Engine check & TCL Off lights

[Foggy]

Hi all, firstly wasn't sure whether I should have posted this here or in the AWD/Verada Forum, thought might get more feedback here, will move if suggested.
I have a 2004 KL Verada, I recently has some work done, replaced starter motor and rocker cover gasket. It had been sitting for about 6-7 weeks before I got this work done, as a result the battery was flat. I put it on the charger and it started so we could check the new starter motor, all was good. The next day the battery had deteriorated so I replaced it. I drove it for a few days to work and back, was going ok, did notice a very slight delay when accelerating, it just kind of took the smooth take off away, it was like it was pushing harder than it was. A day or two later the engine error light came along with 'TCL off' light, they don't come on straight away, after about 30 seconds. The motor is now running a little rough. This has been present for about 3-4 days, I've checked it each day. For the first time this morning it was slightly surging (along with the rough idle its been doing) and the battery light was going on an off, was kind of in line with the surge.
Any thoughts on what this might be? thanks in advance.

[mcs_xi]

The TCL system is highly sensitive to the health of the electrical system. Early cars had a capacitor to insulate the system as it was prone to throwing errors over time.

I would have a look at your alternator health to make sure it is working at full capacity. Perhaps it has failed or deteriorated in some way. The battery light is the alternator not working properly. The surge could well be because of the engine idling too low but also could be because the alternator isnt working properly.

[Foggy]

The TCL system is highly sensitive to the health of the electrical system. Early cars had a capacitor to insulate the system as it was prone to throwing errors over time.

I would have a look at your alternator health to make sure it is working at full capacity. Perhaps it has failed or deteriorated in some way. The battery light is the alternator not working properly. The surge could well be because of the engine idling too low but also could be because the alternator isnt working properly.

Many thanks mate, will have alternator checked.

[rumpfy]

Two checks to do:
1. With engine stopped, measure the battery voltage. Will be less than 13 volt. Then start engine and measure battery voltage with engine running. Battery voltage MUST be at least 1 volt more than with the engine stopped.

2. With engine running and headlamps OFF, listen for the engine revs. Turn headlamps on HIGH beam, and engine WILL slow down.
If either test fails, alternator is suss.

hope this helps.