Dakota 2WD V6-239 3.9L (1987)
Maintenance Required Lamp/Indicator: Service and Repair
Emissions Maintenance Reminder System
Emissions Maintenance Reminder
Electronic System
This maintenance reminder system is a mileage counting system. An instrument panel lamp (CHECK EGR) will come on after mileage accumulations
of 52,500, 82,500, and 105,000 miles.
The purpose of this system is a reminder that the emission maintenance must be performed as soon as possible. It is not intended to indicate a warning,
or that a state of emergency exists which must be corrected to insure safe vehicle operation.
The system consists of two major elements; mileage counting contacts in the odometer, and a digital electronic module. A permanent magnet is
connected to the tenth wheel of the odometer which rotates once each mile. The magnet closes a set of normally open contacts, sending an electrical
pulse to the electronic module once each mile. The module consists of electronic components, including several integrated circuits which count and
accumulate the pulses from the vehicle odometer switch contacts. After 52,500 pulses are stored, the output transistor activates and turns on the
emission maintenance reminder lamp. The module continues counting and accumulating pulses even while the lamp is illuminated, until the next trip
point is reached.
The lamp will remain lit until the module is reset by inserting a small screwdriver blade or rod into the hole in the case of the module, closing a switch
and turning off the lamp. A nine-volt alkaline battery, which is enclosed in the module case to provide power in case the vehicle battery is
disconnected, must be removed in order to reset the module switch. This battery should be replaced at the 52,500 mile service point. The nine-volt
alkaline battery should never be removed while the wiring connector is disconnected from the module, and the wiring harness should not be
disconnected when the nine-volt battery is removed to reset the module switch.
CAUTION: There is no test procedure for this system, any attempt to test It will result In damage to the module.
After necessary emission maintenance has been performed, reset module as follows:
1. Slide module from bracket.
2. Insert a small screwdriver into small hole on module case and close switch.
3. Remove module battery cover and install a replacement 9 volt battery.
4. Position module on mounting bracket.
