Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing GDI Gauges Intermittent Fault

Mark, is there any evidence of it getting damp in that location in the past, as it could creep into the crimped connections grow a bit of corrosion unseen and cause hi resistance in the splices ?

Mark, back to your original post and just another thought perhaps to consider....

There is another reason why a CAN may temporarily drop out as yours did other than a suspected faulty connection. Another possible reason is from radiated electrical noise or spikes. Noise can disrupt the comms causing data loss and symptoms like you experienced. Those twisted pair network wires will only offers partial protection to interference, in an ideal world they would be fully screened. By any chance have you done any electrical mods to your car lately? Run any power cables near to the CAN wires? That pair of joined red and black wires in your last pic, are they original? I have a dim recollection from another post that at one point you were experimenting with drawing air out of the cabin through the heater matrix with a cheapy electric fan?

Hi Jon, no sign of damp at all, looks clean. At some point I may have to revisit the splices, but will probably pay for them to be redone professionally.

I have fitted the extractor fans but that was well after this issue started.

Have been back through my notes and apart from a new battery, just prior to the trip, the only electrical mod was Cruise control fitted in Feb 2022 a good 18 months prior to the 1st time we noticed it. There is chance we simply missed previous events, but I can confirm that the issue occurs with cruise control off or on.

Staying with interference as a possible cause, one of my 1st mods was to replace the radio with a Bluetooth amplifier attached under the dash which is almost always on attached to my phone so I can hear GPS instructions.

Is there any simple way to shield either the CAN wiring or Cruise Control unit from each other.

Regards

Does the cruise control use CANBUS derived speed or its own GPS module Mark?

Try pulling the fuse to the Cruise to kill it's supply & go for a test run watching the Gauges ?

IIRC Mark's had his CC for 3 or 4 years now, without previous problems

Hi Richard, the cruise control connects to the VSS on the front offside wheel.

Hi Jon, will add this to the list of tests. The issue is that a "Run" has to be a day out with stops and occasionally the dials behave themselves. Most annoying!

Wow, I'm impressed that you keep notes Mark


Not really, I don't think that it would be that easy or practical.

However having said that, I have used adhesive copper tape for RF shielding before. Maybe one of the vulnerable area's of the loom might be the first few inches of wiring exiting the chassis/engine connector, including the splices. It looks to be a bit of a birds nest and would hazard a guess that the twisting of the CAN wires is not great there. You could possibly get access to wrap the bundle in copper tape. That might help to protect from noise outside of the loom and from those near power wires, that I think you may have introduced? It's something perhaps you could try for a while and rip it off again if not needed, with no harm done.

Don't forget to ground the copper tape though!

Yes the wiring schematic implies CANBUS lines (high and low) are twisted pairs for both high and medium speed, the latter to/from BCU. Ditto the immersed fuel pump supply cables from what MMC call the "electronic fuel pump relay" which suggests the latter may use PCM to control motor speed. On the Roadster a screened cable is used instead for this feed, with screen braid grounded independent of motor ground, suggesting this may have caused issues prior.