[brad s1]

I fit a new alt and battery a couple of months ago, even on initial start up it was only putting out 13.8-14.0 admittedly hasn't ever been an issue. I remember these cars showing more at idle yes? In the mid 14 range? Anyway a couple of days ago (no error message) came off a red light normal/slow and it went to 4500 rpm before shifting. I got off it, it lumbered into gear then no issues. Chalked it up to a rover glitch and moved on. I'm driving this morning and the radio begins buzzing with strange digital sounding interference as I'm pulling up to a store. Return to the car, turn it on, xmas tree scrolling errors + suspension lowered message despite the suspension staying standard. Restart and everything is cleared. Get home and the battery tests 12.79 car on 13.8-9. Watching the meter lights on, stereo blasting, all heated seats the alternator is still putting that same 13.8v across the battery so I'm assuming that's just what this particular alternators voltage regulator is dialed in to do. Having owned these cars forever usually behavior like this is followed by some complete failure, any ideas guys?

In the meantime I've pulled codes (too many faults to narrow it down so seems electrical) I'm going to check earth and power connections later then reboot the car... Hopefully it's just some small software glitch a reboot will remedy but I'm not so sure.

 

[brad s1]

Checked everything and all looked good except the positive terminal. When I put the 13mm spanner over the nut to remove it, as soon as I put any pressure to break the nut the whole terminal spun on the lead, seemed like it had somehow worked itself a little loose. I reset the car, cleaned the leads and refit. Everything is tight now, will report back if the issue reoccurs. I've had similar happen before and the problem was the neg terminal had some something similar, so I"m hopeful this was the whole problem.

 

[DCartisan]

Sounds interesting... keep us updated.

Sent from my SM-G930T using Tapatalk

 

[brad s1]

Yep, no joy... That'd have been too easy a fix. Seems once in every 3 or 4 times I start the car it xmas trees. Restart and it's fine. The alt and battery are basically new so tough to blame those but you never know. Strange problem, I'm going to look at the error codes closely later.

 

[diff]

I had the same issue with the negative terminal and tightening may not be enough so I had to file something on the cable to make it go a touch tighter. If that truly is not it it sure seems like the alt. is not putting out quite enough juice. Can really only offer moral support so keep us posted.

 

[brad s1]

I had the same issue with the negative terminal and tightening may not be enough so I had to file something on the cable to make it go a touch tighter. If that truly is not it it sure seems like the alt. is not putting out quite enough juice. Can really only offer moral support so keep us posted.

Thanks for the post, everything is tight now, still an issue. The number of codes it has to be electrical (everything triggers simultaneously xmas tree, even the adaptive headlights go into error) tho if it were the alternator you'd imagine during a long drive with everything in the car running you'd get an error or at least post shut down the battery would be weakened... I drove for 2 hours yesterday and put a meter on the battery 12.78V at shut down. I noticed if I get into the car and immediately turn the car on everything faults. If I first put it to accessories letting all the computers establish, then fire the engine no issues whatsoever. I'm going to shotgun the issue with a new battery despite the fact it tests well and it is relatively new. I'm thinking maybe it's defective in regard to the amp delivery as when you immediately fire the engine the amps are insufficient, volts drop and everything triggers. First putting it to accessories, charging up all the electronics and then starting seems to work around the issue. Who knows though, it could be any number of things. Will keep you guys posted.

 

[RABarrett]

You might try tracing all of the grounds, battery, chassis and body grounds. Bad connections can cause higher than normal voltages at these locations, confusing the logic circuits. The easiest way would be to use a DVM, checking the voltages between battery negative, chassis ground,and the body grounds. I would think that any voltage exceeding .5 volts to be excessive. Ray