Hi there

I am the owner of an 1989 XJ40 6cil Sovereign, that features the digital gauges that are so prone to failure. In fact, mine followed the same route that many other owners have been throug, .ie. initially the dashborad would intermitently refuse to work but recovered with a slight thump, and this went on a degradation path, which led to a point where the whole instrument cluster would not work at all.

I read all comments on this Forum (thanks a lot guys for the help!) and I followed the indications:
I took out the cluster, opened it, extracted the boards.
I measured voltages (DC not working)
I resoldered the main card connections and the DC power source etc

Things improved, but not completely. Now the dashboard has recovered 50%, as normally the gauges at the left of the dashboard are illuminated, but show no reading, no mileage is displayed either. However the right side (alerts etc) works well, and alerts are displayed (boot open, door open etc)

When most alerts are shown gauges remain dark, except when there is ANTI LOCK FAILURE message, then the cluster illuminates completely, fully working, and then fades again when the next message shows up. And so it goes on and off like this, I am attaching pictures taken with 2 seconds difference, they show this strange effect .

I am puzzled by this, as it proves that the dashboard is almost working, (gauges are able to work, instruments send their readings etc). Why display would go on and off intermintently is a mistery.

I am tryning now to clean the chassis grounds, as faulty ground connections are a source of electrical instability.

Has somebody had a similar experience? Any indications is welcome.

 

Hi Peeples,
I looked at this initially buy didnt comment since I have no experience with that instrument cluster. Reading through it again it sounds like since you have intermittent success "across the board" then you may be right with a poor ground. But I think theres a good possibility of a loose supply wire somewhere. For instance, I had trouble making a known good O2 sensor work until I noticed that one of the wire connectors had backed out of its housing and was not touching its mate. It might be worth having a look at the plugs on the panel for this. This is beyond my ability to check even for myself, but could there be a condenser or a voltage regulator in the cluster which is bad ?

 

Hi Jerry, thanks for your reply. What you say makes a lot of sense, if will chech the wires as maybe a loose one is the reason for this strange behaviour. I cleaned the connectors when I opened the cluster, but that may not be enough and a thourough check of cables and components is the next logical step. I drove the car yesterday, and I noticed the speed gauge did not work either which is very likely related to a loose wire as well. I will get you posted on the progress. Thanks again!