Oil Monitoring Light

Automobile owners benefit from regularly scheduled, routine maintenance in several ways. For one thing, properly maintained fluids can extend the life of the vehicle. Additionally, vehicles that have been inspected on a regular basis are safer to operate. And now that the Lifetime Powertrain Limited Warranty has been introduced, it is more important than ever that the maintenance performed on a vehicle satisfies warranty requirements.

As vehicle maintenance improves and warranty repairs decrease, routine maintenance becomes an increasingly important part of the business in your shop. And as with any other area of automotive service, it is essential to keep pace with changes in this area.

In order to take some of the guesswork out of when a particular service procedure should be performed, Chrysler LLC has introduced Maintenance Indicators over the last couple of years on many models. The indicator that has drawn the most attention is the one that informs the driver when it’s time to change the engine oil. While there are many items on the regular maintenance list, changing the oil is probably the one task that most vehicle owners perform (or have done). Now it is even easier for them to remember when to do it.

Wondering how this maintenance indicator works? Let’s see how these systems work, paying specific attention to the oil change monitor.

SCHEDULED MAINTENANCE

Schedules A and B (normal duty and severe duty respectively) have been a part of the required and recommended maintenance on Chrysler LLC vehicles for many years. The major drawback to using these schedules is that vehicle owners don’t always know which schedule applies to their driving habits. They end up making a best guesstimate of the correct maintenance for their vehicle.

For the vast majority of driving conditions, it is difficult for the driver to know when an oil change is required. With the introduction of the oil change indicator system, the guesswork is taken out of the equation. The driver is automatically notified via the cluster or Electronic Vehicle Information Center (EVIC) that an oil change is required (Figure 1).

BASIC OPERATION

The brains behind the oil change indicator system is the Powertrain Control Module (PCM). It processes a variety of inputs (hardwired and bussed inputs) to decide the oil change interval. The PCM then broadcasts this interval decision, via the vehicle bus communications system, to the driver through a message on the odometer or EVIC display in the instrument cluster (Figure 2).

There are six inputs used by the PCM. The factors which indicate severe use (and a shorter oil change interval) for each of these inputs are listed below:

• Ambient temperature – extended periods of low temperature operation
• Average vehicle speed – stop and go driving
• Engine run time – prolonged idling
• Trip length and coolant temperatures – short trips
• Engine speed and load – trailer tow usage
• Flex-fuel percentage – ethanol percentage of more than 60%

Based on this information, at a fixed number of miles since the last reset of the system, the PCM calculates the combined effects of these variables to determine if a severe usage pattern exists. If severe usage is determined, the oil change message is activated at 2,500 miles; otherwise, the message is not displayed until additional mileage has accumulated.

It should be noted that this system cannot keep track of dusty conditions or time elapsed since the last oil change (calendar time). In fact, it is possible for the maximum allowable maintenance time interval to elapse without an oil change reminder being displayed. In such a case, it is the responsibility of the owner to change the oil based on the recommended interval.

MESSAGE DISPLAY

The oil change indicator message is displayed in the odometer window for 10 to 12 seconds when the vehicle is started (Figure 1). The message is also accompanied by a chime. The message can be hidden by pressing the trip button, but it will reappear the next time the vehicle is started.

RESETTING THE OIL INDICATOR DISPLAY

After the oil has been changed, the system needs to be reset to stop the display of the oil change message.

Resetting the system is done in the following manner:

• Turn the ignition key to the ON position
• Slowly depress the accelerator pedal to the floor and release it three times within 10 seconds (Figure 3)
• Turn the key to the OFF position
• Repeat this procedure if the indicator does not reset

Remember, the system must be reset after every oil change regardless if the Change Oil Required message is displayed. If the system is not reset, a premature message for the next oil change will be displayed.

For example, let’s say you have a vehicle were the engine oil is changed at 2,500 miles no matter how it’s driven. We’ll assume that the system determines that the oil should be changed at 3,500 miles. If the oil is changed as planned and the system is not reset, the oil change message will be displayed 1,000 miles after the oil change.

IMPORTANCE OF THE MESSAGE

With the use of this maintenance indicator system on many late model Chrysler LLC vehicles, it is important to be mindful that such a system is installed on these vehicles. It is important to know where the message is displayed and what it means. This process should begin with new vehicle delivery and continue when the vehicle is brought in for service.

Furthermore, it is important to know that the onboard computer in their car is making the decision when the oil should be changed. The decision is based on how the vehicle is driven; therefore, the mileage between oil changes can vary.

In addition to the oil change, the related items listed in the service information should also be performed at this time. Such items include changing the oil filter and checking the transmission fluid level. All other items will follow a single maintenance schedule with the same calendar/mileage intervals regardless of the oil change interval. These include checking tire pressure and wear.

With its sophisticated calculations, the new maintenance indicator system helps take the guesswork out of selecting the correct maintenance schedule to follow. In addition, the messages are a good way for you to position yourself as your customer’s first choice for maintenance and service.