2G Constant Electrical Surge

[Batterykiller719]

I'm fed up and on my last nerve with my '95 GSX. It has an electrical surge that makes ALL my lights flash/strobe; head lights, interior lights and numerous other circuits. The voltage fluctuates from 12.9 to 15.2 while its running. It started with only when the RPMs would rise over 3k and now it's all the time. So I replaced the alternator, ckecked and cleaned all grounds for engine and chassis, changed pos and neg battery cables. Ended up with the same result. I disconnected the fusable links from the alternator to the fuse box in the engine bay and the probem went away? Is the new alternator defective?

 

[luv2rallye]

Probably. Reman alts from auto stores are 90% of the time junk. With warranty take it back and try another. Believe me they WON'T be surprised you're back with a defective new alt!

 

[waltah]

The new alternator could be defective too but that's not where I'd start.

Alternators have traditionally had four connections: Ground, Output which supplies power to the battery, a Sensing line that informs the alternator of the actual voltage at the battery (this takes care of loss in the wiring), and Signalling ,a connection that is used to operate the alternator idiot light. The alternators in the 2g cars (probably lots of others but I don't know more recent ones) add two more connections.

One -- the Fr terminal -- tells the ECU how hard the alternator is working. This lets the ECU adjust the engine idle speed to compensate for the alternator load. This is equivalent to the signals from the air conditioning compressor and the power steering pump: Knowing that load is going up or down lets the ECU (by control of the ISC valve in the throttle body) prevent changes of engine speed rather than having to notice them and react.

And another -- the G terminal -- lets the ECU take control of the alternator to limit its output. These cars have lots of electrical loads and a big alternator; it's possible for these alternators to self-destruct under certain conditions. For example when you install a new alternator and the battery's new and fully discharged it can draw enough current to kill the alternator. (I've had this happen so I know it's real -- it's why alternator installation instructions often tell you 'charge the battery before starting the car.') The 2g Eclipse ECU manages the alternator output so it doesn't work itself to death and is able to adjust the output all the way from nothing (12.3 volts so no current flows to the battery) up to full output for a normal system (14.4 volts).

I'll bet the trouble is connected with that G terminal: Certainly a bad connection there would cause flashing of the lights, a bad ECU could also do so. I'd check the wiring from G to the ECU. You could also put a voltmeter on that terminal: I think it's not supposed to go up and down fast, but only slowly in response to what it thinks the alternator can handle. The electrical volume of the shop manual may have more info on that.

Edit: Is the new alternator mounting clean and tight? I'll bet that a poor ground there could cause much trouble via that G control line. Check the voltage from the alternator frame to the battery ground terminal -- should not be more than a fraction of a volt.

I knew when I saw those new connections (reading the manual when I got the car) that they were going to be a way to have new interesting problems. And here they are!

 

[Batterykiller719]

The new alternator could be defective too but that's not where I'd start.

Alternators have traditionally had four connections: Ground, Output which supplies power to the battery, a Sensing line that informs the alternator of the actual voltage at the battery (this takes care of loss in the wiring), and Signalling ,a connection that is used to operate the alternator idiot light. The alternators in the 2g cars (probably lots of others but I don't know more recent ones) add two more connections.

One -- the Fr terminal -- tells the ECU how hard the alternator is working. This lets the ECU adjust the engine idle speed to compensate for the alternator load. This is equivalent to the signals from the air conditioning compressor and the power steering pump: Knowing that load is going up or down lets the ECU (by control of the ISC valve in the throttle body) prevent changes of engine speed rather than having to notice them and react.

And another -- the G terminal -- lets the ECU take control of the alternator to limit its output. These cars have lots of electrical loads and a big alternator; it's possible for these alternators to self-destruct under certain conditions. For example when you install a new alternator and the battery's new and fully discharged it can draw enough current to kill the alternator. (I've had this happen so I know it's real -- it's why alternator installation instructions often tell you 'charge the battery before starting the car.') The 2g Eclipse ECU manages the alternator output so it doesn't work itself to death and is able to adjust the output all the way from nothing (12.3 volts so no current flows to the battery) up to full output for a normal system (14.4 volts).

I'll bet the trouble is connected with that G terminal: Certainly a bad connection there would cause flashing of the lights, a bad ECU could also do so. I'd check the wiring from G to the ECU. You could also put a voltmeter on that terminal: I think it's not supposed to go up and down fast, but only slowly in response to what it thinks the alternator can handle. The electrical volume of the shop manual may have more info on that.

Edit: Is the new alternator mounting clean and tight? I'll bet that a poor ground there could cause much trouble via that G control line. Check the voltage from the alternator frame to the battery ground terminal -- should not be more than a fraction of a volt.

I knew when I saw those new connections (reading the manual when I got the car) that they were going to be a way to have new interesting problems. And here they are!

I did not clean the alternator bracket, but I can unbolt it and wire wheel it. Also, I've read that adding a ground strap to the case of the alternator can help too?

 

[Batterykiller719]

Probably. Reman alts from auto stores are 90% of the time junk. With warranty take it back and try another. Believe me they WON'T be surprised you're back with a defective new alt!

Thanks luv2rallye, I thought that might have been the issue cuz the problem was solved for about a day and then came back.