Improving the Instrument Panel Ground

 

The ground point for the complete instrument cluster on your XJ or MJ is located up under the driver’s side dash. If you lay on your back and look up under there with a flashlight, without wearing a hat, you will see a black wire attached to a shiny piece of metal almost directly above the hood release knob. The screw will have either a ¼” or 5/16″ head on it.

This ground point is responsible for handling the ground circuit for the following items: Dome lamps, seat belt and key warnings, transmission power/comfort switch, wiper switch, headlamp switch and delay module, fog lamp switch, cargo lamp switch, all instrument panel grounds and illumination, power windows and door locks, cruise control dump valve, and a few more things.

The problem is that where the ground point is located does not share good contact with the chassis where the ground should be. The solution is simple:

  • Make up a jumper wire with #10 gauge wire about 10″ long. On one end, crimp on a ¼” round wire terminal. On the other end, crimp on a 3/8″ round wire terminal.
  • Remove the screw from the existing ground wire and attach the small terminal of your jumper so that the original wire and your new jumper share the same attaching point, one over the other.
  • Look above the driver’s side plastic kick panel just forward of the top of the hood release knob. You will see an 8mm stud there. Attach the large terminal end there with a washer and nut over it tightened securely. Use a coating of OxGard at all ground contact surfaces when attaching the screw and nut.

IP ground location

**Special note for Comanche owners: Make your jumper wire 12″ long and attach it on the driver’s side kick panel close to the fusebox on the 8mm stud.**

10 thoughts on “Improving the Instrument Panel Ground”

  1. 1990 XJ removed the aforementioned ground wire in hopes this was issue with my weak power locks, once removed, they still worked weakly, power windows still operated fine, dome lights still workec. This ground wire evidently is not the ground for these items

  2. Hello Cruiser. I found my way here from the NAXJA forum. I have a stock 1993 XJ 4.0 (so not a Renix…) and am trying to solve an electrical problem or two. The hazard flasher lights don’t work, although the turn-indicators do. All the bulbs are good, and I’ve checked and cleaned all the bulb-fittings.

    I have tried two – new – replacements for the hazard-flasher unit (it was a Wagner 224). One is thermal, the other electro-mechanical. Neither works. Initially they made the hazards flash sporadically, now the hazards simply don’t flash at all.

    I’m thinking it may be a bad ground connection (which is how I arrived on your site!). But exactly which ground connections should I check – there are more than just the one by the fusebox/kick panel.

    Another problem which may or may not be relevant: the dash instruments all work fine, except that the speedo needle has a mind of its own. Sometimes doesn’t move at all, sometimes wakes up after 15 minutes driving, often reads 30mph too high, sometimes revolves clockwise back to zero. Is this another sign of a bad ground somewhere?

    1. Find every ground in your engine bay and refresh it.

      Do you have a trailer harness?

      You aware of the taillight and fuel pump ground behind the panel that’s behind the spare tire, right?

      1. Ok, will do – assuming I can find all those ground connections in the engine bay!
        I don’t have a trailer harness, by the way…
        I’ll try to find that tail-light and fuel pump ground connection at the back as well.
        But the key question (surely…) is where EXACTLY is the ground connection that serves the turn/hazard circuits? It’s labelled as ground connection “I” in the XJ wiring diagrams, and is said to be on the “left side shield”. There’s also connection “J” on the “right side kick panel”. But I’m danged if I can find either of these. I need a picture or diagram with an arrow on it to show these locations.

  3. Every engine bay ground is in plain sight. Black wires with sheet metal screw going to body.

    Remove the spare tire and the panel behind it. Fuel pump and lighting ground is there. Black wire with sheet metal screw.

    Do the instrument panel ground upgrade.

    1. Thanks – have been able to see and identify all the ground connections in the engine bay, and have “refreshed” them all.

      Also found and cleaned up the one behind the spare tyre – which was in fact clean and uncorroded.

      Having hung upside down in the driver’s seat, twisted my neck through 180 degrees, banged my head on the brake pedal and fought my way through a tangle of wires, I can see (with one eye!) where the ground connection is behind and below the instrument panel. Looks as if access to clean it up – and/or to do the suggested upgrade – requires removal of the plastic panels below the dash and steering wheel. A job for another day.

      Meanwhile, mystery solved with the turn/hazard flasher units. I thought the turn flasher relay was faulty, and the hazard one was good. Turned out to be the other way round. They seem to be interconnected (one won’t work without the other). Replaced the hazard flasher unit, and both circuits now work fine!

      Mystery over the weird behaviour of the speedo needle remains…

  4. No steering wheel removal needed.

    That instrument panel ground is important to upgrade.

    The wobbly speedo needle was provided from the factory at no extra charge….LOL. The routing wasn’t optimal for sure. You can lube the cables and hope for improvement.

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