Chart B-1 Odometer Problem

Chart B-1:

Schematic:

DESCRIPTION:

An incorrect odometer reading can be caused by one of several different problems relating to power and ground circuits, (not only the IPC, but those of other components within the computer network,) computer system wake-up signals, the vacuum fluorescent power supply, the odometer mileage memory chip (EE PROM) contained in the BCM, or the data line between computer components.

1. In order to begin to isolate the cause of an IPC odometer problem, if no codes are set in the diagnostic memory, observe the state of the odometer reading with the headlamp switch and twilight sentinel switch in the "OFF" position. This is important because these signals can wake-up the BCM and otherwise cause a misdiagnosis of a malfunctioning primary circuit.

2. When the odometer reads all zeroes, actuating the interior courtesy lamps switch will help to isolate the exact cause of the problem. This symptom is caused by a failure in the computer system other than the IPC. Further isolation of this fault is analyzed in CHARTS B-2, B-3 and B-4.

3. When the odometer is blank or reads all eights, actuating the headlamp will help to isolate the cause of the problem. If the odometer reads all zeroes, the cause of the problem is due to a faulty ignition-3 feed to the BCM (open or shorted to ground) or the BCM itself. If the odometer is blank or reads all eights, the cause is due to one of several other problems within the computer network. If the display is normal, the cause is due to a open or short to ground in CKT 588 (16 volt VF input to radio) or CKT 8 (incandescent bulb output from IPC).

4. Cycling the high beam, or headlamp dimmer switch, will help to further isolate the cause of the problem. If the high beams cycle, the problem is related to the IPC itself, the IPC ground circuit or the vacuum fluorescent power supply circuit or the components related to these circuits. This analysis is contained in CHART B-5.

5. If the high beams did not cycle when the dimmer switch was actuated, turning on the courtesy lamps switch will help to further isolate the system problem. If the courtesy lights turn on, the problem is related to the IPC itself, the CPS to IPC logic circuits ground, the 12 volt power circuits from the CPS to the IPC or the CPS itself. Further problem isolation is contained in CHART B-6.

6. If the courtesy lamps did not turn on when the switch was actuated, several other causes for the problem can be isolated by following CHARTS B-7 and B-8, depending on what the voltage is on pin C5 of the CPS connector.