[c180]

Symptom:
P1494-LEAK DETECTION PUMP SW OR MECHANICAL FAULT
When Monitored and Set Condition:
P1494-LEAK DETECTION PUMP SW OR MECHANICAL FAULT
When Monitored: Immediately after a cold start, with battery/ambient temperature
between 40 deg. F and 90 deg. F and coolant temperature within 10 deg. F of battery/
ambient.
Set Condition: The state of the switch does not change when the solenoid is energized.
POSSIBLE CAUSES
WIRING HARNESS INTERMITTENT
LDP SWITCH SENSE CIRCUIT SHORTED TO GROUND
LDP VACUUM SUPPLY
LEAK DETECTION PUMP
LDP SWITCH SENSE CIRCUIT OPEN
POWERTRAIN CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, read DTC’s.
Is the DTC Good Trip Counter displayed and equal to zero for P-1494?
All
Yes ® Go To 2
No ® Go To 7
2 Turn the ignition off.
Disconnect the vacuum supply hose at the Leak Detection Pump.
Connect a vacuum gauge to the disconnected vacuum supply hose at the Leak
Detection Pump.
Start the engine and read the vacuum gauge.
Does the vacuum gauge read at least 13 in/Hg?
All
Yes ® Go To 3
No ® Repair leak or obstruction in vacuum hose as necessary.
Perform POWERTRAIN VERIFICATION TEST VER - 6.
176
DRIVEABILITY - GAS
TEST ACTION APPLICABILITY
3 Turn the ignition off.
Disconnect the Leak Detection Pump harness connector.
Disconnect the PCM harness connector(s).
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the LDP Switch Sense Circuit from the PCM harness
connector to LDP harness connector.
Is the resistance below 5.0 ohms?
All
Yes ® Go To 4
No ® Repair the open Leak Detection Pump Switch Sense Circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 6.
4 Turn the ignition off.
Disconnect the Leak Detection Pump electrical harness connector.
Turn the ignition on.
With the DRBIIIt in Inputs/Outputs, read the 9Leak Detect Pump Sw9 state.
While observing the 9Leak Detect Pump Sw9 state, connect a jumper wire between a
good 12 volt source (B+) and the LDP Switch Sense circuit.
Did the 9Leak Detect Pump Sw9 state change when the jumper was connected?
All
Yes ® Replace the Leak Detection Pump.
Perform POWERTRAIN VERIFICATION TEST VER - 6.
No ® Go To 5
5 Turn the ignition off.
Disconnect the Leak Detection Pump electrical harness connector.
Disconnect the PCM harness connector(s).
Measure the resistance between the LDP Switch Sense circuit and ground.
Is the resistance below 5.0 Ohms?
All
Yes ® Repair the LDP Switch Sense Circuit for a short to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 6.
No ® Go To 6
6 If there are no possible causes remaining, view repair. All
Repair
Replace the Powertrain Control Module.
Perform POWERTRAIN VERIFICATION TEST VER - 6.
7 At this time, the conditions required to set the DTC are not present.
Note: Use the Freeze Frame Data to help you duplicate the conditions that
set the DTC. Pay particular attention to the DTC set conditions, such as,
VSS, MAP, ECT, and Load.
Note: Visually inspect the related wiring harness. Look for any chafed,
pierced, pinched, or partially broken wires.
Note: Visually inspect the related wire harness connectors. Look for broken,
bent, pushed out, or corroded terminals.
Note: Refer to any Technical Service Bulletins (TSB’s) that may apply.
Perform a wiggle test of the LDP wiring while the circuit is actuated with the
DRBIIIt. Listen for the LDP to quit actuating. Also watch for the Good Trip Counter
to change to 0.
Were any problems found?
All
Yes ® Repair wiring harness/connectors as necessary.
Perform POWERTRAIN VERIFICATION TEST VER - 6.
No ® Test Complete.