Maintenance: Service and Repair

Fig. 2 Emission Maintenance Reminder System. 1980-87 Dodge And Plymouth Electronic Type:

Instrument Cluster:

The system consists of two major elements, mileage counting contacts in the speedometer and an electronic digital switch module located in the upper center of the instrument cluster behind the fuel gauge.

Speedometer; 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 switch module once each mile.

Electronic digital switch module; This module consists of electronic components including several integrated circuits, which count and accumulate the pulses from the vehicle odometer cam contacts. After 52,224 pulses are stored, the output transistors activate and turn on the Emission Maintenance Reminder lamp (EMR). The circuit immediately returns to a zero mileage condition and starts to count and accumulate pulses until 52,224 are again stored and the process repeats.

The EMR module is accessed from the front of the instrument cluster. The lamp will remain lit until the switch module is reset by depressing the reset contact (located on the bottom of the electronic module) with a small flat-blade screw-driver. The nine volt alkaline battery must be removed before resetting lamp switch. The electric digital switch module is powered by the vehicle battery which should not be removed while the nine volt battery is removed. A long life nine volt alkaline battery is enclosed in the module case to provide power in the event the vehicle battery is disconnected. This battery must be replaced at 52,224 miles (84046 Km) maintenance point.

CAUTION: There is no test procedure for this system, any attempt to test it will result in damage to the system components.