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Here is the flow chart starting point for this code; it may just be a vacuum line to the LDP, or other possible causes, listed; the LDP itself, is not cheap, so a complete diag. should be preformed , before throwing parts at it. I will also include a pic of the location, at the end, so you can at least check for vacuum.
P1494-LEAK DETECTION PUMP SW OR MECHANICAL FAULT
When Monitored and Set Condition:
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/
Set Condition: The state of the switch does not change when the solenoid is energized.
VEHICLE HISTORY AND SERVICE BULLETIN INVESTIGATION
LDP SWITCH SENSE CIRCUIT SHORTED TO GROUND
WIRING HARNESS INTERMITTENT
LDP VACUUM SUPPLY
FAULTY LEAK DETECTION PUMP
LDP SWITCH SENSE CIRCUIT OPEN
POWERTRAIN CONTROL MODULE
TEST ACTION APPLICABILITY
1 Start by reading PCM DTC(s) and record the related Freeze Frame data if any
DTC(s) are present.
Check the vehicle repair history.
If the vehicle has a repair history that pertains to the customer's current complaint,
review the repair.
NOTE: Replacing the PCM will not correct this problem.
Inspect the vehicle for any aftermarket accessories that may have been installed
Check for any service bulletin(s) related to the customer's complaint or DTC(s).
If a service bulletin applies, follow the instructions per service bulletin.
Did the service bulletin repair the customer's complaint?
Yes ! Testing Complete.
Perform POWERTRAIN VERIFICATION TEST VER - 6.
No ! Go To 2
2 Ignition on, engine not running.
With the DRBIIIt, read DTCs and record the related Freeze Frame data.
Is the DTC Good Trip Counter displayed and equal to zero for P-1494?
Yes ! Go To 3
No ! Go To 8
The Leak Detection Pump (LDP) is located under the left quarter panel behind the left/rear wheel (LOCATION, LDP / EVAP CANISTER). It is attached to a two-piece support bracket (TWO-PIECE SUPPORT BRACKET). The LDP and LDP filter are replaced (serviced) as one unit.