1. #1
    JeepJerk's Avatar
    JeepJerk is offline Junior Member
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    98 TJ #1 Injector Problem

    I'm getting code P0201, Injector Circuit Malfunction-Cylinder 1. Noid light flashes but it seems dim to me (same on all cylinders). Swapped #1 and #2 injectors, cleared the code and drove it, P0201 again. What could be going on? The ECU was recently replaced. What should I test now?

  2. #2
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    k-2
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    Re: 98 TJ #1 Injector Problem

    I am guessing a 4.0L.
    Code is specific - problem with circuit 1inj - WIRING - inj to PCM is open or shorted.
    check connector #1 - the connector available separate from harness.
    Could be intermittent tug and pull on harness when checking continuity - Check haness at rear f head for chaffing.

    Why was ECU replaced?

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    Re: 98 TJ #1 Injector Problem

    Yes, 4.0. I just bought it, the previous owner bought it not running from someone else and put the ECU in as part of the work he was doing to it. He replaced injector #1 and it looks a little different from the rest of the Siemens Deka injectors which is why I swapped #2 with #1 to see if the computer would throw a P0202 code but it's still throwing P0201. I agree, next would be to check the harness more thoroughly (I have given it a pretty close look already) and maybe replace the connector. Any other ideas would be much appreciated, I'm starting to get a little frustrated!

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    Re: 98 TJ #1 Injector Problem

    you swapped inj so unlikely an inj.
    Connector would be next suspect -
    Check harness at back of head where it turns down - seen them rub thru on head bolt.
    Can you use a DVOM and wiring dia? To ohm wire to PCM.?

    I suspect intermittent so wiggle tug harness when testing

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    Re: 98 TJ #1 Injector Problem

    go to your local auto supply source and get a can of trailer connector spray cleaner, its a red liquid anti oxident. use it on all the associated connections liberally and if you have a brush use that in addition and spray again. more often than not corrosion on the connector first, damaged harness second. (this connector cleaner spray is in my go to list since it is so useful, for ALL ekectrical connections from lights topcm connectors)

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    JeepJerk's Avatar
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    Re: 98 TJ #1 Injector Problem

    It was the connector...got one from the junkyard and everything works like it should. Thanks!

  7. #7
    k-2's Avatar
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    Re: 98 TJ #1 Injector Problem

    Glad you got it solved - FYI or anyone reading injector* connectors are sold separate from harness at part stores inexpensive.

    *other wire connectors available

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