QuestionHello Louis,
I have a 2000 Chrysler Cirrus and it has been a very good reliable car. Recently the check engine light came on. I paid to have the code checked into. They said they ran tests on the systems for the code and everything is working fine. They reset it and it came back on three days later. I am planning on going back in the near future but was hoping you might have a possible lead to what it could be. The code is:
Troubleshooting P1494
OEM Brand: Chrysler
Definition:
Evap Leak Detection pump pressure switch condition
Explanation:
ECM detected the leak detection pump switch did not change after the solenoid was energized
Probably Causes:
1. Leak detection pump defective
2. Open or shorted circuit condition
3. Solenoid defective
This is driving me crazy! Since being to the mechanic the last time we have noticed a few more issues creeping up such as:
There is a rattling metal sound when we first accelerate (the mechanic said that could be due to us needing a tune-up?)
The defrost button on the A/C comes on by itself even when the A/C is not on?
The dome light has started flickering and looking weak when we put it on while the car is still running.
We asked the mechanic to check the vacuum lines and they said they didn’t know where to start as it could be anywhere??
We had our car checked for a possible alternator problem too and they said its fine. Any advice you could offer would be wonderful. Thanks so much!
Vanessa :)
AnswerWell i can give you the test that the dealership techs would follow for this code but if this mechanic doesnt know maybe its time to swith shops but heres the test i have for that code
Symptom:
P-1494 LEAK DETECTION PUMP SW OR MECH FAULT
When Monitored and Set Condition:
P-1494 LEAK DETECTION PUMP SW OR MECH FAULT
When Monitored: Immediately after a cold start, with ambient temperature between 40
deg F and 90 deg F and coolant temperature within 10 deg F of ambient temperature.
Set Condition: The state of the leak detection pump switch is not in its expected state at
key-on (engine not running). Or, following an engine start, a change in switch state is not
seen when the LDP solenoid is energized to pull the pump diaphragm to its 9up9 position
POSSIBLE CAUSES
FUSED IGNITION SWITCH OUTPUT CIRCUIT OPEN
LDP PRESSURE SWITCH CIRCUIT SHORT TO GROUND
LDP SWITCH SENSE CIRCUIT OPEN
LDP WIRING AND/OR CONNECTORS OBSERVABLE DEF
LDP WIRING HARNESS INTERMITTENT FAILURE
LEAK OR OBSTRUCTION IN VAC HOSE
LEAK DETECTION PUMP DEFECTIVE
PCM DEF (LDP SYSTEM)
TEST ACTION APPLICABILITY
1 Start the engine.
With the DRBIIIt, perform the LEAK DETECT PUMP TEST.
Select “1” to PUMP, then select the down arrow to start the switch test (SW CHECK).
Does the LEAK DETECT PUMP SW STATE toggle from CLOSED (DN) to OPEN
(UP) during the SW CHECK?
All
Yes ® Go To 2
No ® Go To 4
2 Ignition Off
Using the schematic as a guide, inspect the Wiring and Connectors.
Were any problems found?
All
Yes ® Repair as necessary.
Perform Powertrain Verification Test VER-5A.
No ® Test Complete.
208
DRIVEABILITY
3 Start the Engine.
With the DRBIIIt, perform the LEAK DETECTION PUMP TEST.
Select “1” to PUMP, then select the down arrow to start the switch test (SW CHECK).
Wiggle the wiring harness from the Leak Detect Pump to the PCM, while monitoring
LEAK DETECT PUMP SW STATE on the DRBIII.
Does the LEAK DETECT PUMP SW STATE stop switching during the wiggle test?
All
Yes ® Repair as necessary.
No ® Go To 4
4 Ignition Off
Disconnect the Leak Detection Pump Connector.
Note: Check connectors - Clean/repair as necessary.
Key on.
With a Voltmeter, measure the Fused Ignition Switch Output Circuit.
Is the voltage above 10.0 volts?
All
Yes ® Go To 5
No ® Repair the open Fused Ignition Switch Output Circuit.
Perform Powertrain Verification Test VER-5A.
5 Ignition Off
Disconnect the Engine Vacuum Supply Hose at the Leak Detection Pump.
Install a Vacuum Gauge to Engine Vacuum Supply Hose at the Leak Detection Pump.
Start engine and read Vacuum Gauge.
Does Vacuum Gauge read within 1 inch of Engine Vacuum?
All
Yes ® Go To 6
No ® Repair leak or obstruction in Vacuum Hose.
Perform Powertrain Verification Test VER-5A.
6 Ignition Off
Disconnect the PCM.
Disconnect the Leak Detect Pump Connector.
Note: Check connectors - Clean/repair as necessary.
Using an Ohmmeter, measure the resistance of the LDP Pressure Switch Circuit
from the PCM Connector to a good ground.
Is the resistance below 5.0 ohms?
All
Yes ® Repair LDP Pressure Switch Circuit for a short to ground.
Perform Powertrain Verification Test VER-5A.
No ® Go To 7
7 Ignition Off
Disconnect the PCM.
Note: Check connectors - Clean/repair as necessary.
Disconnect the Leak Detection Pump Connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the LDP Pressure Switch Sense Circuit from the PCM
Connector to LDP Connector.
Is the resistance below 5.0 ohms?
All
Yes ® Go To 8
No ® Repair the open Leak Detection Pump Switch Sense Circuit.
Perform Powertrain Verification Test VER-5A.
209
DRIVEABILITY
TEST ACTION APPLICABILITY
8 Ignition Off
Disconnect the PCM.
Note: Check connectors - Clean/repair as necessary.
Key on.
With voltmeter connected to LDP Switch Sense Circuit at PCM Connector, ground
the LDP Solenoid Control Circuit.
While applying vacuum to LDP with a hand vacuum pump, observe voltmeter.
Did voltage change?
All
Yes ® Go To 9
No ® Replace the LDP.
Perform Powertrain Verification Test VER-5A.
9 If there are no potential causes remaining.
View repair options.
All
Repair
Replace the PCM.
Perform Powertrain Verification Test VER-5A.
210
DRIVEABILITY
P-1494 LEAK DETECTION PUMP SW OR MECH FAULT — Continued
