Can a loose HT lead cause a warning light?

[dpbird90]

So, was driving home the other night in the Panda, and the engine management warning light came on. Temperature gauge was normal, if anything running a little colder (would very slightly fall when stationary then get back up to normal once moving), so I stopped and had a look under the bonnet. Nothing wrong, nothing hotter than it should be, all fluids were at normal level, so I slowly drove the last mile home, where I could get a proper look and had access to more toolkit. I googled the light coming on where everything was apparantly normal, all that came up was suggesting I disconnect the battery for about an hour. Only Fiat, or the previous owner, have put some form of glue over the terminals which makes it very difficult to remove the wires, although I eventually sorted it. Reconnected them an hour later and still the warning light.
With everything appearing to be normal, I decided to leave it overnight, maybe its just a combination of very cold weather and Fiat electronics. Come the morning, the light was still there, but still we couldn't find an issue. With it being morning, there was enough light to see properly, so I got the spanners out and looked further, still nothing. Last resort, I could see the HT leads and poked them a bit, and somehow this appears to have fixed it; the light has gone out. Is it possible a loose HT lead was causing it to light up in the first place, or was it just the car coming over all Italian?

[The Wookie]

Could be a lead breaking down. Best way to find out is to get a fault code reader and see what was producing the engine light ETA as it could be a sensor with loose wiring that you've just knocked as you've been prodding around the engine bay

Edited by The Wookie on Monday 15th November 11:23

[Toffer]

Yep...it was almost certainly the loose HT lead causing problems. It may pay you to replace the HT leads with some decent ones (I have used Magnecor leads and found them to be good)? Either refer to the Haynes manual and/or label the HT leads and/or remove them and replace them one at a time...to avoid connecting them incorrectly. By the way, you mention some kind of glue on the battery terminals? Once tightened, I suggest that you lightly grease the battery posts and connections to minimise corrosion.

[dpbird90]

Thanks guys, I will earn a beard and tweed jacket one day!
Yeah the glue stuff is weird, I'll get some grease when I pop out later, cheers.

[dpbird90]

Right, had the light come on again the other day, strangely after doing exactly the same thing as last time. Had been out with a friend, when we came back I turned off the engine and we sat outside her house for about an hour chatting, and when I turned the engine back on, big yellow warning light appears. Poked the HT leads, got a bit of a shock despite having gloves on, but its done the trick again, think one of them is quite loose, am currently pricing up better ones. It just seemed strange that it did it under identical circumstances. Spoke to dad, he said go to a garage to check it out, but I begrudge paying Fiat £70-odd simply to plug a laptop in and tell me whats wrong, and then god knows how much to put it right (they wanted £500 to replace a handbrake cable, £400 of which was labour charge. I bought one from a parts place and it cost me £12, dad fitted it in half an hour with a labour charge of 2 cups of tea and 4 jaffa cakes) also the nearest Fiat dealer I can find is 60 miles away. I was hoping it'd be something I can fix myself but I need to know what fault codes are being recorded, but can't really afford the machine to do it right now