Ebay truck acting up

[Randee of the Redwoods]

After 2.5 hours in the snow last winter testing batteries at the local auto parts store, my bettery light has started flickering again. One battery had been replaced then and the other tested good and was quick charged or whatever that machine does. The bettery light flickered all the way up to Alexandria and back. Also, ses light flickered several times. Pulled codes while fueling up. The dreaded "slipping transmission component" code came up again. It had been gone since the last time I brought it up, but has resurfaced. Driving the truck has shown me maybe it's gears 2 and 3 that are having the problems. Truck still drives great but is still lethargic as all get out. I'm wondering if the worn out tranny may have something to do with it. I was planning on having it rebuilt even before I bought the truck, but the hg thing got in the way. 185k on the ticker, gooseneck adapter in the bed, stored codes for slipping transmission. I sense a connection. I also sense a great burden to my Mastercard. I hope the tranny will hold out long enough for me to get it fixed, maybe this summer. Starting to wonder if I should have taken the Ebay chance to begin with now.

[HowieE]

Before you tear into the trans lets make sure everything is good on the battery side. You said you tested the batteries but made no mention of testing the alternator. If you are having trouble with low voltage that may be effecting other things. How are your headlights when you get the battery light?
If the charging circuit and batteries check out OK you can check the trans for slippage by putting it in 3rd or 4th and running it up to 55+ mph. While at a steady 55 mph, perferably on a grade, the convertor should be locked. While watching the Tack tap the accelerator just enough to call for power. If you see a jump of 100 -200 rpm in the Tack either the convertor or the clutch is slipping. If you see a large jump in the Tack you have most likely pushed to hard on the accelerator and unlocked the convertor.
I hope it is simple and you did not get a bad deal through E Bay.

[Randee of the Redwoods]

I've been thinking about the alternater for some time, but the flickering is so infrequent, I think it would pass a bench test. I'm going to replace the other battery first since the flickering battery light and dipping voltmeter gauge act exactly like when I found the first bad battery. I want to think the other battery may be bad as well, maybe it just so happened to check ok that day. Also, this problem has only restarted since the outside temps dropped back into the 40's and below. Seems a bit odd that everything was fine when warm. So, if that does not work, I'll replace the alternater. I've checked the wiring digrams and the charging circuit does not in any way go through the computer so that rules out some sort of outside interference. And with that, no code to direct me to a particular area to check. I'll be replacing the belt as well. I do not know it's service life and it will rule out any slippage due to stretch.

[Gapper_ca]

Well when i got my truck i had one battery that was testing bad. then other was good???
i changed both out at the same time, cousin has been runing diesel's since the first 6.2l came out. he has said that all he gets is 3 yrs out of a set of battery's and that you must change both at the same time. his trucks have always started no matter how cold it was out.
hope you get the tranny issue solved soon tho.

[Turbine Doc]

Randee,
GM's ground loop is notoriously bad, in addition to alternator check out try a dedicated ground from back of alternator mount to the truck frame using a double ring lug battery cable say maybe 4 gauge.

My 90 gasser had similar problems I thought it was related to the underdrive pulleys I had added, while working on my CB radio I saw my under hood light get brighter when connecting the radio to the battery.

Sleuthing down the phenomena, I found the main ground lead on back of engine by the starter was broken, the new cable at the alternator cured my charging problems, plus the connection is out in the open where I can monitor it now.

[gvig]

Randee,

The advice about changing both batteries at the same time is right on the mark. I drove an 84 Sub with 6.2 for about 280K and now with my high mileage 6.5 I always change both batteries at the same time. I also agree that after three years, change them whether or they need it or not. That way you don't become a pedestrian. Driving is so much more fun than walking.

[Randee of the Redwoods]

Ok, then. I'll sink the bucks for a new battery. Kind of a shame if it turns out to be good. I'll be in the area of the store when I had the battery changed out last winter so I can at least guarentee a matching battery. Advance Titanium 950amp, 770cca.
As for the connections, I'll check them again, but the seem ok. I changed all battery cables but one right after I bought the truck. It was a mess. I put in all 2 gauge cables. Real pain, but the heavy gauge stuff really halps the starter. I do know some of the connections aren't perfect, but they are beyond acceptable so I'll go in a refine them a bit to be sure. I also replaced that sheezy charge lead from the alt to the left batt with a homemade, high quality lead of 8 gauge high copper stereo amp power wire and gold plated lugs. It even looks stronger than the weenie piece that was original. I know you're mad at me for cutting out that fusable link, but I did.
I've had the cable to do the last starter lead, just haven't done it. I do that soon, change out that other battery and see what happens. If it turns out the alt is really the cause of hte problem, someone here owes me $70 for a battery I didn't have to change out. :D

[whatnot]

That is the reason I buy Walmart batteries. They don't test them around here so you can always get a new set if one goes bad.

[Polar Diesel]

Do the bad grounds appy to 93's as well? Ever since i've had my truck, the lights flicker with the engine running. the volt gauge, radio, underhood light. replaced alts. twice no luck. new batts. has to be a ground some place. any ideas?

[Randee of the Redwoods]

Couldn't tell you, Polar. Sorry. The principle may be the same since the charging system is independant of the computer on my truck, so it will closely match yours. Best bet is to check them all especially the lead going to the starter. When my truck was delivered, I found this one to be the worst of them all.
-OK-new battery is in, but temps are in the 70's here now. It will take temps back in the 40's to expose this nagging trouble again so it looks like I'm out of it until next winter. I'll focus on the transmission now.