Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Dash PCB-ectomy

Thanks Geof,

Our cars are actually very similar, I did have a 2006 car for a few years. Functionally the pcb appears to be are very similar with just a different form factor. They share the same two connectors and have the same pin outs as far as I can tell. On the early cars as you say the Caerbont Multi Function Unit is behind the dash whilst mine is in the engine bay under a cover next to the my ecu. This mod to remove the pcb really doesn’t affect the MFU. The MFU uses a microprocessor and CAN interface for controlling the instrumentation, that’s a future project….

So yes in principle this mod could be done on the earlier cars but the relay assembly might need to be packaged differently owing to the available space.

2006 pcb

Thanks Roger for the update and for clarifying my mini mystery as to where your dial control boxes live.
Due to lack of “behind the dash” room it seems obvious my additional relays should also live under the bonnet.
Thank you again.

Well, I’ve collected up all my little ‘back of a fag packet sketches’ and had a stab at producing some wiring pictures. I needed something a bit prettier anyway to drop in the back of my handbook for the record so here you go... Hope it make sense

But first! This is definitely not a ‘how to’. I’m just posting what I have done for the record should anybody else with gremlins in their pcb be interested. However please don’t blindly copy this as I’m certainly no electrician. I’m sure this isn’t necessarily the only or ‘best’ solution and most likely full of silly errors too.

So use with caution…



Dashboard switch assembly connections



For simplicity I haven’t shown the switch’s LED ground wiring.




Relay assembly connections


I mused over a number of possible solutions for the indicators and hazards circuit each with their own pros and cons. This is what I’ve settled on however it may be considered unnecessarily complicated as it incorporates a couple of diodes simply to work around the issue that I couldn’t find a suitable double pole matching toggle hazard switch with a LED so used a single. Others may have done it different but a of couple additional components and a little voltage drop was a small price to pay for my matching switches. I’m sure these heavy duty diodes will be super reliable but I now have spares in the tool tray just in case… The two hazard relay could have easily been combined into a single suitable double pole relay but typically what doubles are available are not really intended for the auto applications so using two regular singles seemed appropriate. It makes carrying spares and fault finding on the fly easier too. Also if I was doing it again, for simplicity I think I would skip the 9 way Molex and wire the switches directly to the relays for simplicity. I’m not a great fan of these washing machine connectors anyway







Warning light PCB interface cable


In case the colours arn't clear I used 0.5W 560Ω resistors for all the white warning light LED's and red PATS LED.

The pcb connector pinouts might be useful too. Again this is only my stab so use with caution….



Dashboard PCB





Warning light PCB



Hope it helps somebody....

Awesome work Roger.

Can't think of a better word than to echo John's, awesome work Rog

I assumed you had removed the PCB, if so does this mean the heater fan switch now directly operates the motor?

Hope you don't mind the following suggestion. I note that Spots can only be activated (correctly) with main beam but rear fog relay takes coil power from red/orange wire which is sidelight feed. I recall this is repeating MMC's loom wiring on 2006-14 cars which I always considered wrong. Ideally it should take feed from headlamp supply before dipswitch. This is how the later cars function with BCU control so possibly worth consideration given it's a simple fix.

YES!!

Great work and good to document it .... with Morgan's being long-lived the later cars are likely to outlive their electronics which are less easy to replicate than the mechanical parts ... good that future owners have a fix in the years to come when the troublesome pcbs are no longer available.

K

Good work Roger. As a matter of interest, did you manage to find what had caused the original fault on the PCB ?
Thinking that it would be either a component failure or dry joint/track continuity fault. Both should be an easy fix. However if the fault is impossible to find their in shows the problem of these type of faults.

Thanks for the tip Richard. I didn’t really give the fog light that much attention. Thought I copied how it originally worked when I had to temporarily rewire it but it has passed the mot a couple of times like this.

Yes the new 20A heater switch drives the blower motor directly so no relays to worry about.




Thanks. I agree, the more electronics I can bin the better



I haven’t actually confirmed the original fault yet Bob. However I have quickly powered the pcb up on the bench and can see that the fault it still there, the fog light is permanently on. It appears to be using a regular 2n3904 transistor as a switch/driver for the fog light relay coil and that looks like it may have failed in the on state. I’ve ordered up a few transistors (15 pence each, ouch!) and have a few diodes here just in case too. It’s low priority at the moment but would like it back working as it gives me the option to swap back. I will report back!