Results 1 to 8 of 8

Thread: P1495 code

  1. #1

    Default P1495 code

    I was on my way home tonight and the check engine light came on. When I got home and did the on/off with the key to display the code it gave a P1495 code. I looked it up and it said it was a leak detection pump solenoid circuit. Does anyone know how to fix this and how costly it might be? Thanks for any help.

  2. #2
    Registered
    Join Date
    Jan 2010
    Location
    Virginia, USA
    Posts
    213

    Default

    What year and engine ? here is the allahdata bulletin for a 03 WJ V8 (P1495)

    --

    SYMPTOM
    P1495-LEAK DETECTION PUMP SOLENOID CIRCUIT

    WHEN MONITORED
    Ignition on and battery voltage greater than 10.4 Volts .

    SET CONDITION
    The state of the solenoid circuit does not match the PCM's desired state.

    POSSIBLE CAUSES

    * Vehicle History and Service Bulletin Investigation
    * Generator source circuit open
    * Leak detection pump solenoid control circuit open
    * LDP solenoid control circuit shorted to ground
    * Leak detection pump
    * Wiring Harness Intermittent
    * Powertrain control module
    Attached Images Attached Images

  3. #3
    Registered
    Join Date
    Jan 2010
    Location
    Virginia, USA
    Posts
    213

    Default

    ENABLING CONDITIONS TO RUN EVAP LEAK DETECTION TEST

    * Cold start: with ambient temperature (obtained from modeling the inlet air temperature sensor on passenger vehicles and the battery temperature sensor on Jeep & Dodge Truck vehicles) between 4 C (40 F) and 32 C (90 F) for 0.040 leak. Between 4 C (40 F) and 29 C (85 F) for 0.020 leak.
    * Engine coolant temperature within: -12to -8 C (10to 18 F) of battery/ambient.
    * Battery voltage between 10 and 15 volts .
    * Low fuel warning light OFF (fuel level must be between 15% and 85%.
    * MAP sensor reading 22 in Hg or above (This is the manifold absolute pressure, not vacuum).
    * No engine stall during test.

    NOTE:

    * IF BATTERY VOLTAGE DROPS BELOW 10 VOLTS FOR MORE THAN 5 SECONDS DURING ENGINE CRANKING, THE EVAP LEAK DETECTION TEST WILL NOT RUN.
    * THE FOLLOWING VALUES ARE APPROXIMATE AND VEHICLE SPECIFIC. USE THE VALUES SEEN IN PRE TEST/MONITOR TEST SCREEN ON THE DRB III. SEE TSB 25-02-98 FOR MORE DETAIL.

    A DTC will not be set if a one-trip fault is set or if the MIL is illuminated for any of the following:

    * Purge Solenoid Electrical Fault
    * All TPS Faults
    * All Engine Controller Self Test Faults
    * LDP Pressure Switch Fault
    * All Cam and/or Crank Sensor Fault
    * EGR Solenoid Electrical Fault
    * All MAP Sensor Faults
    * All Injector Faults
    * Ambient/Battery Temperature Sensor Electrical Faults
    * Baro Out of Range
    * Vehicle Speed Faults
    * All Coolant Sensor Faults
    * LDP Solenoid Circuit

    NOTE: IF BATTERY TEMPERATURE IS NOT WITHIN RANGE, OR IF THE ENGINE COOLANT TEMPERATURE IS NOT WITHIN A SPECIFIED RANGE OF THE BATTERY TEMPERATURE, THE PCM WILL NOT RUN TESTS FOR DTC P1494, P1486, P0442, P0455 AND P0441. THESE TEMPERATURE CALIBRATIONS MAY BE DIFFERENT BETWEEN MODELS.

    SECTION 1 - P1495 Leak Detection Pump Solenoid Circuit - When the ignition key is turned to "ON", the LDP diaphragm should be in the down position and the LDP reed switch should be closed. If the EVAP system has residual pressure, the LDP diaphragm may be up. This could result in the LDP reed switch being open when the key is turned to "ON" and a P1494 fault could be set because the PCM is expecting the reed switch to be closed.

    After the key is turned "ON", the PCM immediately tests the LDP solenoid circuit for electrical faults. If a fault is detected, DTC P1495 will set, the MIL will illuminate, and the remaining EVAP Leak Detection Test is canceled.

    SECTION 2 - P1494 Leak Detection Pump Switch or Mechanical Fault- If DTC P1495 is not set, the PCM will check for DTC P1494. If the LDP reed switch was closed when the key was turned to "ON", the PCM energizes the LDP solenoid for up to 8 seconds and monitors the LDP switch. As the LDP diaphragm is pulled up by engine vacuum, the LDP reed switch should change from closed to open. If it does not, the PCM sets a temporary fault (P1494) in memory, and waits until the next time the Enabling Conditions are met to run the test again. If this is again detected, P1494 is stored and the MIL is illuminated. If the problem is not detected during the next enabling cycle, the temporary fault will be cleared.

    However, if the PCM detects the reed switch open when the key is turned to "ON", the PCM must determine if this condition is due to residual pressure in the EVAP system, or an actual fault. The PCM stores information in memory on EVAP system purging from previous engine run or drive cycles.

    If little or no purging took place, residual pressure could be holding the LDP diaphragm up, causing the LDP switch to be open. Since this is not a malfunction, the PCM cancels the EVAP Leak Detection Test without setting the temporary fault.

    If there was sufficient purging during the previous cycle to eliminate EVAP system pressure, the PCM judges that this is a malfunction and sets a temporary fault in memory. The next time that the Enabling Conditions are met, the test will run again. If the fault is again detected, the MIL will illuminate and DTC P1494 will be stored. If the fault is not detected, the temporary fault will be cleared.

    SECTION 3 - P1486 EVAP Leak Monitor Pinched Rose Found- If no fault has been detected so far, the PCM begins testing for possible blockage in the EVAP system between the LDP and the fuel tank. This is done by monitoring the time required for the LDP to pump air into the EVAP system during two to three pump cycles. If no blockage is present, the LDP diaphragm is able to quickly pump air out of the LDP each time the PCM turns OFF the LDP solenoid. If a blockage is present, the PCM detects that the LDP takes longer to complete each pump cycle. If the pump cycles take longer than expected (approximately 6 to 10 seconds) the PCM will suspect a blockage. On the next drive when Enabling Conditions are met, the test will run again. If blockage is again detected, P1486 is stored, and the MIL is illuminated.

    SECTION 4 - No DTC Can Be Set During This Time- After the LDP blockage tests are completed, the PCM then tests for EVAP system leakage. First, the PCM commands the LDP to rapidly pump for 20 to 50 seconds (depending on fuel level) to build pressure in the EVAP system. This evaluates the system J18-24-0 to see if it can be sufficiently pressurized. This evaluation (rapid pump cycling) may occur several times prior to leak checking. The LDP reed switch does not close and open during rapid pumping because the diaphragm does not travel through its full range during this part of the test.

    SECTION 5 - P0456, P0442, P0455 EVAP Leak Monitor and Leak Detected- Next, the PCM performs one or more test cycles by monitoring the time required for the LDP reed switch to close (diaphragm to drop) after the LDP solenoid is turned OFF.

    If the switch does not close, or closes after a long delay, it means that the system does not have any significant leakage and the EVAP Leak Detection Test is complete.

    However, if the LDP reed switch closes quickly there may be a leak or the fuel level may be low enough that the LDP must pump more to finish pressurizing the EVAP system. In this case, the PCM will rapidly pump the LDP again to build pressure in the EVAP system, and follow that by monitoring the time needed for several LDP test cycles. This process of rapid pumping followed by several LDP test cycles may repeat several times before the PCM judges that a leak is present.

    When leaks are present, the LDP test cycle time will be inversely proportional to the size of the leak. The larger the leak, the shorter the test cycle time. The smaller the leak, the longer the test cycle time. DTC's may be set when a leak as small as 0.5 mm (0.020") diameter is present.

    If the system detects a leak, a temporary fault will be stored in PCM memory. The time it takes to detect a 0.020, 0.040, or Large leak is based on calibrations that vary from model to model. The important point to remember is if a leak is again detected on the next EVAP Leak Detection Test, the MIL will illuminate and a DTC will be stored based on the size of leak detected. If no leak is detected during the next test, the temporary fault will be cleared.

    DIAGNOSTIC TIPS During diagnosis, you can compare the LDP solenoid activity with the monitor sequence in Figure 6. If the PCM detects a problem that could set a DTC, the testing is halted and LDP solenoid activity will stop. As each section of the test begins, it indicates that the previous section passed successfully. By watching to see which tests complete, you can see if any conditions are present that the PCM considers abnormal.

    For example, if the LDP solenoid is energized for the test cycles to test for blockage (P1486), it means that the LDP has already passed its test for P1494. Then, if the PCM detects a possible blockage, it will set a temporary fault without turning ON the MIL and continue the leak portion of the test. However, the PCM will assume that the system is already pressurized and skip the rapid pump cycles.

    Always diagnose leaks, if possible, before disconnecting connections. Disconnecting connections may mask a leak condition.

    Keep in mind that if the purge solenoid seat is leaking, it could go undetected since the leak would end up in the intake manifold. Disconnect the purge solenoid at the manifold when leak checking. In addition, a pinched hose fault (P1486) could set if the purge solenoid does not purge the fuel system properly (blocked seat). The purge solenoid must vent the fuel system prior to the LDP system test. If the purge solenoid cannot properly vent the system the LDP cannot properly complete the test for P1486 and this fault can set due to pressure being in the EVAP system during the test sequence.

    Multiple actuation's of the DRB III Leak Detection Pump (LDP) Monitor Test can hide a 0.020 leak because of excess vapor generation. Additionally, any source for additional vapor generation can hide a small leak in the EVAP system. Excess vapor generation can delay the fall of the LDP diaphragm thus hiding the small leak. An example of this condition could be bringing a cold vehicle into a warm shop for testing or high ambient temperatures.

    Fully plugged and partially plugged underhood vacuum lines have been known to set MIL conditions. P1494 and P0456 can be set for this reason. Always, thoroughly, check plumbing for pinches or blockage before condemning components.

    TEST EQUIPMENT The Evaporative Emission Leak Detector (EELD) Miller Special Tool 8404 is capable of visually detecting leaks in the evaporative system and will take the place of the ultrasonic leak detector 6917A. The EELD utilizes shop air and a smoke generator to visually detect leaks down to 0.020 or smaller. The food grade oil used to make the smoke includes an UV trace dye that will leave telltale signs of the leak under a black light. This is helpful when components have to be removed to determine the exact leak location. For detailed test instructions, follow the operators manual packaged with the EELD.

    NOTE: Be sure that the PCM has the latest software update. Reprogram as indicated by any applicable Technical Service Bulletin. After LDP repairs are completed, verify the repair by running the DRB III Leak Detection Pump (LDP) Monitor Test as described in Technical Service Bulletin 18-12-99.
    Attached Images Attached Images

  4. #4
    Registered
    Join Date
    Jan 2010
    Location
    Virginia, USA
    Posts
    213

    Default

    REMOVAL
    The Leak Detection Pump (LDP) is located under the left quarter panel behind the left/rear wheel. It is attached to a two-piece support bracket. The LDP and LDP filter are replaced (serviced) as one unit.

    1.Remove stone shield behind left/rear wheel. Drill out plastic rivets for removal.
    2. Remove 3 LDP mounting bolts.
    3. Remove support bracket brace bolt.
    4. Loosen, but do not remove 2 support bracket nuts at frame rail.
    5. To separate and lower front section of two-piece support bracket, remove three attaching bolts on bottom of support bracket. While lowering support bracket, disconnect LDP wiring clip.
    6. Disconnect electrical connector at LDP.
    7. Carefully remove vapor/vacuum lines at LDP.
    8. Remove LDP.

    INSTALLATION
    The LDP is located in the left quarter panel behind the left/rear wheel. It is attached to a two-piece support bracket. The LDP and LDP filter are replaced (serviced) as one unit.

    1. Position LDP and carefully install vapor/vacuum lines to LDP and LDP filter. The vapor/vacuum lines and hoses must be firmly connected. Check the vapor/vacuum lines at the LDP, LDP filter and EVAP canister purge solenoid for damage or leaks. If a leak is present, a Diagnostic Trouble Code (DTC) may be set.
    2. Connect electrical connector to LDP.
    3. While raising front section of support bracket, connect LDP wiring clip.
    4. Install 3 LDP mounting bolts. Refer to Torque Specifications.
    5. Join front and rear sections of two-piece support bracket by installing 3 bolts on bottom of support bracket. Do not tighten bolts at this time.
    6. Install support bracket brace bolt. Do not tighten bolt at this time.
    7. Tighten 2 support bracket nuts at frame rail. Refer to Torque Specifications.
    8. Tighten 3 support bracket bolts and brace bolt. Refer to Torque Specifications.
    9. Position stone shield behind left/rear wheel. Install new plastic rivets.
    Attached Images Attached Images
    Last edited by hexonut; 01-14-2010 at 01:29 AM.

  5. #5
    Registered
    Join Date
    May 2000
    Location
    Richmond, VA
    Posts
    214

    Default

    I had the same problem. Solution was reattaching a vacuum hose to the intake manifold, common cause of P1495. The disconnect was hard to find until I removed the air filter top and disconnected it from the throttle body. 15 minutes (after I tried everything else) and free! This was on an 01 WJ 4.0.

  6. #6

    Default

    Sorry I forgot to mention it's the 4.0L engine and it's a 2004. I'll check the hoses. That install sounds like a pain in the ass.

  7. #7
    Registered
    Join Date
    Jan 2010
    Location
    Virginia, USA
    Posts
    213

    Default

    yeah Allah data gives basically the same procedure for the 4.0 and the pump is of course located in the same location.

    surely a smoke-test is in order but the money you spend on having it tested will take away from the money you need to buy a new pump.

    I would check visually all the vacuum lines for the system first but you are not getting a (small or large) leak code, your detection pump is not sensing if there is a leak or not... this points directly to the pump.

  8. #8

    Default

    well the problem ended up being a wire that corroded and broke thus no power going back to the pump. It almost looked like someone punctured the wire during a test and didn't seal the holes or something. It was a pain in the ass to find. Thanks for all the info on this though.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Jeep Parts | Jeep Accessories | Trektop NX | Jeep Seat Covers | Jeep Wrangler | Jeep Wrangler Parts | Jeep Wrangler Accessories | Bestop | Jeep Tires | Jeep Stuff | Jeep Wrangler Tires | Jeep Wheels