NO:18-01-00
SUBJECT:Misdiagnosed Leak Detection Pump Systems With DTC P1494, P0442, P0455, OR P0456
DATE:Feb. 4, 2000
DISCUSSION:
During evaporative system diagnosis, Leak Detection Pumps have mistakenly been replaced. A thorough inspection for pinched, kinked, or disconnected supply vacuum lines (as currently listed in the Powertrain Diagnostic Procedures) is a critical step in diagnosing DTC P1494 (LDP SW OR MECHANICAL FAULT). Additionally, the other evaporative leak faults (DTC P0442 - SMALL LEAK, P0455 - LARGE LEAK, and P0456 - VERY SMALL LEAK) should have the supply vacuum lines examined for pinches or kinks prior to any LDP component replacement.
The supply vacuum lines should be checked from the engine compartment all the way to the fuel tank, including the LDP and purge system.
NOTE: VERIFY ALL RELATED SUPPLY VACUUM LINE ROUTINGS FOR PINCHES, KINKS, OR DISCONNECTION'S BEFORE REPLACING LDP SYSTEM COMPONENTS.
POLICY:Information Only
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NO:18-27-98
SUBJECT:DTC $B8 And/Or MIL Illumination
DATE:Aug. 21, 1998
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 P1494 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 shouldnotbe any restriction in the line and the gauge on the pump should not move from the 0" 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 REQUIRED:
Qty / Part No. / DescriptionAR(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 ½ 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 ¼ INCH IN DIAMETER AND 1 ¼ 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 Op. No. / Description / Time25-01-18-91 / Repair Vacuum Port / 0.3 Hrs.
25-01-18-92 / Replace Vacuum Line / 0.4 Hrs.
FAILURE CODE:
Code / DescriptionXX / Service Adjustment