O2 Sensor Heater Relay - Fault C1003 Set

88amcjeep05

Models

1988 Cherokee, Wagoneer And Comanche With 4.0L Engine


Subject

MS 1700 Diagnostic Tester Fault C1003
- O2 Heater Line High


Index

ELECTRICAL


Date August 1, 1988


No.

08-54-88


P-3083 (C08-59)
SYMPTOM/CONDITION

The MS 1700 Diagnostic Tester may display a "Fault C1003 - O2 Heater Line High" while performing a "Vehicle Test" on some early built 1988 Cherokee, Wagoneer and Comanche vehicles with a 4.0L engine. This Fault could be caused by an oxygen sensor (O2) heater relay connector which is improperly wired for use with the 1988 MS 1700 Diagnostic Tester Cartridge (PN 8980-003- 021).

DIAGNOSIS

If a "Fault C1003 - O2 Heater Line High" occurs, verify that the vehicle being tested is a 1988 Cherokee, Wagoneer or Comanche with a 4.0L engine and the MS 1700 Diagnostic Tester Cartridge is PN 8980-003-021. Turn the ignition switch to the "ON" position. Check for voltage at the diagnostic connector pin D2-9. If the initial voltage is greater than 9 volts and drops to 0 volts after 3-5 seconds, the O2 heater relay connector is properly wired and the technician should refer to the C1003 fault tree in the MS 1700 Diagnostic Tester Manual for diagnostic procedures. If the voltage is greater than 9 volts and does not drop to 0 volts after 3-5 seconds, the O2 heater relay connector wiring is not compatible with the 1988 Diagnostic Tester Cartridge and the technician should perform the following repair procedures.

REPAIR PROCEDURES

1. Turn the ignition switch to the OFF position.

2. Disconnect the battery negative cable from the battery and remove the relay cover.

3. Remove the four relay connectors from the bracket on the right inner fender panel by squeezing the locking tabs on the fender side of the bracket.

FIGURE 1:

4. Separate the O2 sensor heater relay (A) and connector from the rest of the relays. Figure 1
NOTE: THE O2 SENSOR HEATER RELAY MAY BE IDENTIFIED AS THE ONLY RELAY WITH A GRAY WIRE.
5. Remove the O2 relay from its connector.

6. Pry the white plastic retaining clip (B) from the relay connector. Figure 1

FIGURE 2:

7. Insert a paper clip into cavities 1 and 5 from the relay side, to release the locking tab of the terminals. Switch the wires in the cavity holes. The orange wire (fuel pump feed) goes into cavity 1 and the yellow (ignition) wire goes into cavity 5. Figure 2
8. Install the white plastic retaining clip.

9. Install the O2 relay into its connector.

10. Attach the O2 relay assembly to the other three relay assemblies and install them to the fender bracket.

11. Connect the battery negative cable.

12. Verify the repair with the MS 1700 Diagnostic Tester before installing the relay cover.


POLICY: Reimbursable within the provisions of the warranty.


SRT/TIC INFORMATION:

OPERATION
OPERATION DESCRIPTION NUMBER TIME TIC FAILURE CODE

CO. WIRES, RELAY-CHANGE 0103 0.3 1-838

CO. MS 1700 TEST 0103 0.3

08-65-18-90 0.6 51