Hi all,
I know this question has been covered in various guises already, so apologies for repetition, but I have pulled my dial cluster for a service at home as (i) speedo is terribly erratic (ii) rpm gauge stops at 3000 and I have been well beyond that many times and (iii) temp gauge looks a bit low.

To my surprise the back of the cluster looks very clean, however there is some warping of the circuit board around the screws on either side of the main plug in at 3/4 o'clock and 8 o'clock (and at the edges of the cluster) and some discolouration of the printed board. Does anyone know if these issues would cause the problems I identified and if an a simple cleaning will suffice? I will test all the circuits, upgrade the green lights (which were ok actually) and re-earth the whole thing as covered elsewhere in any case, but any specific diagnosis most welcome!

Thanks!

 

Hello all,

I found most of the information I was looking for and refashioned a new ground for the speed and will ground the entire cluster against the bolt under dash.


A couple of queries=>
1. LH indicator light doesn't activate, nor do hazards lights, I believe I have installed the polarity of the LEDs correctly as I have tested in situ and also the RHD side indicator works fine
2. Does anyone know how to test the LHD indicator or nacho on the bench ( read that the "trigger is ground" on the attached very helpful schematic but I dont know what that means). I noticed that the circuit board is quite deteriorated in the lower left section.

 

Hi Matts 73

Not wishing to be disrespectful but those Contacts on your Binnacle, could do with a bit more Cleaning, to insure a Good Contact so that everything Works as it should and that includes the Contacts on the Plugs as well as the Sockets

Lemon Juice on a Cotton Bud or just using the Rubber on the end of a Pencil usually works, or maybe even a Combination of both

From a personal viewpoint, I would avoid using LED's which can prove more trouble than they're worth

But since you've now got the Binnacle out (which for anyone else reading this is a fairly simple job)

Why not go the whole 'Nine Yards' and upgrade the Bulbs in the Binnacle to Brighter 5 Watt Bulbs, which makes a massive difference and is a real game changer on those night drives, where before you could hardly see the Speedo

Have a look at my 'Step by Step Guide' including all the Photo you may need to do this job, within a little much the same on any XJS

'Greg' even went further and also removed the Green Filters, which involves a bit of extra dismantling but I was not that Brave! as if you have a problem undoing those extra Screws, then you may start wishing that you had left those Green Filters well alone

Just replacing the Binnacle Bulbs with Brighter 5 Watt Bulbs, is as far as I would ever want or need to go

Upgrading the Lights in the Binnacle of your XJS to Brighter 5 Watt Bulbs

 

Thank you orange blossom, I will give them another clean then appreciate the input and your guide which is super.

I already changed the back lights to 5W it makes a huge difference and I also independently earthed my tacho (to the bar at the top) which now (finally) spins beyond 3000rpm. My speedo is still a little erratic so I need to work on earthing that properly I think. My coolant temp gauge barely moves from cold so there may also be an earthing issue there, I don't think there is any harm in wiring that GND up to the bar at the top either?

Unfortunately I seem to have lost LHD indicator and Hazard warning lights during this process, I am unclear as to what has gone wrong there I used both the original lamps and LEDs so it's not a polarity issue. Perhaps it is a dirty connector as you say, but happy to hear otherwise.

In general the printed circuit board deteriorated rapidly whilst in the dry warm air of my home so I have had to do a little patching up...

 

The speedo can be treated like the tachometer in that they both need power, ground, and signal.

Redundant grounds can only help, never hurt, in this scenario.

Operation of dashboard indicators for the turn signals might be confounded by the diodes....which are a bit further down in the harness. But it may be a bit premature to go there at the moment.

The individual indicator for the hazard lights is operated from the hazard switch itself. In fact, the turn signal circuit originates at the hazard switch. The contacts in the hazard switch can oxidize, causing anomalies. Often just briskly and repeatedly operating the hazard switch clears the oxidation and cures some mystery faults

Cheers
DD

 

Thank you Doug, I'll revisit the speedo inputs and earth/GND.

On the indicator lights: I should have been more clear- the lights all worked fine before I pulled the cluster. Now that I have done it they all work other than only the LH indicator and Hazards (so far as I know of course- no idea how to test the low fuel light and low coolant light...!)...

Thanks
Matt