Overhead Console - Temperature Inaccurate
NO: 08-22-96GROUP: Electrical
DATE: Jul. 26, 1996
SUBJECT:
Over Head Console
Temperature Accuracy
MODELS:
1996 (ZJ) Grand Cherokee
1996 (ZG) Grand Cherokee (export)
SYMPTOM/CONDITION:
The outside temperature reading in the overhead console mini computer may not be accurate when the heater A/C blower fan is operating. This is due to a ground feedback which can occur when the blower fan is operating at higher speeds.
DIAGNOSIS:
Operate the vehicle with the heater A/C system off and observe the temperature reading in the overhead console. Turn the heater A/C system on and turn the blower to high speed while observing the temperature reading. If the temperature reading changes when the blower is operated, perform the Repair Procedure.
PARTS REQUIRED:
1 4778570 Heat Shrink Tubing (2 pieces)
AR NPN Light green 20 gauge wire (18 inches)
REPAIR PROCEDURE:
This bulletin involves relocating the temperature sensor ground circuit to isolate it from the blower fan ground.
1. Record radio preset stations and disconnect and isolate the battery negative cable.
2. Remove both switch pod bezels.
3. Remove the cowl side trim panels (kick panels).
4. Remove the two bolts that secure the lower instrument panel reinforcement to the instrument panel bracket.
5. Remove the steering column shrouds.
6. Remove the nuts securing the steering column toe plate at the base of the steering column.
7. Remove the ash tray and remove the bolt that secures the instrument panel to the heater A/c housing.
8. Pull back the carpet in the center of the instrument panel and remove the two bolts that secure the instrument panel to center floor bracket.
9. Remove the bolt securing the instrument panel to the brake pedal support.
10. Remove the two bolts at the corners of the instrument panel near the windshield fence.
11. Remove the cowl trim panel and remove four nuts located under the trim panel.
12. With the aid of a helper, lift and rotate the instrument panel down to gain access to the back side of the panel. Use caution not to stress any electrical or vacuum connections. Make any disconnection required to avoid any stress being applied to the harnesses.
13. Locate the black 20 way C235 connector in the main instrument panel harness connector bracket at the lower left corner of the IP. Cut the 20 gauge, light green with white tracer wire, located in cavity 11, approximately 3 inches from the insulator. Tape the harness end of the wire to the harness making sure to cover any exposed copper wire.
14. Locate the black Body Control Module (BCM) connector C240. Cut the light green with white tracer wire, located in cavity 2, approximately 3 inches from the connector. Tape the harness end of the wire making sure to cover any exposed copper wire.
15. Slide a piece of heat shrink tubing, P/N 4778570, over remaining piece of wire at the body controller connector.
16. Using Rosen core solder, solder one end of an 18 inch piece of light green 20 gauge wire to the wire at the BCM connector. Slide the heat shrink tubing over the solder connection and apply heat with a heat gun to shrink the tubing.
17. Route the wire over the main harness to the C235 connector and tape it to the harness approximately every six inches.
18. Slide a piece of heat shrink tubing over the wire at the C235 connector.
19. Cut the new wire to the appropriate length and solder it to the wire at the C235 connector using Rosen Core solder. Slide the heat shrink tubing over the solder connection and apply heat to the tubing with a heat gun to shrink the tubing.
20. Install the instrument panel, reversing the disassembly procedure described above.
21. Connect the battery negative cable and set the radio stations.
POLICY: Reimbursable within the provisions of the warranty.
TIME ALLOWANCE:
Labor Operation No: 08-90-90-94 1.5 Hrs.
FAILURE CODE: BJ - Ground