LDP - MIL ON, DTC P1494 Set

NO: 18-27-98

GROUP: Vehicle Performance

DATE: Aug. 21, 1998

SUBJECT:

DTC $B8 And/Or
MIL Illumination

MODELS:

1997 - 1998 (ZJ) Grand Cherokee

NOTE:
THIS INFORMATION APPLIES TO VEHICLES EQUIPPED WITH A 5.2L OR 5.9L ENGINE WITH CALIFORNIA EMISSIONS SALES CODE NAE.

SYMPTOM/CONDITION:

DTC $B8 (P1494) - LEAK DETECTION PUMP SW OR MECHANICAL FAULT will be seen and the MIL can be illuminated. This could be caused by a partial vacuum blockage in the leak detection pump vacuum supply. Some vehicles may have the vacuum supply port (metal tube) at the intake manifold partially plugged due to a sealer used in the intake manifold casting to seal voids.

DIAGNOSIS:

If DTC $B8 is found, the vacuum supply line from the LDP to the intake manifold vacuum supply port (metal tube) must be checked for any restriction.

1. Remove the vacuum supply line at the LDP and connect a hand operated vacuum pump. Attempt to apply a vacuum to the line by operating the pump rapidly.

2. Watch the vacuum gauge and observe if any vacuum is being created. There should not be any restriction in the line and the gauge on the pump should not move from the 011 Hg position. If no vacuum is created, further diagnosis of the LDP system will be required.

3. If the gauge on the pump moves from the 0" Hg position, a determination will need to be made as to location of the restriction (LDP line or vacuum port on manifold).

4. Remove the LDP vacuum line from the intake manifold and attempt to apply a vacuum to the intake manifold port (metal tube). Follow the above procedures to decide if the restriction lies in the LDP line or manifold port.

If a restriction is found, perform the Repair Procedure.
PARTS/EQUIPMENT REQUIRED:

AR(1) 53030981AB Line, Vacuum LDP (All)

AR(1) NPN 5/32 Inch Drill Bit

REPAIR PROCEDURE:

This bulletin involves checking for and repairing restrictions in the LDP vacuum line.

1. If the restriction is found in the LDP vacuum line, replace the line with p/n 53030981AB.

2. If the restriction is found in the intake manifold vacuum port (metal tube), use the 5/32 inch drill bit and following procedure:

A. Wrap tape around the drill bit 1-1/2 inches from the tip. Wrap enough tape around the bit to prevent it from falling through the port and into the intake manifold.

B. Apply grease to the end of the drill bit to trap any debris that may be obstructing the port.

C. By hand, twist the drill bit (clockwise) into the port. Continue twisting the bit through the port until it is clear.

NOTE:
THE MANIFOLD PORT IS 1/4 INCH IN DIAMETER AND 1-1/4 INCHES LONG.

D. After the restriction is removed, spray solvent through the port to clean any remaining grease or gum.

3. Verify the repair by making sure the LDP vacuum line will not hold or allow any vacuum build as described in the diagnosis section.

POLICY: Reimbursable within the provisions of the warranty.

TIME ALLOWANCE:

Labor Operation No: 25-01-18-91 Repair Vacuum Port 0.3 Hrs.

25-01-18-92 Replace Vacuum Line 0.4 Hrs.

FAILURE CODE: XX - Service Adjustment