FJ62 Instrument Voltage Regulator
Donation protected
As the FJ60 and FJ62 series of Toyota Land Cruisers age, so do their electrical systems. A common frustration for owners is the occasional spiking of both the fuel and engine temperature gauges (sometimes clear to the upper limit of needle movement!). This is because the fuel and temp gauges aren't designed to be powered by the full system voltage.
Enclosed in the fuel gauge is a combination of breaker points and a DC inductor. The points are controlled by a very fine wire wrapped around an armature that heats up as current passes through it and causes the arm to bend, opening the circuit by separating the breaker points. The duty cycle of this open/close action is what "regulates" the voltage applied to the fuel and temp gauges. The inductor is in place to prevent sudden, dramatic shifts in the current passing through the circuit, which would otherwise cause the needles to fluctuate with the open/close action of the breaker points. Similar to the way a steering damper will help prevent shaking and vibration in a steering wheel when on rough terrain.
As these systems age, the points start to develop corrosion from years of minor electrical arcing and eventually begin to stick together. This is what causes the sudden spikes seen in the fuel and temp gauges. As they stay connected, the armature for the points gets more and more heated from the current passing through the wire and quickly overcomes the sticking, but not before giving an unfamiliar driver a scare that his engine is overheating.
The mechanical regulator can be replaced, but requires replacing the entire fuel gauge for $75-$80 directly from Toyota, and even then you'll still have an old style voltage regulation system that is susceptible to the same faults as the original. Removing the mechanical regulator from the fuel gauge's power lead and installing a solid state voltage regulator will ensure a lifetime of smooth, reliable operation of the fuel and temp gauges.
What you see in the title picture is my FJ62's quad gauge using my first properly functioning prototype. The design has already undergone drastic changes and likely still will before reaching a production stage. During initial prototyping, the solid state regulator has also proven slightly more sensitive than the mechanical regulator, in a good way. I could watch my engine temperature increase until the thermostat opened, and then quickly decrease to its normal operating range as the thermostat opened. This is much more easily noticeable than when I relied on the mechanical regulator.
I'm using Gofundme to fund small components for prototyping and manufacture (capacitors, resistors, circuit boards, diodes, etc.), supplies (solder, flux, SMT soldering gear for the production models, anti-static bags, shipping envelopes, etc.) and the first large scale production run of PCBs, which I will install necessary components on and test in my own shop to ensure each regulator operates properly before being mailed out. Pricing of the final product will be set at $30 each, in an effort to keep the product affordable as a more realistic alternative to replacing an otherwise functional fuel gauge, or resorting to frequently disassembling your gauge cluster to clean the breaker points. If enough units are sold after an initial production run at $30 each, that will allow me to do future production runs and fund the needed supplies.
Enclosed in the fuel gauge is a combination of breaker points and a DC inductor. The points are controlled by a very fine wire wrapped around an armature that heats up as current passes through it and causes the arm to bend, opening the circuit by separating the breaker points. The duty cycle of this open/close action is what "regulates" the voltage applied to the fuel and temp gauges. The inductor is in place to prevent sudden, dramatic shifts in the current passing through the circuit, which would otherwise cause the needles to fluctuate with the open/close action of the breaker points. Similar to the way a steering damper will help prevent shaking and vibration in a steering wheel when on rough terrain.
As these systems age, the points start to develop corrosion from years of minor electrical arcing and eventually begin to stick together. This is what causes the sudden spikes seen in the fuel and temp gauges. As they stay connected, the armature for the points gets more and more heated from the current passing through the wire and quickly overcomes the sticking, but not before giving an unfamiliar driver a scare that his engine is overheating.
The mechanical regulator can be replaced, but requires replacing the entire fuel gauge for $75-$80 directly from Toyota, and even then you'll still have an old style voltage regulation system that is susceptible to the same faults as the original. Removing the mechanical regulator from the fuel gauge's power lead and installing a solid state voltage regulator will ensure a lifetime of smooth, reliable operation of the fuel and temp gauges.
What you see in the title picture is my FJ62's quad gauge using my first properly functioning prototype. The design has already undergone drastic changes and likely still will before reaching a production stage. During initial prototyping, the solid state regulator has also proven slightly more sensitive than the mechanical regulator, in a good way. I could watch my engine temperature increase until the thermostat opened, and then quickly decrease to its normal operating range as the thermostat opened. This is much more easily noticeable than when I relied on the mechanical regulator.
I'm using Gofundme to fund small components for prototyping and manufacture (capacitors, resistors, circuit boards, diodes, etc.), supplies (solder, flux, SMT soldering gear for the production models, anti-static bags, shipping envelopes, etc.) and the first large scale production run of PCBs, which I will install necessary components on and test in my own shop to ensure each regulator operates properly before being mailed out. Pricing of the final product will be set at $30 each, in an effort to keep the product affordable as a more realistic alternative to replacing an otherwise functional fuel gauge, or resorting to frequently disassembling your gauge cluster to clean the breaker points. If enough units are sold after an initial production run at $30 each, that will allow me to do future production runs and fund the needed supplies.
Organizer
Daniel Moeller
Organizer
Spokane, WA
