Volvo AWD 850 Forum

INDEX FOR 10/2025(CURRENT) INDEX FOR 9/2005 850 INDEX

[<<]  [>>]


THREADED THREADED EXPANDED FLAT PRINT ALL
MESSAGES IN THIS THREAD




  REPLY TO THIS MESSAGE Replies to this message will be emailed.    PRINT   SAVE 

855 t5 eating ECT sensors 850

posted by  5tovlov on  Wed Feb 23 02:55 CST 2005
Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS] [RELATED]

Hi Guys
> At wits end with my car, I've had it to dealers twice in the last few
> weeks with a failed water coolant sensor, first time it went got all
> kinds of strange problems revving engine lights fading ABS light on
so
> took it to volvo who read code 123 replaced the temp sensor and all
> was well for 2 weeks, dreaded lambda light came on (no symptoms car
> was running perfectly) so I pulled over switched off the engine
> cooling fan remained on car would not start again, the AA arrived 90
> minutes later and the car started no problems, temp gauge went to 3
> o'clock cooling fan ran constantly, drove to volvo no problems
> whatsoever other than cooling fan running constantly, volvo said "ok
> maybe a faulty sensor" they fitted a new thermostat and a new sensor
> and sent me on my way all was well for a month then exact same thing
> happened light on cooling fan stayed on, so I bought a sensor myself
> and fitted it, it ran for 15 mins before wrecking the new sensor,
> checked all the wiring apart from a tiny nic in the wire at the
> connection all seemed ok, tested the voltage coming from ECU and it
> reads around 5 volts, Volvo now want to fit a new ECU although they
> admit that this might not be the problem, anybody got any ideas, or
> should I go for ECU replacement.............please help I love my T5
> dearly







  •   REPLY TO THIS MESSAGE    PRINT   SAVE 

    855 t5 eating ECT sensors 850

    posted by  Hamfisted on  Wed Feb 23 05:32 CST 2005
    Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS] [RELATED]

    How big was the "nic" in the wire? If it is causing intermittent contact it needs to be repaired. Do you have a digital multimeter? You can do some tests on your own. At 80 degrees the resistance across the sensor contacts should be about 2300 ohms.


    Mike




    Code 1-2-3 (Engine Coolant Temperature Sensor Signal)

    1) If ECM receives a signal from ECT sensor which indicates a
    temperature less than -49 �� F (-45 �� C), or greater than 300 �� F (150 �� C),
    this is interpreted as a fault and DTC 1-2-3 is set.

    2) If Codes 3-1-4, 4-1-1, and/or 4-1-3 are set, check ECT
    sensor, CMP sensor, TP sensor, and EGR temperature sensor joint
    connector terminal A18 on ECM for signs of contact resistance and/or
    oxidation. If no other codes are stored, go to next step.

    3) If fault is permanent, go to next step. If fault is
    intermittent and signal is too high, check all connectors for an
    intermittent open or short circuit to voltage. If fault is
    intermittent and signal is too low, check wiring between ECT sensor
    connector terminal No. 1 and ECM terminal A31 for an intermittent
    short to ground.

    4) If fault is permanent and signal is too low, go to step
    10). If fault is permanent and signal is too high, turn ignition off.
    Wait 90 seconds, then disconnect ECT sensor. Connect an ohmmeter
    between ECT sensor connector No. 2 and ground.
    NOTE: Fan run-on must be allowed to finish before taking
    resistance measurements.

    5) If ohmmeter shows about zero ohms, go to next step. If
    ohmmeter does not show about zero ohms, go to step 7).

    6) Turn ignition on. Disconnect ECT sensor connector. Connect
    voltmeter between ECT sensor connector terminal No. 1 and 2. If
    voltmeter shows about 5 volts, go to step 8). If voltmeter shows about
    zero volts, go to step 9). If voltmeter shows more than about 5 volts,
    check wiring between ECT sensor connector terminal No. 1 and ECM
    terminal A31 for a short to voltage, then check resistance between ECT
    sensor terminals. Ohmmeter should show about 2200 ohms. If resistance
    is incorrect, retest using a known good ECT sensor.

    7) Ensure ignition is off. Disconnect ECT sensor connector.
    Check ECM connector for poor contact and/or oxidation. Reconnect ECM
    connector. Connect an ohmmeter between ECT sensor connector terminal
    No. 2 and ground. If ohmmeter shows about zero ohms, code is caused by
    poor contact in ECM connector. If ohmmeter does not show about zero
    ohms, check wiring between ECT sensor connector terminal No. 2 and ECM
    terminal A18 for an open circuit.

    8) Ensure ignition is off. Disconnect ECT sensor connector.
    Connect an ohmmeter between ECT sensor connector terminals No. 1 and
    2. If ohmmeter does not show about 2200 ohms, repeat test using a
    known good ECT sensor. If ohmmeter does show about 2200 ohms, check
    for poor contact at ECT sensor connector.

    9) Ensure ignition is off. Disconnect ECT sensor connector.
    Ensure ECM connector has good terminal contact. Reconnect ECM
    connector. Turn ignition on. Connect voltmeter between ECT sensor
    connector terminals No. 1 and 2. If voltmeter shows about 5 volts,
    check for poor contact at ECM connector. If voltmeter does not show
    about 5 volts, check wiring between ECT sensor connector terminal No.
    1 and ECM connector terminal A31 for an open circuit.

    10) If fault is permanent and signal is too low, turn
    ignition off. Disconnect ECT sensor. Turn ignition on. Connect
    voltmeter between ECT sensor connector terminal No. 1 and ground. If
    voltmeter shows about 5 volts, retest system using a known good ECT
    sensor. If voltmeter does not show about 5 volts, check wiring between
    ECT sensor terminal No. 1 and ECM connector terminal A31 for a short
    to ground.







<< < > >>



©Jarrod Stenberg 1997-2022. All material except where indicated.


All participants agree to these terms.

Brickboard.com is not affiliated with nor sponsored by AB Volvo, Volvo Car Corporation, Volvo Cars of North America, Inc. or Ford Motor Company. Brickboard.com is a Volvo owner/enthusiast site, similar to a club, and does not intend to pose as an official Volvo site. The official Volvo site can be found here.