showing only 10 volts after battery remote

[rdharper02]

Need help. Remoted the battery, laid a 2G ground from the trunk and recently showing low voltage. Checked at the alternator and showed 10.2 volts. Replaced the alt and no luck. Anyone with any clue whats up? I am out of answers. Good Alt, good positive wiring, good ground. Dont know whats up.

 

[HISSIN50]

Did it ever function properly? 2 AWG is not optimal.

When does it show 10.2V? With the car off, while idling, at 2K RPM?

Is the alt receiving the signal to excite? Is the sense circuit still intact?

 

[rdharper02]

Lets see. 10.2 with the vehicle at idle. The two gauge runs from the battery to the engine compartment. 0g would have been better, but reality is that it still bolts through the chasis and has the length of cable. Grounds good. As far as the excite? fill me in.

 

[rdharper02]

Anyone else have any input?

 

[HISSIN50]

10.2 is severely severely discharged. I don't know how your car will even start.

On your alt, go to the regulator and check the terminal labeled I for voltage (2-12 V).
Check A for battery voltage.
Check S for 1/2 of battery voltage.

 

[rdharper02]

I dont know if it will start at that point. I have continued to remove the battery and replace it with one fresh off the charger. The benifit of finding a deal on an optima. I'm just as amazed as you are, but it idles at 10.2 without jumping up to the 13.8 range. I honestly think its the Hi-6r thats allowing it to run at all. The terminals, are they labled on the alternator itself, or is there a pictoral reference I am missing? (not with the car right now).

 

[HISSIN50]

I'm surprised it will start with that little potential. Below about 10 cranking volts generally will not turn a starter over.

Anyhoo, Do you have a 3 or a 2G? I'd assume the former. The regulators are wired the same. They are labeled A, S, I on the reg itself.

Going a step backwards, check the circuit protection on your power cable. If it's ok, then check your values at the regulator (checking the power cable first could save needlessly testing the reg wiring). I have the feeling that either the charge cable is open or the alternator is not exciting (I terminal). Here's the wiring pathway and colors on an aero fox (lower right-hand corner):

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

 

[rdharper02]

Its a 3g setup thats been in there for about a year. I got off work late today, but stopped by the bases hobby shop. One of the master techs ran me through the schematic and agrees its probably the exciter signal. Will have to wait until tomorrow to check it out. I am hoping that its corrosion in the connector or something simple, because Im not looking forward to tracking this past the harness.

The voltages give; do I need to have the vehicle running to check them?
Thanks again

 

[Kaseyinupt]

If the car has underdrive pulleys it will not charge well or at all at an idle but should around 1500 to 2000 rpm on the 88-93 from my experience

 

[rdharper02]

No underdrives. My old toy had underdrives and I had nothing but problems. Wasnt worth the few extra horses gained.

 

[HISSIN50]

Its a 3g setup thats been in there for about a year. I got off work late today, but stopped by the bases hobby shop. One of the master techs ran me through the schematic and agrees its probably the exciter signal. Will have to wait until tomorrow to check it out. I am hoping that its corrosion in the connector or something simple, because Im not looking forward to tracking this past the harness.

The voltages give; do I need to have the vehicle running to check them?
Thanks again

If your battery light proves-out (illuminates when you turn on the key), then the I circuit is probably not your issue. The regulator itself is what grounds (and ungrounds, once the car is running) that circuit.

If it is the excite circuit, we can get you functional with a 500 ohm resistor from Radio Shack (till you can solve a wiring issue).

You can test the A circuit anytime (it's battery power).
For I, i like to test it KOEO and KOER because the value changes as the regulator removes the ground. It really doesnt matter so long as you have some voltage in the circuit at all KOER times.

You need the car running to test the Stator (S) circuit voltage. (In order to test the loop for continuity, you need to have the key off and both plugs disconnected. I'd only test this if the stator circuit does not show half battery voltage KOER). This is the wire you spliced and looped during the 3G retrofit. If this is open, your alt won't charge.

 

[rdharper02]

OK tested S with nothing. "A" is running at .46v (could be potential from the meter). "I" is reading at 12.64 (battery voltage). So it looks like the "A" terminal is my problem. Went to check the ground on the front of the engine. The one that uses the same bracket as the wiring crossing under the engine. So I find the old Black and orange wire has made contact with the balancer and shorted. Is this link fused or am I going to have to track the wiring to see if it has lost connection somwhere?

 

[HISSIN50]

Yep, that's the old charge cable. I hope you are not reusing it as a charge cable with your 3G. The good way to retrofit the wiring is to disconnect and insulate the rectifier plug (that houses the two charge wires and one leg of the stator wire) on the alternator side. On the solenoid side, you leave it connected so the A (sense) portion of the circuit still functions. If your OEM charge wire shorted, it probably burned the charge cable's fusible link (14 AWG) or the sense circuit's 18 gauge link. Which one(s) burned will depend partially upon if you reused the stock charge wires on the 3G charge stud.

You can either find the issue in the wiring and repair it or you could create a new wire. To keep the sense circuit functional, you would cut the OEM sense (A) wire at the reg plug and then solder on a new wire, which will run to the solenoid's battery lug. You could use an 18 AWG link on this new wire (as was OEM) or you could probably install a 20 amp fuse, which is how that portion of the circuit is protected on a 94-95 Mustang. See the 94-95 schematic:

http://www.veryuseful.com/mustang/tech/engine/images/Mustang-94-95-Alt.gif

The point of protecting that circuit is that if your charge-cable's fuse blows, you don't want the sense wire trying to carry the alternator's load to the solenoid.

For super quick diagnostics, you could cut the sense wire at the reg and run a little fused (20 or 10 amp) jumper wire to the 3G's charge lug. This defeats the point of remote sensing (which accomodates voltage drop in the wiring) but it does make the circuit functional. Just do this for diagnostics.

 

[rdharper02]

Didnt use the factory wiring. I have it cut and terminated, but noticed it connects back towards the same path as "A". I hate to do it, but It looks like I will probably run a new wire. So where is the fusable link at on this wire? Just curious, because I think I will end up going with the 94 and up wiring scheme. Thanks again

 

[HISSIN50]

IIRC the link is just off the solenoid.

I'd also use a fuse and new wire if in your position.

 

[rdharper02]

Still havent had a chance to get to it, but plan to drop a test wire from the solenoid to "A". I let you know how it goes

 

[rdharper02]

Dropped the test line. Definitely the problem. I didnt have time to do the right thing a nd track the problem down. I removed some of the factory wiring and dropped a 14g line (w/fuse) from the "A" connection. I laid it along witj the 3g wiring, so It looks factory. Did give me a chance to remove the factory AC condensor, so all is good. Thanks HISS. Its guys like you and J that have helped me keep my motivation on a vehicle I see five months out of the year for the last five years.

 

[HISSIN50]

Glad to hear you got it circumvented.

Thank you for your service!