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Thread: mystery relay

  1. #1
    Hybrid booster
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    Question mystery relay

    found this relay hanging down from the passenger side of the dash. any idea what it does? the car cranks but wont start. I confirmed no fuel pressure with a gauge at the rail. wonder if maybe its the fuel pump relay.
    part # on the relay is 4221570




  2. #2
    Hoosier Daddy?? Turbo Mopar Staff Clay's Avatar
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    Re: mystery relay

    well if the pump isnt coming on thats from the ASD relay which should be under the hood (its part of the power module in 87 and older vehicles). A bad HEP is one reason for the ASD relay to not turn on.
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  3. #3
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    Re: mystery relay

    Forgot to mention this is an 89 lebaron, 2.5L turbo, automatic. I swapped the ASD with another car, but no idea if either of them are any good.

  4. #4
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    Re: mystery relay

    Since its a LeBaron I'm guessing you have a power antenna.

    Unplug the relay and I bet your power antenna stops working.

    Steve

  5. #5
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    Re: mystery relay

    interesting... I will try that.

  6. #6
    turbo addict JDAWG's Avatar
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    Re: mystery relay

    amplifier and power antenna relay

  7. #7
    boostaholic BIGBRUDDA's Avatar
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    Re: mystery relay

    +1 Yep the infamous "Infinity" speaker relay. Normaly it's taped up inside the console kick panel.
    Sounds like you may have a "hall effect" problem. The ign/FI module inside the distributor.
    Try a jumper wire from +post on battery to to the coil. Listen for the pump.

  8. #8
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    Re: mystery relay

    thanks for the input.... I realized last night I swaped the silver looking relays mounted on the strut tower, thinking one of those was the ASD. However I remembered from working on anothe car, ASD is one of the black relays mounted behind the SMEC unit, I think its the one closer to the front of the car. going to try swapping that first and see what happens.

  9. #9

    Re: mystery relay

    4221570 antenna and door lock relay 1984-1990 may have other applications

  10. #10
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    Re: mystery relay

    Quote Originally Posted by Clay View Post
    well if the pump isnt coming on thats from the ASD relay which should be under the hood (its part of the power module in 87 and older vehicles). A bad HEP is one reason for the ASD relay to not turn on.

    Forgive my ignorance.... what exactly is this HEP you refer to? I assume its something to do with the Hall Effect or pick up in the distributor

  11. #11
    Hybrid booster Turbo Mopar Contributor jre97's Avatar
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    Re: mystery relay

    The HEP is the plastic piece that the wires go to in the distributor. It tells the computer when the car is cranking, on what cylinder, etc.... HEP= hall effect pickup

  12. #12
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    Re: mystery relay

    well, I am 0 for 2.... swapped with a known good ASD, no fuel pump. jumped battery + to the coil and nothing that I can hear from the fuel pump. I did verify spark from the coil to the distributor cap.

    Guess my next step is pull the tank and check for power at the fuel pump. any idea which wire I need to check for power with the key on?

  13. #13
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    Re: mystery relay

    now I am really cornfused.... Does the ASD relay energize the fuel pump when power is applied or removed?

    I lowered the fuel tank and verified no power at the pump with the key on. If I remove the relay and jump across the connector I get power to the pump.
    If the pump is engergized with power removed, how do I test for that? and what controls it?

    I tried jumping battery positive to the coil, like was mentioned and nothing changed. any other ideas?

  14. #14
    two point two much fun Turbo Mopar Staff Turbodave's Avatar
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    Re: mystery relay

    The voltage to the pump, the + on the coil and a few other items are all on the same circuit, and are engergized when the ASD relay is actuated. If your getting spark then the circuit is good. There will be power to the pump, but only for a few seconds when you first try to crank it, after that it kills the power if no crank signal is seen. If you have been trying over and over again to start it you may need to disconnect the battery and re-try it. Depending upon the computer some will only let 4 or 5 attempts before it cuts off power to the ASD all together.

    Disconnect your battery, the try it again, then check your codes, code 11 is a sure-fire sign that something is up with the HEP circuit.

    If that's all good and you are getting power to the fuel pump, maybe the pump itself is bad?
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  15. #15
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    Re: mystery relay

    Quote Originally Posted by Turbodave View Post
    The voltage to the pump, the + on the coil and a few other items are all on the same circuit, and are engergized when the ASD relay is actuated. If your getting spark then the circuit is good. There will be power to the pump, but only for a few seconds when you first try to crank it, after that it kills the power if no crank signal is seen. If you have been trying over and over again to start it you may need to disconnect the battery and re-try it. Depending upon the computer some will only let 4 or 5 attempts before it cuts off power to the ASD all together.

    Disconnect your battery, the try it again, then check your codes, code 11 is a sure-fire sign that something is up with the HEP circuit.

    If that's all good and you are getting power to the fuel pump, maybe the pump itself is bad?

    yeah, I am working that angle now. I jumped power to the pump and got nothing. working on pulling the tank as we speak.

  16. #16
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    Re: mystery relay

    got the tank out and the fuel pump was bad. I am off the parts store !!!!

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