Ill try to keep this brief. Alternator went bad on my sons 86 GT. I replaced the 86 style alternator with the better 88 style. I bought the adapter plug for it and now after a week or so of driving the volt light is on, the battery is not maintaining voltage, at least according to the gauge, and I am now stumped. I do not know what the issue is. Before I go back and buy an 86 alternator, what could the issue be? Thanks.
With a volt meter bridging the pos and neg terminals on the battery, what voltage do you measure when the engine is off. And what is the voltage when the engine is running?
With a volt meter bridging the pos and neg terminals on the battery, what voltage do you measure when the engine is off. And what is the voltage when the engine is running?
Well I lied. I squeezed in a few minutes at lunch and took a reading. 12 volts off. Dropping when running. 11, 10, 9...and then i turned off the car. Assuming I used the volt meter correctly. Its not my thing.
It sounds like the alternator has failed. Take it into a parts store and have it tested to confirm. Also, make sure you have the battery tested at the same time.
Originally posted by NW-Fiero: Does this mean that the volt light was not on after the conversion.... & the battery was charging... OR ...that the new alternator was never working??
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Well thats the million dollar question. The battery is new, bought the same time as the alternator. It appeared everything was good for about a week. Dash guage was saying around 13 volts and no light and then this morning on the way to work the guage was reading around 8 or 9 volts and the light was flickering off and on. By the time i went home at lunch, the light was on solid. I took the readings then and its apparent it is not charging, but why? Unfortunately, it looks like I have to take the alternator off and bench test it. I guess its possible I got a defective one off the shelf. If it test out ok i guess it could be the adapter, but I dont know how to test that. It also could be an issue somewhere else, but thats a guess and i dont know where to begin.
It sounds like the alternator has failed. Take it into a parts store and have it tested to confirm. Also, make sure you have the battery tested at the same time.
Battery is new. It will royally piss me off if I got a defective alternator off the shelf.
I replaced the 86 style alternator with the better 88 style. I bought the adapter plug for it and now after a week or so of driving the volt light is on, the battery is not maintaining voltage...
I haven't looked at one, but I would imagine the adapter plug is a rather simple device. Anything on it that can fail? Still plugged in securely at both ends?
[This message has been edited by Patrick (edited 10-13-2015).]
I haven't looked at one, but I would imagine the adapter plug is a rather simple device. Anything on it that can fail? Still plugged in securely at both ends?
I'm thinking the same thing. Its just wires with the appropriate plugs at each end. Each end is still plugged in. I don't see much on it that could fail, but just thinking out loud, I guess one of the plugs could not be seated properly or maybe a wire is not soldered in correctly. I just dont know at this point.
Jim
[This message has been edited by jimbolaya (edited 10-13-2015).]
Its just wires with the appropriate plugs at each end. I don't see much on it that could fail, but just thinking out loud, I guess one of the plugs could not be seated properly or maybe a wire is not soldered in correctly.
Before pulling the alternator, I'd remove the adapter and check continuity on all the wires/plugs. You might get lucky!
[This message has been edited by Patrick (edited 10-13-2015).]
Hi Jim, sorry to hear you are having all the problems.
I think I remember from your other thread that you have the adapter "with light" which has a resister in it. That is the ones I've always used many times with no issues.
You might try this. unwrap the wiring harness on the adapter harness, remove the resister that is connected in one of the wires, and then connect the ends of the wires where the resister was together.
hook everything back up, retest and see if the light and charging issues are corrected. It may be that the adapter has a bad resister in it, or something else in the car is causing too much resistance in the cars wiring harness to get the alternator to trigger and charge.
hope this helps!
------------------ "Because in a split second, It's gone" Ayrton Senna
Hi Jim, sorry to hear you are having all the problems.
I think I remember from your other thread that you have the adapter "with light" which has a resister in it. That is the ones I've always used many times with no issues.
You might try this. unwrap the wiring harness on the adapter harness, remove the resister that is connected in one of the wires, and then connect the ends of the wires where the resister was together.
hook everything back up, retest and see if the light and charging issues are corrected. It may be that the adapter has a bad resister in it, or something else in the car is causing too much resistance in the cars wiring harness to get the alternator to trigger and charge.
hope this helps!
Good memory, and good tip. Probably will not be able to get to it till the weekend though.
Are these the same symptoms the car had that originally prompted the replacement? Maybe you have an upstream problem rather than an alternator problem. Does the S wire have a good connection to a battery + source? Do you have a good 12v on the "L" wire with the ignition on? That said, a CS130 should eventually self-excite so the L wire probably isn't important, but still worth a check. I don't think the Fiero uses the P or F wires, but don't quote me on that.
My third lifetime warranty alternator was the charm. I have bought so many defective auto parts in my years. I am currently attempting to find a thermostat that I do not have to drill for my Ford F150? Quality is not an issue in China.
FWIW, I've found the parts-store CS plug is usually a brittle piece of junk. I went through about three of them before giving up and cutting one from a car in the junkyard. The storebought ones would either not snap in all the way, or else the clip would crack off and the plug would become loose after awhile. The OEM one from the junkyard was considerably more durable. No issues.
So I had a friend come over and I have the wrong plug. The plug only has two wires and the red one should split off to two pins. The S and the F. The third pin "L" is for the remaining wire. So its not charging properly because of the adapter plug. I need to buy the right one. Only problem is, the ones I am being shown online all look like the one I bought. I need to confirm somehow I am purchasing the correct one. Even the one Ponnari recommended in a previous thread appears to be the same as the one I bought. Can anyone confirm or link me to the exact one I need?
I don't mind telling you I do not understand any of this. I just spent some time in Orgre's cave and I'm more confused now than ever before. I have the 88 alternator in the 86 car, I just need the right plug adapter, and plug it in, and in theory it should work. I'm trying my hardest to understand this, but I just can't grasp it. I think we are just going to go back and buy an 86 alternator and be done with it.
Jim
[This message has been edited by jimbolaya (edited 10-18-2015).]
You would think so but its not. I have what is supposed to be an adapter plug, and it matches the wiring shown in the instructions you post from Ogre's cave. However, the wiring diagram for an 88 also shows a wire from the F/I slot coming from the alternator. Is it supposed to be 3 wires or 2? I'm lost.
Upon further review perhaps the adapter plug is wired correctly and either the brand new alternator is bad or I have a wiring issue. I dont want to take the alternator out again, but I have no idea how to trace down a wiring issue, so ill take the alternator out and have it bench tested. If its good, then im pretty much screwed!
I dont want to take the alternator out again, but I have no idea how to trace down a wiring issue, so ill take the alternator out and have it bench tested.
Why take it out for that?
quote
Originally posted by Patrick:
You should also check the voltage directly off the alternator.
Because I have no idea how to do that and eliminate the adapter as part of the equation.
As far as I know, you can get a voltage reading from the terminal on the alternator that the one wire is attached to with a nut. However, I'm no electrical wizard, so get confirmation from someone else here before you try it.
[EDIT] Take the reading from where it says BAT (which I have to assume is short for battery).
[This message has been edited by Patrick (edited 10-19-2015).]
The 88 alternator is wired as follows.... 'S' - red wire, battery junction block, fused 10A or fuse link 'E' 'F' - brn/wht wire, Fan 'E' fuse, 20A 'L' - brn wire, gage fuse, 10A 'BAT' - heavy red wire, battery junction block, fuse link 'E'
If you have 12V, key off, on 'S', and 'BAT' and 12V, key on at 'F' and 'L', the alternator should work. The charge light circuit is on 'L'.
If the alternator doesn't charge with the above conditions met, the alternator is defective.
Check the battery too, I have had some that discharge on their own on a bench, and I have had one that only took 7 volts in and would charge no higher.
Loose connections. I have an '85 GT (with air) that seems to have intermittent alternator problems. I bought the '88 alternator and connector but haven't installed them yet because I want to make sure it's the alternator and not something else. It seems that what often happens in this situation is people replace the alternator and battery and it turns out to be something else. Yesterday I was trying to track down what that something else might be. Didn't find anything, but lo and behold, the charging system worked much better than before I went poking around the fuse box. There is another recent thread where it turned out the battery junction had been left loose. All I did was drop the fuse box and pull the gauges, fuel, and radio fuses to check the circuit with a tester thing I got off Amazon. I also dislodged and replaced (at least twice) the neutral safety switch bypass.
I have this car on an analyzer/charger with the battery disconnected. Last time I drove it my external Radioshack voltmeter showed it overcharging as soon as it started. When I returned from a few miles driving the charger reported the battery was down to 57%. Yesterday after my tests with the battery and charger connected and still fully charged, it did not overcharge. When I returned from the exact same trip the charger reported the battery was at 87%.
If you retrace your steps and make sure everything is tight and in place you might find it working again.
As stated above, the brown wire with the charge light is fed by the GAGE fuse.
I couldnt take it anymore so i went out in the dark, with a flashlight, and checked the fuse. It was fine, but Joe your 88 wiring is what has me confused. I have seen that before. My car is an 86 so it does not have the F brown/white wire. So how is the adapter plug, and 88 alternator, supposed to account for missing wire? The adapter plug is just 2 wires with the appropriate plastic connectors on each end. It seems to me the adapter should connect the two wires from the 86 wiring to the 3 points that it should be connecting to on the 88 alternator. Like I said before the electrical stuff always confuses me, but it seems logical that if the 88 has 3 wires and the 86 has just 2, somehow the adapter should split to 3 points. Sorry if this makes no sense.
Jim
[This message has been edited by jimbolaya (edited 10-21-2015).]
That would be incorrect. Each terminal on the CS130 alternator has its own function. Not all functions are needed to run the alternator, but when present and used they will influence the alternator's behavior. Connecting three alternator-side terminals to two chassis-side terminals would have at best no effect and at worst a bad effect. The four terminals on the CS130 are:
L = charging Lamp P = Phase connection, alternator speed F = Field monitor, amp monitor S = Sense, voltage monitor
The only terminal you *need* connected is S. Sense is how the alternator knows what its output is. Without it, it will do nothing. With only S connected, you are relying on the alternator to self-excited (start charging), which will only happen after it has some speed. S can be connected "deep" in the wiring harness to help account for voltage loss or can be connected directly to the BATT terminal to measure there.
You generally want L connected. L is connected via a Lamp or resistor (or both) to a switched ignition source. When 12v is present on L, the alternator will begin charging. By using L, you tell the alternator to start charging now as opposed to waiting for it to self-excite. Some CS130s will have an I instead of L. They are more or less interchangeable in terms of function, but behave differently. You will find L or I, never both.
P and F are application specific and typically used for operational or diagnostic purposes in combination with ECM features. You won't ever use these on older cars. They are not necessary or operation of the alternator.
By way of example, on my 1967 Fleetwood, my CS130 alternator uses only BATT, S, and L. S is connected to BATT and then connected to the vehicle battery. One wire. L is connected to the brown wire that goes first to the GEN light, and then to the ignition switch. Two wires. That's it. That's all that is needed.
[This message has been edited by thesameguy (edited 10-21-2015).]
Sorry to confuse the issue with the F connection. I should have been more clear and written "If you have 12V, key off, on 'S', and 'BAT' and 12V, key on at 'L', the alternator should work."
Thanks that clears up a lot of my confusion on that part. I really think I have a bad alternator even though its new. Its been hard to test because its getting dark early and I haven't been getting home in time to check it. I do not have a garage.
Jim
[This message has been edited by jimbolaya (edited 10-22-2015).]
I am absolutely embarrassed to disclose this, but I must for posterity and the hopes that others will not be as stupid as I. I went to go take some readings on the alternator this morning and when I pulled back the rubber boot covering the post of the alternator, I discovered the nut holding the wire onto the alternator had backed off. The wire was not making a solid connection and that explains why it was charhing for two weeks and then suddenly stopped. 😮 Would a little dab of thread lock be ok to prevent it from backing off again? Thanks for everyone's patience.
Jim
[This message has been edited by jimbolaya (edited 10-24-2015).]
I have bought so many defective auto parts in my years. I am currently attempting to find a thermostat that I do not have to drill for my Ford F150? 
Quality is not an issue in China.
