How To Fix Fault Code 427 On Cummins Generator (Error Solved!)


One of the not-so-common fault codes on Cummins power generators is fault code 427.

It can be part of a situation in which you are aware of what user actions led to it, do its appearance can be a bit alarming.

But also can be a signal of some very serious and costly problems with your generator.

No matter what the reason for the abrupt shutdown of your generator and the appearance of this fault code is, you would want to always have a reliable source of electricity.

So, how to fix fault code 427 on Cummins generator? To solve the fault code 427 on Cummins generator, just check and follow the steps below:

Step #1 Check the emergency stop button

Step #2 Reset the emergency stop button and generator

Step #3 Check the emergency stop button for faults

Step #4 Check CAN data link

Continue reading this post to find out what is fault code 427, what causes it, and how to fix it.

What is Fault Code 427 on Cummins Generator

Having the uninterrupted power supply when you need it the most is the reason why you have a Cummins backup generator.

So, having it shut down due to a fault code is a reason for concern.

Broadly speaking there are two possible reasons for the fault code 427 to show up, one is if the generator engine’s ECM has lost power or is broken, while the other is a faulty CAN link.

Both of these can be described as situations when the generator’s PowerCommand control unit is unable to communicate with the engine control module or ECM.

The engine control module is the brain of the engine, just like your car’s ECM, and in case that it is broken the engine, the heart of your generator is not able to tick either.

There are several possible causes of the fault code 427, while some you might be able to fix on your own, others are better left to professionals.

By attempting some of the repairs, you will void the warranty, if not causing greater damage to your generator.

Read also: How To Fix Fault Code 1246 On Cummins Generator

Reading the Fault Code on Cummins Generator

Cummins generators come equipped with PowerCommand controls, which provide a wealth of information about the status and operation of your generator, and not just the ability to turn it on and off.

When the shuts down due to a fault code, it will start displaying a message on the LCD screen while the shutdown LED indicator will also light up.

In case that you are having the fault code 427 on your hands, the LCD screen will read:

  • Fault Number 427: CAN DATA LINK DEGRADED

Depending on some conditions, you might also see the message:

  • Fault Number 1433: LOCAL EMERGENCY STOP

This means that the activation or faulty emergency stop button has led to disruption of power to the ECM.

Having one fault code jump at you can be alarming, but having two even more so to an average user of Cummins generators.

Especially if you have in mind that this condition will render the generator not operational until the cause is removed.

Read also: How To Fix Fault Code 1434 On Cummins Generator

Troubleshooting fault code 427

There are two reasons for the fault code 427 to sow up on your generator’s screen, either the ECM has lost power or is faulty, or the link between the PowerCommand control unit and ECM is broken.

Before you start troubleshooting the fault code 427, you should be aware that some potential issues you will be able to neither diagnose nor repair yourself.

They require some special tools, both software and hardware, which are not available to the general public and you can find them only in the officially certified Cummins repair shops.

Because of this, you are always better off consulting service than attempting repairs on your own.

But there are some things that you can do yourself.

The first is to check whether the part which always shuts power to ECM is active, the emergency stop button.

Step #1 Check the emergency stop button: By attempting to pull it out you can determine whether the emergency stop button was pressed or not.

In case that it was you should reset it and the generator, otherwise you should continue to step #3.

Step #2 Reset the emergency stop button and generator: After pulling out the emergency stop button you need to press the OFF/STOP button to reset it.

Next, you have to press the RESET button to reset the generator, and then either the Manual run or Auto button to select the desired mode of operation of your generator.

Step #3 Check the emergency stop button for faults: In case that the emergency stop button wasn’t activated, you should check whether it is faulty.

The quickest way is to check for the continuity on its two connectors with a voltmeter or to connect its terminals with a piece of wire and then attempt to reset it per step #2.

If there is no continuity, the button is broken and needs to be replaced.

While if the reset doesn’t remove the fault code 427, there is a problem somewhere else.

Step #4 Check CAN data link: The fault code 427 can happen because the CAN data link is interrupted either physically or electrically. With the service panel open, you will be able to access the harness very easy though it requires a bit of effort of reading the label of various connectors.

You will need to visually inspect whether the pin J11-20 connects properly to the pin J1939+, and pin J11-19 to J1939-.

If any of them is not properly secured, the CAN data link will be interrupted, and you need to properly secure them

You should also check for continuity across these pairs of pins if they are properly connected, as faulty wiring can interrupt the CAN link.

If one of the wires is faulty, the whole engine harness needs to be replaced, which is not something you will be able to do on your own, as the replacement part is not freely available.

If none of these steps have produced a solution, there are three more possible causes of the fault code that you will not be able to diagnose or fix by yourself, faulty keyswitch relay, ECM, or terminating resistors of the J11 connector.

Read also: How To Fix Fault Code 1433 On Cummins Generator

Causes of the Fault Code 427 You Can’t Fix

Keyswitch relay 

When the emergency stop button is pressed, it interrupts the power to the keyswitch, which then cuts off the CAN link communication.

But also the faulty keyswitch relay can lead to this situation.

Fiddling with this relay can cause damage to it, and attempting to replace it will lead to warranty-voiding, so it’s better left to a certified technician.

Faulty ECM 

For diagnosing the faulty ECM you would require proprietary software and hardware, namely the EControls’ 4G Diagnostic software and RS232 conversion cabling and connector.

Both of these are not available to the general public.

Terminating resistors 

While measuring the resistance between J11-19 and J11-20 pins is easy with a voltmeter, and should measure 60 ohms, and on two terminating resistors should measure 120 ohms, replacing them will void the warranty on your generator.

Prevent Fault Code 427 from Reoccurring

Causes of fault 427 are highly unpredictable and practically impossible to avoid.

A faulty emergency stop button, ECM, or engine harness very often happens due to sheer bad luck.

All of these three parts are intended to last the lifespan of the generator, but sometimes small and undetectable variations during the manufacturing can lead to them failing prematurely.

The good side of this is that chances are that you will experience this fault code only once, if ever.

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Mike Gilmour

Hi, I'm Mike, co-founder, and editor of RV and Playa. My passion is traveling (with my RV) and enjoying the day at the beach (Playa)! Well, I originally created this blog as a way to share what I've learned by experimenting with the RV lifestyle, and I want to help others develop in life through new skills and opportunities.

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