For owners of a classic 1997 Ford F-250 diesel truck struggling to get their Prestige Remote Start Key Fob system working reliably, you’re not alone. Many enthusiasts encounter challenges, particularly with tach signal and glow plug cycles affecting cold starts. After extensive trial and error, this guide shares a successful approach to overcoming these common hurdles and achieving consistent remote start functionality with your Prestige system.
Understanding the Remote Start Problem: Tach Signal vs. Voltage Mode
Remote starters rely on accurate engine data to function correctly. Two primary methods exist for signal detection: voltage sensing and tachometer (tach) signal. While voltage mode might seem simpler, it often proves unreliable for diesel engines, especially during cold starts. Diesel engines, like the 7.3L Power Stroke in the 1997 F-250, draw significant power for glow plugs during initial startup, especially in cold weather. This heavy draw can confuse voltage-sensing remote starters, leading them to misinterpret the engine’s status and fail to start or even prematurely shut down after a brief start.
For reliable operation, especially in colder climates and with diesel engines, utilizing a tach signal is crucial. The tach signal provides direct feedback on engine RPM, offering a much more accurate representation of the engine’s running state to the remote start system.
Debunking the White/Pink Tach Wire Myth
A common piece of advice for finding a tach signal wire in older Ford trucks points to a white/pink wire located near the brake pedal at the PCM firewall connector. While this wire might carry some signal, experience shows it’s often insufficient for Prestige remote starters and likely other brands as well. Prestige specifically states their systems require a 5-8v AC signal for tach input. The white/pink wire, unfortunately, typically does not provide this necessary signal strength or type, leading to unreliable remote start performance.
Exploring the “Dark Green Wire” Alternative
Prestige tech support suggested an alternative: a “dark green wire” within the wire loom running over the driver’s side valve cover, often identified by red tape around the loom. The suggestion was that this wire might be related to the cam position sensor and potentially carry a 5v signal. However, without a definitive wiring diagram to confirm the exact function and signal characteristics of this “dark green wire” (and the ambiguity of “dark green” vs. “light green”), tapping into it presents a risk. Uncertainty around this wire led to exploring a more controlled and ultimately successful solution.
The Directed Electronics 454T Tach Generator: A Potential Solution
Given the challenges with direct wire tach signals, a tach signal generator like the Directed Electronics 454T becomes a valuable tool. These devices are designed to create a clean, reliable AC tach signal suitable for remote starters. The 454T installation is generally straightforward: power (red wire to battery), ground (black wire to chassis), and connections for signal output (black and grey wires). Crucially, it includes multiple output wires (green, orange, white, yellow) to generate varying AC signal strengths. By testing these output wires with a voltmeter, you can identify the pair that produces the desired ~5v AC signal for your Prestige remote start system. In this case, the green and orange wires proved to be the correct output.
Initial Setup and Tach Learning Frustrations
Following the 454T instructions, the initial setup involves connecting the black/grey output wire to the remote starter’s tach signal input. However, even after correctly wiring the 454T and performing the “tach learning” procedure for the Prestige system, reliable remote starts remained elusive. The tach learning process itself can be finicky, often requiring precise timing.
Prestige Tach Learning Procedure (Key Steps):
- Turn the ignition key to the “ON” position (just before the starter engages, where glow plugs activate).
- Immediately upon reaching “ON,” locate the Prestige valet button/antenna and press it three times. A horn honk should confirm successful recognition of the button presses. (If no horn, retry with more deliberate and correctly timed presses).
- Immediately turn the key to the “OFF” position.
- Immediately press and hold the valet button.
- While holding the valet button, start the truck with the key as you normally would.
- Observe the parking lights. They should begin flashing, indicating the system is “learning the tach signal.”
- Continue holding the valet button for at least 10 parking light flashes (you might hear the parking light relay clicking).
- Release the valet button. Tach learning is now complete.
Despite successful tach learning and initial remote starts working intermittently (especially when the engine was warm), cold starts remained problematic. The system would either just bump the starter or start and then immediately shut down, indicating an unstable or insufficient tach signal.
The Breakthrough: Direct 454T Output Connection
The key realization came from re-examining the voltage levels. While the 454T green/orange wires produced the desired ~5v AC signal, the black/grey output wire, as per the 454T instructions, only delivered a significantly lower 0.5v signal. This discrepancy explained the unreliable performance. The Prestige remote start system, expecting a ~5v AC tach signal, was not receiving a strong enough signal through the standard 454T output connection.
The solution was to bypass the 454T’s intended output wire and directly connect the Prestige remote start’s tach signal input wire to the green and orange wires of the 454T. This direct connection provided the Prestige unit with the stronger, required ~5v AC signal.
After rewiring the tach signal and repeating the tach learning procedure, followed by performing at least four manual key starts (to allow the remote start system to “average” the engine’s starting characteristics), the remote start system showed a dramatic improvement. While the very first remote start attempt might have bumped the starter momentarily, subsequent attempts, including cold starts after the truck sat overnight, proved successful and reliable.
Steps to Reliable Prestige Remote Start on a 1997 F-250 Diesel:
- Bypass Voltage Mode: Do not rely on voltage sensing for tach signal.
- Avoid White/Pink Wire: The white/pink PCM wire is unlikely to provide a suitable tach signal for Prestige systems.
- Install DEI 454T Tach Generator: This device is crucial for creating a reliable tach signal.
- Identify 5v AC Output on 454T: Using a voltmeter, determine which pair of output wires (green, orange, white, yellow) on the 454T produces approximately 5v AC signal when the engine is running. (Green and Orange were successful in this case).
- Directly Connect Tach Signal: Connect the Prestige remote start’s tach signal input wire directly to the 5v AC output wires identified in step 4 (e.g., green and orange wires of the 454T). Do not use the black/grey output wire as instructed by 454T for Prestige systems.
- Perform Prestige Tach Learning: Follow the Prestige tach learning procedure precisely, paying close attention to the valet button timing and horn confirmation.
- Manual Key Starts: After tach learning, perform at least 4 manual key starts to allow the remote start system to learn and average the engine’s starting characteristics.
- Test Remote Start: Attempt a remote start, including a cold start after the truck has been sitting for an extended period.
By implementing this direct connection approach and focusing on a strong, reliable tach signal, you can significantly improve the performance of your Prestige remote start key fob system on your 1997 Ford F-250 diesel, finally enjoying the convenience of remote start even on cold mornings.
