Chart B1 - Inoperative Odometer
An incorrect odometer reading can be caused by one of several different problems relating to power and ground circuits. Caused not only in IPC, but those of other components within the computer network, the computer wake-up signals, the vacuum fluorescent power supply, the odometer mileage memory chip (EEPROM) contained in BCM, or by data line between computer components.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- In order to begin to isolate cause of an IPC odometer problem, if no codes are set in diagnostic memory, observe state of odometer reading with headlamp switch and twilight sentinel switch in "OFF" position. This is important as these signals can wake-up the BCM and cause a misdiagnosis of a malfunctioning primary circuit.
- When odometer reads all zeros, actuating interior courtesy lamps switch will help to isolate exact cause of problem. This symptom is caused by a failure in computer system other than the IPC. Further isolation of this fault is analyzed in CHARTS B2, B3 and B4.
- When odometer is blank or reads all 8's, actuating headlamp will help to isolate cause of problem. If odometer reads all zeros, cause of problem is due to a faulty ignition-3 feed to BCM (open or shorted to ground) or BCM itself. If odometer is blank or reads all 8's, cause is due to one of several other problems within computer network.
- Cycling the high beam or headlamp dimmer switch will help to further isolate cause of problem. If high beams cycle, problem is related to IPC itself, IPC ground circuit, vacuum fluorescent power supply circuit or components related to these circuits. This analysis is contained in CHART B5.
- If high beams did not cycle when dimmer switch was actuated, turning on courtesy lamps switch will help to further isolate system problem. If courtesy lights turn on, problem is related to IPC itself, the CPS to IPC logic circuits ground, the 12-volt power circuits from CPS to IPC or CPS itself. Further problem isolation is contained in CHART B6.
- If courtesy lamps did not turn on when switch was actuated, several other causes for problem can be isolated by following CHARTS B7 and B8, depending on whether the "LIGHT ON" chime sounds when test is run.