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Thread: How to tell if ECU is in limp-mode?

  1. #1
    The Aberrational Chief Engine Builder Andrew162's Avatar
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    Question How to tell if ECU is in limp-mode?

    Ok so I'm trying to adjust the timing on teh 162 after it's been pinging during several short trips today. As I understand it, the ECU has to be in limp-mode in order to correctly adjust the timing. In the DIAGNOSIS port, terminals T and E1 have to be bridged... I've tried bridging these two terminals with various things from a piece of speaker wire to a bobby-pin to a paperclip. At all times, the bit of wire that's meant to be bridging the terminals is loose in both terminal gaps. I can't actually see the contacts to get a good link between the two terminals as they're coated in that electrical grease (or whatever it is)....

    Is there a way to tell for sure if the ECU is in limp-mode? I just want to find out if there's a reason why the timing seems to be slipping. I adjusted it yesterday to 10deg because of the same problem, and I look at it today and it's at ~13deg.

    Any tips appreciated.

    Cheers.
    Clicky -> THEN: 1999 RAV4/GT-Four Hybrid
    Clicky -> NOW: 1985 ST162 Celica SX (Gen III 3S-GE) - Kitted & Resprayed


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  2. #2
    Altia ER34 GTT Domestic Engineer JetspeedCamry's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    Watch for the Check Engine Light. If those two termials are bridged correctly, the CEL will either flash constantly, or flash an error code if any are stored.
    Kind Regards,
    Kurt.

    1998 ER34 ニッサン スカイラインGT- T
    RB25DET 5 Speed Manual | Blitz SE Return Flow FMIC | Greddy Profec II Spec B BC | Apexi N1 Turbo Back Exhaust

  3. #3
    The Aberrational Chief Engine Builder Andrew162's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    The ignition has to be on for the engine light to be flashing, correct? Thanks heaps..
    Clicky -> THEN: 1999 RAV4/GT-Four Hybrid
    Clicky -> NOW: 1985 ST162 Celica SX (Gen III 3S-GE) - Kitted & Resprayed


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  4. #4
    Is a Chief Engine Builder wilbo666's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    Quote Originally Posted by Andrew162
    The ignition has to be on for the engine light to be flashing, correct? Thanks heaps..
    Correct, ign on from what I remember (with the terminals bridged).

    Should be easily googleable as well tho...

    Cheers
    Wilbo

  5. #5
    Altia ER34 GTT Domestic Engineer JetspeedCamry's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    Quote Originally Posted by Andrew162
    The ignition has to be on for the engine light to be flashing, correct? Thanks heaps..
    Yep. Correct.
    Kind Regards,
    Kurt.

    1998 ER34 ニッサン スカイラインGT- T
    RB25DET 5 Speed Manual | Blitz SE Return Flow FMIC | Greddy Profec II Spec B BC | Apexi N1 Turbo Back Exhaust

  6. #6
    The Aberrational Chief Engine Builder Andrew162's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    Hmmm strange... I've tried every possible way to get these terminals bridged and I can't get the ECU warning lamp on the dash to flash (go into limp-mode).

    I wonder is there anything I'm doing wrong?
    Clicky -> THEN: 1999 RAV4/GT-Four Hybrid
    Clicky -> NOW: 1985 ST162 Celica SX (Gen III 3S-GE) - Kitted & Resprayed


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  7. #7
    Junior Member Conversion King Jorrs's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    Quote Originally Posted by JetspeedCamry
    Watch for the Check Engine Light. If those two termials are bridged correctly, the CEL will either flash constantly, or flash an error code if any are stored.
    do they, bridge the two wires ova and should flash, use a pin or somethin,

    one thing if its not workin the ECU dionistic might not actually be connected ! i found that out with my car, not actually connected so not gona spit anything out.

  8. #8
    The Aberrational Chief Engine Builder Andrew162's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    How do I find out, just trace the wires back to the source?

    Pretty obvious, but .... yeah..
    Clicky -> THEN: 1999 RAV4/GT-Four Hybrid
    Clicky -> NOW: 1985 ST162 Celica SX (Gen III 3S-GE) - Kitted & Resprayed


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  9. #9
    Junior Member Conversion King Jorrs's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    yeh trace the wires underneath it. most likely its the same thing id say, cos u should be gettin lil blimps and stuff.

  10. #10
    The Aberrational Chief Engine Builder Andrew162's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    Yeah, I'll check that stuff out later on today. Seems to be a few things wrong with the engine bay right now, which I'm trying to sort out. Well what can you expect with a 20 year old car which has a history that you know nothing of?
    Clicky -> THEN: 1999 RAV4/GT-Four Hybrid
    Clicky -> NOW: 1985 ST162 Celica SX (Gen III 3S-GE) - Kitted & Resprayed


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  11. #11
    Junior Member Conversion King Jorrs's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    lol i no exactly how u feel ! not with my GT2 but my old 162, bloody hell i spent alot of time and money on that thing, u prob did c it, but had best paint out of any 162 u seen, i had it resprayed and all. ill post up a pic now if u want.
    sum things to worry about are wiring pretty much in these older motors and all, things detirorate and people sumtimes do dumb dodgy things, i remember the 162 i had the guy before me had tried to modify the inside of the AFM but making it open up more, couldnt tell and he had rippedthe solder of a wire and come loose, 2 months of pain in arse it not starting before i replaced the AFM cos i had replaced everything else and it got it workin.




  12. #12
    The Aberrational Chief Engine Builder Andrew162's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    "Ignition Timing: 10deg with the terminal T short-sircuited at idle."

    Short-circuited to what, E1? The stick under the bonnet for valve clearances and timing specs doesn't say. It appears as though the DIAGNOSIS port is connected to the main loom through the firewall (to wherever it goes), so I'm still scratching my head on this one.
    Clicky -> THEN: 1999 RAV4/GT-Four Hybrid
    Clicky -> NOW: 1985 ST162 Celica SX (Gen III 3S-GE) - Kitted & Resprayed


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  13. #13
    Altia ER34 GTT Domestic Engineer JetspeedCamry's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    Find the T and E1 pins on the ECU connectors.
    Connect one end of a Multimeter in CONTINUITY-DIODE TEST mode to either T or E1.
    Connect the other side of the multimeter to the diagnostics port corrosponding terminal.

    If theres continuity there, then the circuit s connected. So the problem will be elsewhere.

    Repeat for the other terminal.
    Kind Regards,
    Kurt.

    1998 ER34 ニッサン スカイラインGT- T
    RB25DET 5 Speed Manual | Blitz SE Return Flow FMIC | Greddy Profec II Spec B BC | Apexi N1 Turbo Back Exhaust

  14. #14
    Oh What a Feeling! Backyard Mechanic c2888's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    does your check engine light turn on when you turn your key to on, engine not running.
    if the light works, then you wanna chase down a broken wire T or E1.
    Sometimes the pins can get pushed through the diagnostics plug, so push the wires from the other side to seat them again.

    Dan
    The spanner in my avatar is actually a 16mm, that's why it's still new

  15. #15
    The Aberrational Chief Engine Builder Andrew162's Avatar
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    Default Re: How to tell if ECU is in limp-mode?

    Check engine light does work when ignition key is turned on. I can't tell if the pins are in place or not because the contact grease is smeared in the holes (all of them) and it's not easy to tell if I can get a good contact with these terminals. Unfortunately I don't have a multimeter on me to test continuity.
    Clicky -> THEN: 1999 RAV4/GT-Four Hybrid
    Clicky -> NOW: 1985 ST162 Celica SX (Gen III 3S-GE) - Kitted & Resprayed


    TRIKKE | Video

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