Bishop Posted October 16, 2004 Share Posted October 16, 2004 OK, I've been working on my '85 hatch for a while now (yeah it finally passed smog) and I am having some trouble with the electrical system. The voltage gauge always hovers around 9 or so, lower when the radio, wipers, and headlights are on. The problem is the alternator and battery both tested good, and the volage is constant on both sides of the fusable links. The car runs OK, and the battery never seems to lose its charge, but the headlights are kind of dim, and there is a noticable drop in wiper speed when you turn on any other accessories. So far I have tested the leads coming off the battery and they remain at 12 whenever the car is off, and stay pretty solid at 11.4 when the car is running. Same story on both sides of the fusable links. I tried replacing the battery wires, adding an additional ground to the frame from the battery, and replacing some of the ground wires in the harness, all to no avail. All the fuses are good, all the accessories work, and the car runs OK (air / fuel mixture needs adjustment), but somewhere I am leaking power :-\ Any ideas on where to go from here? Quote Link to comment Share on other sites More sharing options...
NorthWet Posted October 16, 2004 Share Posted October 16, 2004 Uummm... nominal voltage for the battery is REALLY 13.2 volts, with closer to 14-14.5 volts under charge. If you are ssiing it sag below 12, then there is a problem. Too tired to offer more constructive ideas... sorry. Pat Quote Link to comment Share on other sites More sharing options...
Bishop Posted October 22, 2004 Author Share Posted October 22, 2004 Yeah, I know that the battery voltage should be higher, but it does not seem to drop off at all. I've put about 350 miles on the car since the last post and still no sign of battery discharge. The voltage still hovers around 9 / 10 on the dash gauge, 11.5 on the multimeter at the battery. The lights are dim and the wipers slow, but the car is still running strong. I figure it's a ground that is not making good contact somewhere, but WHERE?! Anybody know of any "usuall suspects" for corroded chassis gound wires? Quote Link to comment Share on other sites More sharing options...
GLCraig Posted October 22, 2004 Share Posted October 22, 2004 Under the dash, above the fuses there is a ground wire, check to see if it's tight. Quote Link to comment Share on other sites More sharing options...
NorthWet Posted October 22, 2004 Share Posted October 22, 2004 What kind of reading do you get right off of the alternator? I can't think of anything special, and the only troubles that I have had so far have been with major wires: Power and ground back to the starter. Probably those two, the ground wire on the alt itself, and maybe the ground between the passenger head and the chassis? And don't forget the connection between the cables and the battery posts themselves. Guess I've been too lucky so far... Quote Link to comment Share on other sites More sharing options...
subiemech85 Posted October 22, 2004 Share Posted October 22, 2004 search for jumping volt guage there is a wire that feeds the ign circuit that goes bad, and is the usual suspect, my first guess have your alt tested, should be 14v+/- does the volt guage go up and down when the turnsignal is on????? Quote Link to comment Share on other sites More sharing options...
edrach Posted October 22, 2004 Share Posted October 22, 2004 You may also have lost a cell in the battery. Battery voltage should be around 12.6V or better; and certainly around 13.8V with the engine running a little above idle. If the battery voltage doesn't increase with the engine running, the alternator output may not be high enough to fully charge the battery. Quote Link to comment Share on other sites More sharing options...
NorthWet Posted October 22, 2004 Share Posted October 22, 2004 You may also have lost a cell in the battery. Battery voltage should be around 12.6V or better; and certainly around 13.8V with the engine running a little above idle. If the battery voltage doesn't increase with the engine running, the alternator output may not be high enough to fully charge the battery. I was going to say that I have had GM alternators that soft-failed, had lower than normal output voltage but no weirdness like drawing battery down. But he says alt "tested good", as did the battery... not sure what test or how an under-voltage battery can test good. :-\ But I know that I have chased problems around before deciding on the obvious (obvious for me 'cuz had 2 previous similar failures ). Quote Link to comment Share on other sites More sharing options...
Bishop Posted October 22, 2004 Author Share Posted October 22, 2004 I was going to say that I have had GM alternators that soft-failed, had lower than normal output voltage but no weirdness like drawing battery down. But he says alt "tested good", as did the battery... not sure what test or how an under-voltage battery can test good. :-\ But I know that I have chased problems around before deciding on the obvious (obvious for me 'cuz had 2 previous similar failures ). Had the battery and alt tested seperately at the local parts store. They told me they were "good" on both occasions but I'm not sure about the exact results. Given the age of the car, and the ammount of general rust and corrosion elsewhere, I am assuming there are some ground wires that are not getting good contact. I will look into the ones mentioned in the above posts and let you know the results. Thanks for all the posts, they give me someplace to start! Quote Link to comment Share on other sites More sharing options...
Turbone Posted October 22, 2004 Share Posted October 22, 2004 Clean all the grounds, engine bay and under the dash. Quote Link to comment Share on other sites More sharing options...
Bishop Posted October 22, 2004 Author Share Posted October 22, 2004 search for jumping volt guage there is a wire that feeds the ign circuit that goes bad, and is the usual suspect, my first guess have your alt tested, should be 14v+/- does the volt guage go up and down when the turnsignal is on????? The volt gauge does indeed jump when the turn signal is on. Where is this wire that feeds the ignition circuit? Quote Link to comment Share on other sites More sharing options...
edrach Posted October 22, 2004 Share Posted October 22, 2004 When you test the battery voltage at the battery terminals and find the battery voltage is 12V then ground terminals have nothing to do with it other than perhaps the alternator is not getting the charge to the battery. I don't know how a shop can tell you the battery is fine when the voltage is as low as it is; it is either not completely charged or defective. Had the battery and alt tested seperately at the local parts store. They told me they were "good" on both occasions but I'm not sure about the exact results. Given the age of the car, and the ammount of general rust and corrosion elsewhere, I am assuming there are some ground wires that are not getting good contact. I will look into the ones mentioned in the above posts and let you know the results. Thanks for all the posts, they give me someplace to start! Quote Link to comment Share on other sites More sharing options...
Turbone Posted October 22, 2004 Share Posted October 22, 2004 I guess I need to slow my reading down You said you put a meter on the battery and it had only 11.5v. You need to put the meter on the alternator and find out what the output is from it. This will tell you if the alt is charging the battery with the correct voltage. As stated before, it should be in the 13/14v range. It sounds like the battery is carrying most of the load and when you turn on accessories it cant supply enough power to them. Dont always trust the parts stores when they test your stuff, take it to another shop. Maybe a alt rebuilder. Quote Link to comment Share on other sites More sharing options...
rallyruss Posted October 22, 2004 Share Posted October 22, 2004 like other stated. whats the voltage at the alt. if its higher then there is a voltage drop on the wire to the battery. I rember where that car came from. that was a bit of a damp environment. may have given you some corrosion issues. edrach- there are battery testers on the market now used by some shops and many parts stores that will test a partialy charged battery. mostly good results as long as there are good connections at the battery. Quote Link to comment Share on other sites More sharing options...
Bishop Posted October 24, 2004 Author Share Posted October 24, 2004 OK, I looked around and found a REALLY corroded ground that threads into the engine wiring harness behind the drivers side headlight. I replaced the whole wire, including several small wires that feed into it, and grounded it to the same point as the small ground wire coming off the battery negative cable. Now the battery reads 14.3 steady while running, same story at the alt, and on both sides of the fusable links. I did not test while the car was off. BAD NEWS is the volt gauge is still down around 9 / 10, jumps a lot when the signal is on, wipers are slow, and the headlights are dim. I looked around pretty good and didnt find any other ground wires under the hood. I checked the one mentioned above the fuse box under the dash, and it was good. I checked out the fuse box and the wiring harness while I was at it and everything looked OK, but I didnt examine closely. Before I had the car, someone did some shade tree electrical work for a sterio system, and rewired the radiator fans. I got most of that worked out, but there are still a couple of lose wires going into the three solonoids on the firewall in the engine compartment on the passengers side. I have no idea what they do. . .any ideas about those??? What was the ignition circuit mentioned above, and how is that coorelated to the jumping volt gauge needle when the turn signal is on????? Quote Link to comment Share on other sites More sharing options...
subiemech85 Posted October 25, 2004 Share Posted October 25, 2004 http://www.ultimatesubaru.org/forum/showthread.php?t=20240&highlight=volt has an nswer, pm McBrat if you need further explination Quote Link to comment Share on other sites More sharing options...
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