Recently it has been behaving strangely. Started gradually where the gauge cluster would cycle on and off occasionally while driving.

at first it was contained to the cluster aka the vehicle would continue to operate normally even when the cluster shut down.

eventually it got worse and it would cycle on and off continuously even while sitting still to the point where it had become inoperable.

There was a constant clicking/cycling that I was able to narrow down to 3 relays: k4,k5 & k10 were all cycling and it appeared to do so non-stop whether there was ign power or not.

given my past experiences with automotive electronics 8/10 times the root cause is a bad ground but the all the ground lugs were wire brushed very recently(in the engine bay) and showed zero signs of corrosion.

on a act of trying randomly things my first goto was a ‘reset’ I removed the ground post terminal for 60 seconds and re-attached it.

problem disappeared(for now).

I have seen similar issues actually tied to replacing the ground post terminal and it is definitely first on my todo list bc it’s cheap and easy.

I may get lucky and that may fix it but based off the erratic behavior and the ‘reset’ fixing it I suspect however that the actual root cause is related to a module controller.

given the 3 relays clicking and the display going on and off can anyone possibly advise me as to which module sends signals to activate the display(the affected parts were the gauges and idiot lights while the green text was unaffected) and those 3 relays?

given that it ran normally without issue and the reset seemed to alleviate the issue for now im not leaning towards the ign switch.

no diagnostic codes recent or in the history.

other than trying to attack it proactively now that I have narrowed it down some however; if my initial attempts are unproductive I will simply have to wait until the problem returns and do a ground resistance check from a few various points.

also replaced the ground strap from engine to chassis somewhat recently.

if this does point to a particular module then can anyone advise me if the suspect module is vin coded or not?

my gut instinct tells me that currently the problem can be repaired aka it’s probably a module that has had contact with liquid and is a little corroded or possibly a ground wire that is nearly broken/only has a few strands left.

being that the issue is not constant I can most likely clean it or whatever ground lug it is connected to and will be okay or worst case run a dedicated ground jumper to another known good grounding point.

Can anyone with a service manual advise me where to check and what resistance range is acceptable for that point?

thanks in advance

ps it’s a 2010 tc touring with a 3.8L v6

any questions just ask.