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Range Rover P38 4.0 THOR Cuts Out

Discussion in 'Range Rover' started by Dylan Banachowicz, Mar 19, 2021.

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  1. brianp38dse

    brianp38dse Well-Known Member

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    upload_2021-4-15_12-42-11.jpeg
     
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  2. brianp38dse

    brianp38dse Well-Known Member

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    Has the crank position sensor been checked as they fail when warm then cool down and work
    a good test is run it up when it cuts out spray some plumbers freeze spray on it if it then works bingo, or change it to rule it out.
     
  3. Dylan Banachowicz

    Dylan Banachowicz Member

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    I did think about that but the engine light does not illuminate when the issue arises, also the idle air control valve stops humming as it’s totally lost it’s supply or ground. If I unplug the crank sensor, the engine light illuminates. I’m positive the issue is with the engine ECU getting too hot and shutting down, just need to know at what temperature the fan should run then I can monitor the E-box temperature and see what we get. I opened the ECU up and inspected it with a 400x magnifier to check for dry solder joints, but no issue found.
     
  4. brianp38dse

    brianp38dse Well-Known Member

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    Humm a strange one is this
     
  5. Grrrrrr

    Grrrrrr Technician, Bodgit & Scarper Ltd Full Member

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    Cam sensor? I have a vague memory if one fails the CEL doesn't come on.
     
  6. pwood999

    pwood999 Well-Known Member Full Member

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    Look for swollen capacitors on the ECU board. If you can take a high resolution photo of both sides of the board & upload.

    Also try keeping diagnostics connected & logging while it's running. Then possibly you might get an error just as it cuts out ?

    I tend to agree on your temperature hypothesis but finding it will be the challenge.
     
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  7. Dylan Banachowicz

    Dylan Banachowicz Member

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    Would be a nice quick fix but it’s definitely the ECU shutting down due to temperature. If it was a sensor, then that would be show when the ECU is scanned, but no fault codes show except for P1669 (E-box cooling fan open circuit) which I have caused by bypassing the engine ECU to allow the fan to run constantly. Also, when the fault occurs, you can’t access the engine ECU with a scan tool, it’s as if the ignition is off but everything else is live and working.
     
  8. pwood999

    pwood999 Well-Known Member Full Member

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    Yes I understand you cannot read faults after it cuts out, but capture all the main live sensor data to log file while it's running. Then look at the last few logged readings after the cutout. There might be a clue in the values as it dies ?
     
  9. JUKE179r

    JUKE179r Well-Known Member Full Member

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    I concur with thinking it’s a CPS issue.
    I had the CPS on my Disco 2 fail in the middle of traffic in 101 degree weather. I had to pour bottled water onto the sensor area to cool down and restart to get it out of traffic.
    @Dylan Banachowicz ... the next time you drive your P38 and it dies on you, try to restart it and notice if the tachometer works. If it doesn’t work, it is a bad crank position sensor. Buy a Bosch ERR-735.
     
    Last edited: Apr 16, 2021
  10. Dylan Banachowicz

    Dylan Banachowicz Member

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    I will give it a try. But surly if the CPS fails, I should get a fault code? Also I should still be able to access the engine ECU with a scan tool while the issue is present but I can’t. I will disconnect the E-box cooling fan today and see if it cuts out while on the drive. Still need to find out if the engine ECU has a temperature cut out to prevent it burning up.
     
  11. Dylan Banachowicz

    Dylan Banachowicz Member

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    I will give it a try. I will monitor ECU volts as well and see what happens.
     
  12. Grrrrrr

    Grrrrrr Technician, Bodgit & Scarper Ltd Full Member

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    Have a look in RAVE. On the GEMS I am pretty sure that when one of the sensors fails you get no error code and it might be CPS. Thor might be the same.
     
  13. Dylan Banachowicz

    Dylan Banachowicz Member

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    Thanks for the info. I will unplug the sensor when running and see if I get a fault code. But I should still be able to access the ECU which I can’t. Will let you know.
     
  14. pwood999

    pwood999 Well-Known Member Full Member

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    Form Bosch 521 System Doc:

    The signal produced by the crankshaft position sensor is critical to engine running. There is no
    backup strategy for this sensor and failure of the signal will result in the engine stalling and/or
    failing to start. If the sensor fails when the engine is running, then the engine will stall, a fault
    code will be stored and details captured, of the battery voltage, coolant temperature and air
    temperature at the time of the failure. If the signal fails when the engine is cranking, then the
    engine will not start and no fault will be stored, as the ECM will not detect that an attempt had
    been made to start the engine. In both cases the tachometer will also cease to function
    immediately and the MIL lamp will not extinguish.
     
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  15. Dylan Banachowicz

    Dylan Banachowicz Member

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    Will I’ve unplugged both the crank and cam position sensors in turn.

    1 - Cam sensor unplugged - Engine starts as normal, no EML light but fault code P0340 (cam position sensor) stored in the ECU.

    2 - Crank sensor unplugged - Engine no start, as per the above post, no fault stored.

    neither replicate the issue I have.
    I now have a temperature sensor in the E-box monitoring the ECU temperature with the cooling fan disconnected and I am monitoring volts on the fan control wire at the ECU to see at what point if any, the fan is called to run.
     
  16. Dylan Banachowicz

    Dylan Banachowicz Member

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    Hopefully the last update......all test carried out with the Range Rover stationary....

    So I disconnected the E-box cooling fan and ran the engine with bonnet closed to generate lots of heat in the engine bay while monitoring the temperature in the E-box. It took some time but the E-box eventually reached a temperature of 67C at which point, the engine cut out, gearbox faulty was displayed and no engine light on the dash. I opened the bonnet and the E-box and allowed it to cool to 60C at which point the engine started again. Repeated the above and yet again the engine cut out when the E-box reached 67C. I then connected the cooling fan so it was running constantly and repeated the test again. This time the E-box only achieved at temperature of 40C, no amount of revs could raise the temperature above 40C. Next I reconnected the cooling fan to the ECU so it would be controlled bu the engine ECU. I repeated the test again and the E-box temperature rose to 60C at which point the cooling fan cut in!!! The temperature then fell to 36C at which point the fan cut out. I repeated this several time with no issues with the engine cutting out. I can only conclude that maybe the cooling can had seized as the Range Rover had been parked up for some time, and it wound be very rare for the E- box temperature to reach 60C to call for the fan to run. I will monitor the E-box temperature over the next week during normal driving, but I don’t expect to see temperatures anywhere near that high through normal driving. Maybe stuck in traffic for over an hour in the middle of summer may get near!!!!
     
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  17. DanClarke

    DanClarke Well-Known Member Full Member

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    Sounds wonderful. At what point did the fault get fixed? Change of fan? Change of temp sensor? Other? I am a bit thick so confused. ;)
     
  18. Dylan Banachowicz

    Dylan Banachowicz Member

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    I suspect the cooling fan was a little seized. The fan is controlled by the engine ECU so no temperature sensor to change. The fan motor is very small, about 20mm in diameter, and very low powered so wouldn’t take much to jam the motor. I removed it and connected it directly to the battery and it ran. If it was a poor connection, the ECU would show a fault code of P1669 as I discovered earlier when I bypassed the ECU to run the fan constantly. I bet the fan hardly ever runs as the E-box temperature needs to be 60C for the fan to run.
     
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  19. DanClarke

    DanClarke Well-Known Member Full Member

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    Thanks! :)
     
  20. brianp38dse

    brianp38dse Well-Known Member

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    Well i think we have all learned something new there:D
    well done for working it out can not have been easy:)
     
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