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N75 wiring

Discussion in 'A4/S4 forum(B5 Chassis)' started by NineNails, Sep 7, 2010.

  1. NineNails
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    NineNails Proud sponsor of the snack food industry

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    Hiya.
    I got 01262- Solenoid for boost pressure control (n75) 26 - 10 - output open - intermittent
    So before buying a new n75 I want to check the wiring. All wires look intact at the plug under rubber boot but can someone please tell me what voltage to expect at the plug or where the other end of the wires are so I can check for continuity? Also, does anyone know what resistance I should see across the coil of the n75?
    If I do need a new n75 is the J version a worthwhile upgrade & why?
    Cheers :thumbsup:
    Si.
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  2. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    i had this, and replaced about 6" of wire at the end of the loom and it fixed it.
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  3. evilscotsman
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    evilscotsman Space Cowboy

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    dunno the cold coil resistance mate, but it will be what it should be or it will be open circuit if buggered.

    If you get any ohms reading at all, it will be ok. A solenoid coil can be under an ohm, or can be hundreds of ohms, depends on the coil and the number of windings, pitch of the internal wire etc but its a 12v coil so you could rig up a pair of wires and power it off the battery, it should click each time power is applied and open up to blow thru, it either connects the vac line to its output pipe or it lets air in from the intake side, if its a 3 pipe job it just switches one pipe to either of the other two depending on if its on or off.

    the voltage can be up to 12v but its a pulsed signal sometimes, the other end of the wires is an ecu output.
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  4. rossbrownlee
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    rossbrownlee Ross_S4

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    you should get 25 to 35 ohms across the two terminals on the coil. outwith that and the manual recommends replacement.

    As for measuring the voltage etc, not sure what you would see, suspect 12vdc, however it is switching in and out at some frequency. I used a circuit tester (like a neon test lamp for automotive) that i borrowed from my friendly audi tech, just turned the engine on, earthed the clip of the tester and plugged the probe into the two terminals of the loom connector, one of them lit it up.

    One of the lads on the 8L chassis A3/S3 forum has done a bit of testing on the standard and uprated N75 valves and he reckoned the standard was better. not sure about your A4 but if same 1.8T engine would imagine it would be similar.
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  5. NineNails
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    NineNails Proud sponsor of the snack food industry

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    Sorted and fault code gone. It was a break in the yellow wire where it clips onto the air box top. thanks for the replies lads, very helpful but still not sure if I should uograde the n75 to the J version anyway...
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  6. evilscotsman
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    evilscotsman Space Cowboy

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    the b6 guys did a serious of tests, I think it was j7uss - look him up bud he will remember what was the better one i sure.
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