cwm921

Bought a used '93 GS300 3.0L w/167,000 mi. Main issue I have is battery voltage when @ idle. Battery in car @ time of purchase had 10.1V. Bought new battery & installed. Now has 12.4V. Upon start up battery reads 14.5-14.4V. I noticed dome lights dimming and then getting bright again about every 20 sec or so. Very slight difference in brightness though, but you could tell. I then checked battery @ top posts and it said 12.3V, still @ idle. Hmmmmm. OK, maybe alternator is issue? Being this will be my daily driver I opted for reman. alternator and installed. Snug fit. Started up and checked battery. DVM reads 14.4V. I let sit for about 5 min. Kept eye on DVM, turned on lights, radio, and blower fan to high. Re-checked DVW..............reads 12.2V. Does the GS300 switch charging ckt. on/off? Is there a voltage reg. aside from the alternator? What to do????????

patrickgs3

there is a voltage regulator. mine is having electrical trouble too but i have been too lazy to diagnose.

I did a search on this subject about a month ago and there are some pretty indepth threads so you might wanna search it out.

check your neg. batt. cable for corrosion. i hear that is a pretty hot topic.

cwm921

Problem solved - New alternator seems to working ok. Current draw is most with brights on. Batt. voltage goes from 14.4 to 12.8V with brights and back to 14.2 w/brights off. No other acc. bumps the voltage @ batt. Old alt. had caked-on oil from distr. oil leak just above it's location. No more dome light flicker. Need to fix ASAP.

BobbyinAtl

I have had similar battery problems with my previous 1997 SC 400 and in my current 1999 SC 400. The problem is most likely not with your battery or the alternator.

I have found by replacing the factory cable connectors to the battery with Marine type LEAD connectors that are painted, except for the areas in contact with the battery post and cables will correct the problem!

I discovered after numerous dead battery situations in both cars that the alternator was putting out the required 14.2 V (the nominal value), but the battery was not charging. Therefore the only problem could be that the charge was not getting to the battery. I replaced the connectors with new factory connectors that were flimsy aluminum. This did not solve the problem.

I finally got a good conduction current into the battery after replacing the battery connectors with plain old lead type connectors that can be purchased at any pep boys for less than five bucks.

I have since utilized the Marine connectors in my 1999 SC 400, because they are painted on any surface other than connection to the cables and the battery terminal to prevent shorts.

Hopefully this will help correct your problem as well.

PS: my brother who is a certified mechanic actually uses spray paint or grease on the battery post after tightening the connection in order to prevent oxidation of the connection.

cwm921

OK Great tip. Thx.