98 Disco 160k
She has had all kinds of issues lately which I finally tracked down to the larger black wiring harness connector going to the ECU. When I wiggle it, the idle goes all over the place. Has anyone else had this issue, and what steps did you take to remedy it?

 

The ECU monitors lots of sensors, supplies voltage to them to operate, and supplies grounds at precise times to injectors and spark coils to operate them. So wiggle could be lots of things. With main battery disconnected, you can remove the ECU plug, and use spray contact cleaner (made for electrical contacts, not MAF cleaner, not carb cleaner, no oven cleaner) for both the plug and socket. Inspect pins for bent pin (unusual). Inspect for gunk (green slime, etc.). There is a dielectric spray or gel that can be placed on the pins. Dielectric keep out moisture, and is an insulator. Whoa, you may think it would insulate pins from plug, but what happens is that electrical plugs only touch on a few small points, the rest is air space between the contacts on a microscopic level. The dielectric fills what would be an air space anyway, and prevents corrossion from building up. The metal points still slice through the dielectric grease and make metal to metal contact. Some guys weather proof the ECU to keep splashed water from frog stranglers (heavy rain) or small creeks from soaking the ECU.

 

If you look at the TSB and Recalls Flag at the top of the page you will see a huge list of items that you should scan thru just to be aware of past issues.

One that I specifically remember is individual contacts working their way loose in the connector housing and loosing the intimate connection needed for electrical connections.