code specifically points to a circuit fault – “Open or Shorted to Ground.” This strongly suggests a wiring problem within the brake switch circuit. The owner later discovered broken wires at a connector, highlighting the importance of checking wiring harnesses for damage, corrosion, or breaks.
- LED Rear Lights: The truck in question had aftermarket LED rear lights due to its rollback configuration. LED lights draw significantly less current than traditional incandescent bulbs. In some vehicles, this difference in current draw can confuse the vehicle’s computer system, particularly the brake light circuit monitoring. This might lead to false brake switch circuit errors and cruise control deactivation. Adding resistors to the LED brake light circuit can sometimes resolve this issue by mimicking the current draw of regular bulbs.
- Clock Spring (Less Likely in This Case): While initially suspected due to the lack of dash light illumination, the working horn made a faulty clock spring less probable. The clock spring is a rotary electrical connector in the steering column that allows electrical signals to pass to the steering wheel controls (horn, cruise buttons, airbags) while the wheel turns. If the horn works, the clock spring is likely at least partially functional.
Cruise Control Light Behavior on 2000 Ford Trucks
An important point raised in the forum discussion is that the cruise control light on 2000-era Ford trucks typically does not illuminate until the cruise control is actually set and engaged. There is no “cruise ON” light that comes on simply when you press the “ON” button. This is different from some other vehicles where a cruise control indicator light confirms the system is active, even if not yet set to a specific speed.
This clarification is crucial for troubleshooting. The lack of a dash light when pressing “ON” on a 2000 Ford truck is normal and not necessarily indicative of a problem.
Step-by-Step Troubleshooting Guide
Based on the forum discussion and common issues, here’s a step-by-step guide to troubleshoot cruise control problems on a 2000 Ford 7.3:
- Scan for Diagnostic Codes: Use a Ford-specific scan tool like FORScan to read all diagnostic trouble codes (DTCs). Pay close attention to any codes related to the brake system, cruise control, or speed sensors.
- Address Brake Switch Circuit Codes: If you have a C1446 or similar brake switch circuit code, prioritize troubleshooting this issue first.
- Inspect Wiring: Carefully examine the wiring and connectors for the brake light switch at the pedal and the brake pressure switch on the master cylinder. Look for broken, corroded, or damaged wires. Repair any wiring issues found.
- Test/Replace Brake Light Switch: Use a multimeter to test the brake light switch for proper function. Replace if necessary.
- Test/Replace Brake Pressure Switch: Test the brake pressure switch. While the recall for fire risk is relevant, also check for electrical malfunction. Replace if needed.
- Check Cruise Control Buttons with Scan Tool (FORScan Live Data): FORScan can often display live data, including the status of cruise control button inputs. Use this feature to verify that the buttons are sending signals to the computer when pressed. If buttons are not registering, suspect faulty buttons or clock spring issues (though less likely if the horn works).
- Inspect Fuses: Check the fuses related to the cruise control system and brake lights. A blown fuse can disable the cruise control.
- Consider LED Light Resistors: If you have aftermarket LED rear lights, especially brake lights, try adding resistors to the brake light circuit to see if it resolves the issue.
- Check Clutch Switch (Manual Transmissions): For manual transmission trucks, a faulty clutch switch can prevent cruise control engagement. Test or bypass the clutch switch to rule it out.
- Verify Cruise Control System Presence: While less likely, especially if you have cruise control buttons, double-check that your F-550 model was actually equipped with cruise control from the factory. While most likely it is, it’s a simple check to eliminate any doubt.
Conclusion
Troubleshooting cruise control problems on a 2000 Ford 7.3 often requires a systematic approach and the right tools. While a 2000 Ford 7.3 scan tool not communicating directly with the cruise control module might be a concern in some cases, in many scenarios, the scan tool (especially Ford-specific tools like FORScan) is essential for identifying the root cause. Error codes, particularly those related to the brake switch circuit, can provide valuable clues. By methodically checking wiring, switches, and utilizing diagnostic tools, you can effectively diagnose and resolve most 2000 Ford 7.3 cruise control issues and get back to enjoying comfortable highway driving.
