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1998 Mercedes-Benz ML320 Question: locks won't lock/unlock w/remote OR console button. alarm sets/disarms

 

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charlie320, Sanford, NC, February 28, 2014, 13:57
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lights flash & all relays work

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  • Answer #1

    G. T. Service Center (4142 Answers) , Stephenville, TX - (254) 638-3236
    ProfessorG February 28, 2014, 17:17
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    possible door lock actuators or wiring to them. Test the power and ground at the actuators or the clips that attach to the locking mechanism.

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    charlie320, March 01, 2014, 15:00
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    both wires @ actuator go directly to ground. when remote or console is contacted ,voltage @ actuator solenoid is 0.2volts

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    ProfessorG, March 01, 2014, 16:54
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    What resistance reading is in the ground.

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    charlie320, March 02, 2014, 17:13
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    o ohms to ground. this was checked @ fuel door actuator. when disconnected I get full voltage upon actuating key fob & console button. same result @ rear hatch lock. however I tried applying 12 volts directly to fuel door solenoid (changing polarities) & it did nothing. I left the fuel door solenoid disconnected & now the light flash signal works both on arm & disarm. W/fuel door solenoid connected only get light flash sequence on disarm, but still no locking or unlocking of any doors or hatch.

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    ProfessorG, March 02, 2014, 17:29
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    With the 0.2 volts still tells me a ground issue. At the manual toggle is it sending 12v or 0.2. The back solenoid May be bad. Fuel door disconnected with more working still leads me to a ground, feed back situation. It's sometimes easier when I'm looking at the results of the test as it's happening. Long story short, if there is or not battery voltage sent from the switch or at the switch and not at the actuator and the ground is attached to the battery ground. If it's not at the actuator the resistance test should give the answer. I have used the power probe so much for the last several years it's hard to test properly with anything else. It hooks straight to the battery and there is no question to the voltage or ground drop.

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    charlie320, March 02, 2014, 20:29
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    ran the power lead directly from battery to fuel door actuator & got nothing. where should I check for ground connection? Could one bad actuator cause all to fail due to bad signal to AAM? 3/10/2014-- update believe it or not all lock actuators were bad; luckily I hadn't yet sold my wrecked car! all lock/unlock @ both key fob & console button.

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