Squidbilly503 Posted October 16, 2018 Share Posted October 16, 2018 I’m new to this Subaru forum. But touching on this older post. I have an 84 1800 gl, and it’s not charging. Put new alternator in, new battery, all new battery cables and grounds, new fusible links. Test the fuse on the fuse block and I have battery voltage on power side of block with fuse in, test the other side of block and there is nothing. But when I remove the L plug I get voltage on the other side of the fuse. This is a real humdinger to me Link to comment Share on other sites More sharing options...
naru2 Posted October 16, 2018 Share Posted October 16, 2018 Voltage MUST be the same on both sides of the fuse at all times. Only way it can be different is if the fuse is blown or has a poor connection. Fuse and charge light bulb must be OK in order to supply initial field current and begin charging. Link to comment Share on other sites More sharing options...
naru2 Posted October 17, 2018 Share Posted October 17, 2018 You have a poor connection(high resistance) at the fuse. This resistance is so much higher than the load resistance(the field coil+charge lamp) that all the voltage is lost at the fuse w/the circuit is loaded. When you remove the plug the circuit is broken,there is no current flow and the high resistance at the fuse is of no significance.You measure full voltage. Voltage at the white/red wire at the alt. plug(or both sides of the fuse) should be 12V key on engine off w/ the plug removed,and about 3.7V plug in IIRC. I say the charge lamp never comes on even though the bulb is good. Link to comment Share on other sites More sharing options...
Squidbilly503 Posted October 18, 2018 Author Share Posted October 18, 2018 But that is the thing the charge lamp does come on. And the gauge does work it reads about 7 volts even though the batter is fully charged. Link to comment Share on other sites More sharing options...
Squidbilly503 Posted October 18, 2018 Author Share Posted October 18, 2018 I’ll take a picture of the dash with it running tomorrow morning. It is currently sitting at my shop with a charger on it. There are other dash lights that are on constantly, since this problem arose Link to comment Share on other sites More sharing options...
DaveT Posted October 18, 2018 Share Posted October 18, 2018 I am not sure about 84, but 86 and up, it's not unusual for the alternator light to not light, and some of the others to glow when the alternator output is low. Use a voltmeter, measure the volts directly on the battery, and also directly at the alternator output terminal to it's case while running. Link to comment Share on other sites More sharing options...
naru2 Posted October 18, 2018 Share Posted October 18, 2018 12 hours ago, Squidbilly503 said: But that is the thing the charge lamp does come on. And the gauge does work it reads about 7 volts even though the batter is fully charged. The dash gauges are notoriously inaccurate,but,usually not that bad. Since you already measured full battery voltage at the charge fuse,the dash gauge reading is irrelevant for charging diagnosis. You are measuring both sides of the charge fuse-correct? Full battery voltage at the charge fuse w/key on engine off shows there is an open or high resistance somewhere in the field coil circuit. No voltage on the other side at the same time means the fuse is bad. Measure the voltage at the white/red at the alt.plug.Key on engine off with the plug both in and out. The inaccurate dash gauge is likely due to a poor dash ground. Link to comment Share on other sites More sharing options...
Squidbilly503 Posted October 19, 2018 Author Share Posted October 19, 2018 DAVET ive dome that and the battery voltage is 12.6v and tested the alternator but nothing is coming out except battery voltage. Took alt to four different places and all four had same output numbers. Link to comment Share on other sites More sharing options...
Squidbilly503 Posted October 19, 2018 Author Share Posted October 19, 2018 Naru2 so with the fuse in and the plug installed on the back of the alternator there is no voltage at the fuse. Remove the plug and there is power on both sides of the fuse. I thought that it was a contact problem in the the fuse. Removed fuse and cleaned contacts. Installed a brand new fuse. Still the same outcome Link to comment Share on other sites More sharing options...
DaveT Posted October 19, 2018 Share Posted October 19, 2018 1 hour ago, Squidbilly503 said: DAVET ive dome that and the battery voltage is 12.6v and tested the alternator but nothing is coming out except battery voltage. Took alt to four different places and all four had same output numbers. I am not sure what you are saying here - You took the alternator out, and had places test it? Link to comment Share on other sites More sharing options...
naru2 Posted October 19, 2018 Share Posted October 19, 2018 5 hours ago, Squidbilly503 said: Naru2 so with the fuse in and the plug installed on the back of the alternator there is no voltage at the fuse. Remove the plug and there is power on both sides of the fuse. I thought that it was a contact problem in the the fuse. Removed fuse and cleaned contacts. Installed a brand new fuse. Still the same outcome No voltage at the fuse w/the plug in means the high resistance is between this fuse and the battery. FYI,from the charge fuse,the circuit goes thru a diode,the charge lamp,another fuse,the ignition switch and fusible link #2. I would proceed by measuring voltage at the ignition coil + w/the plug in.The same fuse powers the charge lamp. Good volts here confirms the second fuse,the ignition switch and the fusible link are OK. That leaves the lamp the diode and the instrument cluster plugs(try wiggling them) Unfortunately,access to the lamp and diode are not simple.I`d want to measure voltages there. I`d suspect a loose plug first(could explain the low reading on the dash meter-did it go bad at the same time?) Link to comment Share on other sites More sharing options...
Squidbilly503 Posted October 19, 2018 Author Share Posted October 19, 2018 Naru2 yes they went bad at the same time Link to comment Share on other sites More sharing options...
Cougar Posted October 27, 2018 Share Posted October 27, 2018 Check for a loose fusible link connection, it is a fairly common issue. They are located in a small plastic box mounted on the coolant reservoir. Link to comment Share on other sites More sharing options...
Squidbilly503 Posted October 29, 2018 Author Share Posted October 29, 2018 On 10/18/2018 at 8:12 PM, DaveT said: I am not sure what you are saying here - You took the alternator out, and had places test it? Davet i removed the alternator from the car, took it to napa, car quest, autozone and an actual shop and had them test it. Link to comment Share on other sites More sharing options...
Squidbilly503 Posted October 29, 2018 Author Share Posted October 29, 2018 Cougar i replaced all the fusable links. But anything helps. Link to comment Share on other sites More sharing options...
DaveT Posted October 29, 2018 Share Posted October 29, 2018 I am interpreting that the places that tested it think it's working. Normal in the car should be around 13.8 V or into the 14s on the battery terminals with the engine running at a bit over Idle. Over 15 is bad also. At idle, the output can drop too low to charge. If it tests good I would be looking at the wiring to the 2 wires on the small connector on the alternator - everything involved with them. Link to comment Share on other sites More sharing options...
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