Grand Cherokee 4WD V8-5.2L VIN Y (1998)
Leak Detection Pump: All Technical Service Bulletins
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.
