HRR688 Ignition Module

This is the finest most Accurate and Dependable Intel Micro-Processor Engine Control Module in this industry.

EVERY HRR688 Ignition Box is test run on a distributor machine before it leaves the factory and batch tested on a vehicle before they leave our shop. 

If you should encounter a crank no start condition then follow these steps to trouble shoot the problem.

You must have a good ground from the engine to the firewall and the box must be grounded properly to the firewall


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Do Not try and plug the system in with the ignition key in the RUN position, if you miss the pin and feed 12V to any other pin you will destroy the box and this error is NOT covered under our warranty.  Turn the key to OFF, plug in the box, start engine.

You must jumper or bypass the Ballast Resistor, although the engine will probably start with a ballast resistor this will deliver a low voltage signal to the ECU and prolonged running will cause failure, this is easy for us to assess and is not warranty.  Voltage to the ECU should be the same or just below battery voltage with the key in the run position 11V-13V usually.  When engine is running it should read 13-14.4V


Make sure the factory plug is clean and the female connectors are not stretched out so as not to make a solid connection.  As will all computer style components a good connection is critical to their operation. If your plug shows it's age we have new wiring harness' available.

We also recommend you use a small amount of dielectric grease on each pin to help prevent any corrosion buildup in the plug.  The Box itself is Water resistant and works in nearly any environment you can subject your vehicle to.  This box does not at this time have a USCG certification for Marine applications, we plan to submit it for USCG certification possibly in 2020.  We can not recommend using it in a marine application until the US Coast Guard approves it.

REV Limiter

0 on the dial is 5200 RPM, each click is 200 RPM to 9 which is 7000 RPM


Turn the key to the run position, the Box will run a self diagnostic test in under a 1/2 second the LED Status light will come on solid RED.

If it doesn't light up you probably have no power to the box or an inadequate ground.

Crank the engine, if the LED flashes its reading each voltage impulse from the pick-up coil and is firing as normal.

No flash? your not getting a signal from the distributor, Check for broken rotor, wiring to coil, voltage to coil, reluctor gap, 2 prong plug.

Solid and Flash? Engine still does not fire.....

Check to be sure it has fuel. Is the timing set correctly?

You can also connect your Timing Light to the Coil Wire and see if it flashes, if the timing light flashes then you have ignition to the cap... did you forget to install the rotor?  You can check each cylinder for fire by connecting your timing light to each wire and cranking the engine, it will flash.

Crank-Flashing-still no start?  Disconnect the tach wire from the -side of the coil.

The HRR688 is built on a Level 5 Electronics platform which is like a new style Laptop Computer or cell phone which includes 2 Intel Micro-Processors, there is nothing you can do to fix it or test the Processors, Do not take it to an Auto Parts store to be tested they cannot test this computer no matter what they tell you, call us for more help and if necessary a Return Authorization

Basic trouble shooting procedures must be performed before a Return Authorization will be given, Mopar Ignition is simple and with our system it is further simplified, test for power to the center pin on the plug, be sure the plug is in good condition, check voltage at the + side of the Coil.  Check for continuity between the ECU plug and the distributor plug.  The most common issue we see is old worn out ECU plugs... CHECK the plug.

If it has 6V-18V on the main power supply, it's grounded properly to the firewall and the engine is also grounded to the firewall that's all you can test on the ECU.

Call us and we'll give you our return policy and a return authorization number.  As of 10.30.17 we now have over 5000 units in service worldwide and have had only 3 warranty claims, all 3 were incorrect coil, bad connections or ground related failures.  We know they work when they leave our shop as every batch is random tested on a vehicle with the REV Limiter set at 5200 RPM and our product will always be tested as part of our Quality Control Program.

FBO Ignition Systems is always working on new and innovative products to make your Mopar run stronger and more reliable.  Here's our latest entry, our J685S with 6 position mechanical advance limiter disc. Simple installation of this disc will allow you to limit your mechanical timing to 0-10-12-14-16 or 18* with NO permanent modifications to your distributor, no welding, no grinding, no frustration.

See how easy it is to install

Installation of J685S Limiter plate

See more here:

Mopar Limiter Plates

GOT MSD? Check this tuning tips Article



Just a few notes regarding Ignition:

1. A good ignition system will not add HP, if may allow you to make more HP by firing each cylinder correctly and efficiently but claims of massive HP gains against well known and proven Performance Ignition Systems is just plain False and can usually be found on the bottom of a cattle trailer.

2. These are Inductive Ignition Systems and it's well known by Qualified Electronic Engineers that some can work reasonably well to 7,000 RPM on a V8 engine after that you need to run a CD Ignition like a Daytona-Sensors Made in America CD Ignition Box.

3. 80,000V system?... not likely needed on a naturally aspirated engine with a carburetor on top.  Any system will only develop enough voltage to jump the spark from the electrode of the spark plug to the ground strap.  There's many variables which determine how much voltage it takes for that spark to make the leap but If everything is set correctly the average naturally aspirated street strip car will only require only 26KV to 30KV to fire the plug.  You can force it to build more Voltage by over gapping the plugs, using high resistance plug wires, poorly designed cap and rotor but this usually just causes the coil to fail prematurely and won't make any more HP.  Don't be fooled by fancy advertising and crazy claims... it's just not true.

4.  "Ignition First- then Carburetion"

5. Any engine that will make 10" or more of manifold vacuum with 30* initial timing will greatly benefit from a properly set up vacuum can and it will NOT affect the car on track or under any load condition.  If the car is driven on the street the vacuum canister can improve fuel economy by 10-40%.

6. 90% of rich Idle conditions are caused by incorrect timing events and have nothing to do with the carburetor. Go back to #4.

7. Hot Rods, Muscle Cars, Classic Cars or nearly any performance application the Vacuum Can is connected to the CONSTANT Manifold Vacuum source.  Doesn't matter what you read on the internet if you don't have any computer controls, Catalytic Converters or other emissions equipment it goes to CONSTANT.  End of discussion.

8. If your car makes that magic 10" or more of vacuum then DO NOT try and run a Non-Vacuum race only Billet Distributor, they are for engines with a camshaft duration at 50 of 250* or more.


End of speech.



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This page last updated 11.24.17