Z32 Tacho not working 91 z32 TT

Discussion in 'Technical' started by FITZ, Feb 22, 2022.

  1. FITZ

    FITZ Member

    Helping out on a 91 TT man z32, the tacho and oil pressure have suddenly stopped. Only things weve done was remove a cd player, front bumper/lights and new steering wheel.

    Everything else works on the dash no problems...

    Any ideas?
     
  2. NI85

    NI85 Active Member

    So the boost, fuel & temp work? As they with the tacho and oil pressure, share the same dash plug. (FSM EL page 66) Maybe take the dash hood off to see if plug connection is fully clipped in.
    If the gauge cluster had been removed in the past at some point; the plug might not have been pushed all the way home and it might have decided to just come loose with vibration from pulling the steering wheel.
     
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  3. FITZ

    FITZ Member

    Yes everything else works, ill recheck the plug again but it seemed ok. There is a total of 3 main plugs in the back of the cluster? Does 1 plug give signal to all gauges?
    There isnt a seperate fuse or relay ?
     
  4. NI85

    NI85 Active Member

    They all share the same power and ground, just signal wires go their own way. Oil (Y/W wire) and Tacho (Y/R wire) signal wires are above and below each other on the one plug (Tacho side of gauge cluster)
     
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  5. FITZ

    FITZ Member

    Thanks alot, ill recheck when i can and update. Hopefully we over looked a loose plug or pin. Being there both on the same plug and neither are working it sounds like a easy fix?
     
  6. MickW

    MickW Carntry member...

    NI85 is on it, go back over what you recently did.

    Every time I push a multi pin plug into place I check the back of the plug.
    Sometimes need a mirror and torch.
    Make sure the metal connectors are all at the same relative height to each other.
    If one is higher than the others, there's your most likely culprit.
    It's rare to see that on these cars because the connectors were top quality but hey, 30 + years old connectors...
     
  7. FITZ

    FITZ Member

    No luck, rechecked plug / pins are all pressed in. Speedo, temp, fuel all work. Just tacho and oil pressure.

    Is there anything else to check or time to pull cluster out and go over the other 2 plugs?
     
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  8. FITZ

    FITZ Member

    Update, boost is not working either. Gauge has power as it jumps when ignition is turned on but doesnt move while boosting etc.

    So now no tacho , oil pressure and boost.
     
  9. NI85

    NI85 Active Member

    Pull the cluster out.
    Check the circuit board on the cluster for damage. If OK, You might have a pinched/partly broken wire going to the cluster,
    However you need to go to page EL 67-69 of the FSM and do it's diagnosis step for the gauge cluster to find what is actually working and not.
     
  10. FITZ

    FITZ Member

    Will do, I have access to another cluster so ill try this aswell.
     
  11. FITZ

    FITZ Member

    Are all TT clusters the same ? no issues from 2+2 to 2+0 etc
     
  12. NI85

    NI85 Active Member

    I know late model clusters have a plug change, cant remember what specifically. But the gauges themselves can swap out; as that is what I did with one of them.
     
  13. FITZ

    FITZ Member

    Cluster removed, cannot see any real damage or pinched wiring. Plugs are in good shape. Was very hard to release them.
    Boost gauge does jump around on start up. So no worries there now. Back to the oil pressure and tacho only not working.

    Note.. There is a tiny scratch? on circuit would this cause any issues?

    Pics attached

    20220226_115946.jpg 20220226_142858.jpg 20220226_115926.jpg
     
  14. MickW

    MickW Carntry member...

    Just thinking out loud here but did you mess with any ground connectors while you did those works?
    I can't imagine how the front light circuits would upset the instruments but hey, Z32.

    Hang on. Have you checked ALL of the fuses? No joke, it was sometimes a fuse on a different circuit that would somehow disable a seemingly unrelated system. Tedious job but easy to check.

    PS, nice pics of the cluster circuit board mate, thanks :)
     
  15. FITZ

    FITZ Member

    We dont think so, the earthing for the cluster looks like it goes back into the body loom rather than seperate. I havent checked all the fuses which i will now. Its realy strange...
    I will test with another cluster when i can, if no good, ill get my hands on a multi meter and start testing the signal wires?
     
  16. NI85

    NI85 Active Member

    When the gauge cluster was plugged in and engine running, did you wiggle the wires to the plug to see if the gauges jumped back to life?
    ---
    Are the screws to the gauges themselves done up snug?
    ---
    Side note: I had issue with my Driver side door light switch. It measured 12V, but it couldn't supply the current to the light. In its case, it was the diode pack. Its little squiggle circuit line was partially burned out. (thankfully it's a cluster of 5 diodes so re pinned to good one)
    So when you test for Voltage, it may show, but the power wire might have a few strands broken, so all the gauges can't work properly.
     
  17. FITZ

    FITZ Member

    All cabin fuses checked no problems, wiggled wiring plug and wires while running. No luck. Screws appear snug but il check this.

    The 1 plug has the signal / power and ground for the tacho and oil pressure gauge ?
    From cluster do these go back to the ecu ?
     
  18. NI85

    NI85 Active Member

    Whilst the oil signal goes to the pressure sender unit, and the Tacho goes to ECU, the cluster you shown is the later model. My FSM is for the earlier style. The connections for tacho and oil on your one, is the top horizontal 12pin plug.
    http://www.xenonzcar.com/z32/fsm.php has the later FSM downloads. As I downloaded the one in the this site's tech section and it's for the early one.
     
  19. FITZ

    FITZ Member

    Later model? His cars a 1991? Thanks, so the plug in question will now be the left side top (speedo side).
     
  20. FITZ

    FITZ Member

    If im reading this correctly, tacho and oil is still on the right side , single vertical plug? (see attachment) Pin 23 Tacho and 32 Oil .

    Interesting that fuel, hi beam, turn lh rh all work on this plug ? Screenshot_20220228-064854_Drive.jpg
     

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