Stabsthedrama

89 Renix 4.0 - lights/dash lights/ac vents are dimming every 5 seconds or so when at idle. Started happening somewhat recently. Stops happening once rpm's go up, comes back at idle.

- Battery is almost brand new

- Cables are brand new

- Main grounds were refreshed and should be good, though I suppose I can do them again to check

- Extra ground strap run under dash for the instrument cluster ground

- Cap/rotor/plugs/wires brand new

- Voltage checks out fine on battery with jeep off (~12.5) - and with it running at idle, (even with all accessories on) - reads about 14.5v, so it seems fine

- Taking the battery off while the jeep is idling turned the jeep off almost instantly, twice in a row - I had done this test months back when the old battery was going, and it DID stay running for 5 minutes or so


I already have a new AC Delco 100a alternator ready to throw it in there, just trying to eliminate any other possibilities before I break into the jeep.

The alt doesn't seem to be making any weird noises, but I can hear it running, not sure what I should be hearing. It's also not getting real hot, but it is hot if you touch it for a few seconds, as I would suspect anything touching the engine would be.

I figure I'll throw it in there and see if that gets rid of the issue. Not liking the idea of driving the jeep around right now, almost seems like it wants to completely shut off at any second when it's idling, even though it's driving and running totally fine. I suppose it is possible that the idle is getting a bit too low - would that cause a dimming situation like this?

Stabsthedrama

Update - So for some reason I had thought this was only happening with the engine running, and not just with the battery. I must have not waited long enough to see the flicker. It still happens with just the battery on. This eliminates the alternator, whereas before it was pointing directly at the alternator. I guess I just have a spare alternator now, which isn't a bad thing. I got a good deal on it.

Wiggled the dipstick ground around a good bit (I had redone it awhile back) and it seemed to stop happening... I'm about 90% sure it was this ground. I will be re-refreshing it here tomorrow.

The ground refreshing didn't go quite as planned with that when I redid it - the original nut/bolt that goes there was just WAY too far gone with caked up crap since 89' to take apart, so I had just removed it - ran a #4 ground strap to the firewall, replacing the original smaller one, replaced the negative battery wire to it as well, and re-crimped the 2 extra wires going to it (ecu and whatever else - this is probably the problem, a half-assed crimp) and then just replaced it with a bolt and called it a day.

Going to take it apart again and get a better crimp on the wires.

Grounds...grounds....grounds

Always the grounds with this thing, it's no surprise this time I suppose.